Glossary

A

AAR - Association of American Railroads; see organizations, Association of American Railroads.

AC - Alternating Current

ACCESS - Permission, liberty, or ability to enter, approach, or make use of.

Limited (controlled access) - in transportation, to have entry and exit limited to pre-determined points, as with rail rapid transit or freeways.

ACV - Air Cushion Vehicle - (See VEHICLE, Air cushion).

AFC - Automatic Fare Collection - (See FARE COLLECTION SYSTEM, Automatic).

AGT - Automated Guideway Transit

ALRV - Articulated Light Rail Vehicle

ATC SYSTEM - Automatic Train Control system

ATD - Automatic Train Dispatch

ATO - Automatic Train Operation

ATP - Automatic Train Protection.

ATS - Automatic Train Supervision

ABANDONMENT - 1. In public transportation operations, a procedure whereby a carrier ceases operations on all or part of its lines and routes on permission from the appropriate regulatory authorities. 2. With rights-of-way, the relinquishment of the public interest in right-of-way or activity thereon with no intention to reclaim it or use it again for transportation purposes; also known as vacation.

ABSOLUTE BLOCK - A block which no train is permitted to enter while it is occupied by another train.

ABSOLUTE STOP - A signal indication which requires a train to stop and not proceed.

ACCELERATION - Increase in velocity per unit time; in transit, usually measured in feet per second squared (meters per second squared) or, in the United States, sometimes in miles per hour per second.

ACCELERATION RATE - Time rate of change of speed of a vehicle.

ACCESSIBILITY - 1. A measure of the ability or ease of all people to travel among various origins and destinations. 2. In transportation modeling and planning, the sum of the travel times from one zone to all other zones in a region, weighted by the relative attractiveness of the destination zones involved. 3. In traffic assignment, a measure of the relative access of an area or zone to population, employment opportunities, community services, and utilities. 4. The extent to which facilities are free of barriers and usable by mobile handicapped people, including wheelchair users.

Handicapped (full accessibility) - the extent to which facilities are free of barriers and usable by mobile handicapped people, including wheelchair users.

ACCESSIBLE TRANSPORTATION FACILITIES - Transportation facilities that are barrier-free, allowing their use by all travelers, including the mobile physically handicapped, elderly, and transportation disadvantaged.

ACCIDENT - An unforeseen event or occurrence which results in injury or property damage.

AERIAL STRUCTURE - In transportation, any structure other than a culvert that carries a roadway or track or other guideway above an earth or water surface; see also GUIDEWAY, Elevated.

AERIAL TRAMWAY - In passenger transportation, a mode consisting of cabins suspended from a stationary cable and towed by a moving, usually closed-loop, cable; used to overcome steep gradients, deep valleys, or bodies of water.

AIR CUSHION SYSTEM - (See TRANSPORTATION SYSTEM, Air cushion).

AIR CUSHION VEHICLE - (See VEHICLE, Air cushion).

AIR POLLUTION - The presence of unwanted material in the air in sufficient amount and under such circumstances as to interfere significantly with human comfort, health, or welfare, or with full use and enjoyment of property.

ALARM CONDITION - Any abnormal condition which requires the attention or intervention of responsible personnel or an individual monitoring the transit system operation.

ALIGNMENT - In transportation, the horizontal and vertical ground plan of a roadway, railroad, transit route, or other facility as it would appear in plan and profile. The alignment is usually described on the plans by the use of technical data, such as grades, coordinates, bearings, and horizontal and vertical curves.

ALTERNATIVES ANALYSIS - A detailed study and assessment of the various options available for the purpose of selecting one for implementation. Ideally, all feasible alternatives will be investigated. An alternatives analysis is required if funds are sought from the Urban Mass Transportation Administration for capital-intensive major transportation projects.

AMBIENT AIR QUALITY - A physical and chemical measure of the concentration of various chemicals in the outside air, usually determined over a specific time period, for example, S minutes, 1 hour, or 1 day.

APPLICATION, BRAKE - The application of brakes to achieve the desired rate of either service deceleration or emergency deceleration.

APPROACH INDICATOR- An indicator used to indicate the approach of a train.

APPROACH LOCKING - Electric locking effective while a train is approaching a signal displaying an aspect to proceed, which prevents the movement of any interlocked or electrically locked switch, movable point frog, or derail in the route governed by the signal. Control is over a predetermined distance and incorporates a predetermined time release. (See also INTERLOCKING and DETECTOR, Track circuit)

APPROACH SIGNAL - A fixed signal used in connection with one or more signals to govern the approach thereto.

AREA -

Multiple-use - a transportation right-of-way used for other purposes in addition to transportation, for example, as a park; see also JOINT-USE CORRIDOR.

AREA OCCUPANCY - In station and other facility design and in pedestrian movement, the area provided per person.

ARMATURE - The part, usually revolving, of an electric motor or generator that includes the main current-carrying winding and in which the electromotive force is induced.

ARTICULATED BUS OR ARTICULATED TROLLEYBUS -An extra-long, high-capacity bus or trolleybus that has the rear body section or sections flexibly but permanently connected to the forward section. The arrangement allows the vehicle to bend in curves and yet have no interior barrier to movement between the two parts. Typically, an articulated bus is 5 S 60 ft (16-18 m) long and has a passenger seating capacity of 60 to 80.

ARTICULATED RAIL VEHICLE (ARTICULATED CAR) - An extra-long rail vehicle with two or more bodies connected by joint mechanisms that allow bending in curves yet provide a continuous interior. Typically, the vehicle is 56-1 00 ft (1 7-33 m) long. It is very common on light rail transit systems but is also found on several rail rapid transit systems. 2. Rapid transit cars with separate bodies that share a common center truck. 3. Rapid transit cars in consist with two trucks on each car and bodies joined so that passengers can walk between the cars.

ASPECT, FALSE CLEAR -The aspect of a signal that conveys an indication less restrictive than intended.

ASPECT, FALSE RESTRICTIVE - The aspect of a signal that conveys an indication more restrictive than intended.

ASPECT, SIGNAL - The display or presentation of a wayside signal that provides an indication viewed from the direction of an approaching train- the appearance of a cab signal conveying an indication as viewed by an operator in the cab.

ASPECT -The display or presentation of a wayside signal that provides an indication viewed from the direction of an approaching train; the appearance of a cab signal conveying an indication as viewed by an operator in the cab.

ASSIGNMENT, TRAFFIC OR TRIP - (See TRIP ASSIGNMENT.)

ASYMMETRICAL MONORAIL - (See TRANSIT SYSTEM, Monorail.)

ATTENDANT, TRAIN - A transit employee on board a train in service whose principal duties are to oversee safety, provide required security, and to assist in emergency operations.

ATTRITION ARRANGEMENT - In labor, the policy of relying on voluntary resignations, deaths, and retirements instead of layoffs to reduce the labor force of a company or organization.

AUDIO FREQUENCY TRACK CIRCUIT - Track circuit energized by electrical

current in the audio frequency range.

AUDIT CHECKLIST - A list of items derived from the System Safety Program Plan that will be examined in detail during an audit. Each item on the checklist will be rated as either being in conformance with, or in exception to, the System Safety Program Plan.

AUDIT - Formal or official examination to verify an item or activity against an identified standard.

AUTOMATED GUIDEWAY TRANSIT (AGT) SYSTEM - A fixed guideway transit system designed to operate without an operator onboard the vehicle.

AUTOMATIC - A term applied to a system, subsystem, or device which has the inherent capability to function without direct manual participation.

AUTOMATIC AIR BRAKE - (See BRAKE, Automatic air.)

AUTOMATIC BLOCK SIGNAL SYSTEM - 1. A block signal system wherein the use of each block is governed by an automatic block signal, by the cab signal indicator of an automatic speed control system, or by both. 2. A series of consecutive blocks governed by block signals, cab signals, or both, actuated by train movement or by certain conditions affecting the use of a block.

AUTOMATIC CAB SIGNALING (See SYSTEM, Automatic Cab Signal) - An automatic block signal system in which cab signals are provided.

AUTOMATIC CAR IDENTIFICATION (ACI) - A system providing positive recognition and the transmission of the individual number of a train automatically at specific line locations.

AUTOMATIC INTERLOCKING (See INTERLOCKING, Automatic) - An interlocking controlled by circuit logic so that movements succeed each other in proper sequence without need for manual control.

AUTOMATIC PROGRESSION - 1. A labor policy by which pay rate ranges or rates of pay of workers in jobs with established rate ranges are increased automatically at fixed intervals to the maximum rate for the classification. 2. Automatic movement from a trainee pay to the pay rate of a job classification or to the minimum level of a rate range. 3. A method by which workers move according to an agreed-on schedule from one pay scale to another automatically in a specified period of time.

AUTOMATIC SAFETY SWITCH - A switch, identified by a yellow switch stand, through which trains and engines may make trailing movements without previously aligning it by hand.

AUTOMATIC SPEED CONTROL SYSTEM - A system so arranged that its operation will automatically result in the following: A full service application of the train brakes if, while operating under a speed restriction, the speed of the train exceeds the predetermined rate. The application will continue until the train is either brought to a stop, or under the control of the engineer, its speed is reduced to the predetermined rate.

AUTOMATIC TRAIN CONTROL (ATC System) - 1. A system which enforces speed restrictions and prevents exceeding speed restrictions by automatic brake application; may additionally encompass automatic train operation, automatic train protection, and automatic train supervision. 2. The ATC System consists of three control subsystems and a computerized Central Control Facility. The three control subsystems are Automatic Train Operation (ATO), Automatic Train Protection (ATP), and Automatic Train Supervision (ATS). Each performs its own particular functions independently of the other two to a certain extent. The operations of the three subsystems are coordinated through the computer at Operations Control Center to achieve an integrated system. 3. A system for automatically controlling train movement, enforcing train safety, and directing train operations by computers; see also AUTOMATIC TRAIN OPERATION, AUTOMATIC TRAIN PROTECTION, and AUTOMATIC TRAIN SUPERVISION. 4. A trackside system working in conjunction with equipment installed on the train, arranged so that its operation will automatically result in the application of the brakes to stop or control a train's speed at designated restrictions, should the operator not respond. The system usually works in conjunction with cab signals.

AUTOMATIC TRAIN DISPATCHER (See DISPATCHER, Automatic Train) - A programmable device whose function it is to dispatch trains on a predetermined schedule.

AUTOMATIC TRAIN OPERATION (ATO) - l. That subsystem within the automatic train control system which performs any or all of the functions of speed regulation, programmed stopping, door control, performance level regulation, and other functions normally assigned to the train operator. 2. That subsystem within the ATC System which performs functions normally performed by the operator. These functions are regulation of acceleration rate, speed, rate of deceleration, programmed stopping, and door control in conjunction with ATP and the Train-to-Wayside Communication System.

AUTOMATIC TRAIN PROTECTION (ATP) [RAIL] - That subsystem within the ATC System which enforces safe operation of the system. It imposes speed limits both to maintain train separation and to operate trains in accordance with civil speed restrictions. At inter-lockings, a TP ensures that train movement is permitted only when a route is available through the interlocking, and the switches are safely locked in position. In all cases where two or more trains request the use of a single segment of track or interlocking, the ATP prevents occupancy by more than one train.

AUTOMATIC TRAIN STOP (See SYSTEM, AUTOMATIC TRAIN STOP) - A system in which the train is brought to a stop through automatic brake application if imposed restrictions are ignored.

AUTOMATIC TRAIN SUPERVISION (ATS) -That subsystem within the automatic train control system which monitors the system status and provides the appropriate controls to direct the operation of trains in order to maintain intended traffic patterns and minimize the effect of train delays on the operating schedule.

AUTOMATIC TRAIN SUPERVISION (ATS) [RAIL] - The ATS subsystem controls and supervises the routing and scheduling of the trains. ATS also supervises and controls the transit system mechanical support and electrical power facilities.

AUTOMATIC TRAIN STOP SYSTEM (ATS) - A trackside system that works in conjunction with equipment installed on the electric rail car or locomotive to apply the brakes at designated restrictions or on a dispatcher's signal, should the operator not respond properly.

AUTOMATIC TRAIN SUPERVISION (ATS) - The subsystem within automatic train control that monitors trains, adjusts the performance of individual trains to maintain schedules, and provides data for adjusting service to minimize the inconveniences otherwise caused by irregularities.

AUTOMATIC VEHICLE LOCATION SYSTEM (AVL) - A system that senses, at intervals, the location of vehicles carrying special electronic equipment that communicates a signal back to a central control facility. AVLs are used for detecting irregularity in service and are often combined with a computer-aided dispatch system.

AUTOMATIC VEHICLE MONITORING SYSTEM (AVM) - A system in which electronic equipment on a vehicle sends signals back to a central control facility, locating the vehicle and providing other information about its operations or about its mechanical condition.

AVAILABILITY - The probability that a system or system element will be operational when required. Mathematically, the ratio of the mean time between failure to the sum of mean time between failure plus mean down time.

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B

BACKUP - An alternate means of accomplishing a function using software, hardware, circuits or operational procedures separate from those used for the primary method.

BACKUP SYSTEM - A redundant system that performs the principal functions of the primary system with minimum deviation from the performance of the primary system.

BAD ORDER - 1. A notice that a transit unit or locomotive needs repair. 2. A defect in a device or a transit unit or locomotive needing repair.

BALLAST - Material placed on a track bed to hold the track in line and elevation and to distribute its load. Suitable material consists of hard particles (e.g., crushed rock, slag, gravel) that are stable, easily tamped, permeable, and resistant to plant growth.

BALLAST IMPEDANCE (See IMPEDANCE, BALLAST) - The impedance shunting a track circuit due to the condition of the ballast.

BALLAST LEAKAGE - The leakage of current from one rail of a track circuit to the other through the ballast, ties, etc.

BASE PERIOD (off-peak period) - In transit, the time of day during which vehicle requirements and schedules are not influenced by peak-period passenger volume demands (e.g., between morning and afternoon peak periods). At this time, transit riding is fairly constant and usually low to moderate in volume when compared with peak-period travel. (See also OFF PEAK.)

BASE-PERIOD FLEET - In transit, the number of transit units (vehicles or trains) required to maintain base-period schedules.

BASIC OPERATING UNIT - In rail rapid transit, the smallest number of rapid transit vehicles that can operate independently in revenue service, usually one to three (exceptionally more) cars. BERTH, TRAIN -The space designated for a train of given length to occupy when it is stopped at a station platform, in a terminal, on a transfer track, or at some other designated place.

BLOCK - 1. A section of track or guideway of defined limits on which the movement of trains is governed by block signals, cab signals, or both; also known as a signal block. 2. A section of track of defined length, the occupancy of which is regulated by fixed signal(s), telephone or radio orders, or timetables-, also known as a block section. 3. The daily operating schedule of a transit unit (vehicle or train) between pull-out and pull-in, including scheduled and deadhead service. A block may consist of a number of runs. 4. A length of track of defined limits, the use of which by trains is governed by block signals, cab signals, or both. 5. A length of track of defined limits, the use of which by trains and engines is governed by block signals, block-limit signals, automatic speed control, or any combination thereof. 6. A length of track of defined limits, the use of which is governed by block signals, cab signals, or both, or other set procedures.

Absolute - A section of track between two specific locations into which no train is permitted to enter while that section is occupied by another train. This absolute block is established and governed by the Operations Control Center when necessary, due to a carborne malfunction (e.g., ATP or Braking) or ATC failure.

Absolute permissive - a signal system for a single track or guideway that prevents simultaneous opposing train movements between sidings but permits following movements at a safe distance.

BLOCK, AUTOMATIC (See AUTOMATIC BLOCK SIGNAL SYSTEM) - A series of consecutive blocks governed by block signals, cab signals, or both, actuated by train movement or by certain conditions affecting the use of a block.

BLOCK INDICATOR - A device, generally located near a turnout switch, that is used to indicate the presence of a train in the block or blocks leading to that switch.

BLOCK-LIMIT SIGNAL - A fixed signal indicating the limit of a block, the use of

which by trains is prescribed by manual block signal system rules.

BLOCK-LIMIT STATION - A place at which a block-limit signal is displayed.

BLOCK, MANUAL (See SYSTEM, MANUAL BLOCK) - A block signal system operated manually, usually based on information communicated by telegraph or telephone.

BLOCK MILEAGE (block kilometers) - The distance traveled daily during the operating schedule of a transit unit (vehicle or train) from pull-out to pull-in, including scheduled and deadhead service. BLOCK NUMBER - A letter/number combination assigned to a segment of a bus

schedule and displayed in the right front window of a bus.

BLOCK, PERMISSIVE - A block which permits a train to enter while it is occupied by another train.

BLOCK SIGNAL CONTROL - See control system, block signal; and control system, automatic block signal.

BLOCK SIGNAL - A fixed signal, or hand signal in the absence of a fixed signal, at the entrance of a block to govern trains and engines in entering and using that block.

BLOCK SIGNAL SYSTEM (See SYSTEM, BLOCK SIGNAL) - A method of governing the movement of trains into or within one or more blocks by block signals or cab signals.

BLOCK SIGNAL (See SIGNAL, BLOCK) - A fixed signal at the entrance to a block to govern trains entering that block.

BLOCK STATION - A place at which manual block signals are displayed.

BOARDING - To embark on a vehicle.

BODY-ON-CHASSIS - A vehicle that has a body fastened to a chassis usually built for trucks, as is typical in school bus construction; distinguished from integral construction, in which the frame and body are built as one unit.

BOND, IMPEDANCE - An iron core coil of low resistance and relatively high reactance, used to provide a continuous path for the return propulsion current around insulated joints and to confine the alternating current signaling energy to its own track circuit.

BOND, INDUCTIVE COUPLED IMPEDANCE - A device of low resistance and high reactance, used with jointless audio frequency track circuits to couple inductively and confine the signaling energy to its own track circuit and equalize the return propulsion current between rails without impeding its flow.

BOND, PROPULSION - A conductor of low resistance providing a path for the return propulsion current at non-insulated joints.

BOND, SIGNAL -A conductor of low resistance providing a path for track circuit

current across bolted rail joints.

BONDING (RAIL) - The connection of rails or frogs to provide a continuous path for signal or propulsion current by use of bonds.

BOOK OF RULES - A set of codified regulations and procedures by which operating personnel are governed.

BRAKE -

Air - a break in which the mechanism is actuated by manipulation of air pressure.

Automatic air - a brake in which air is stored above atmospheric pressure so that a reduction in pressure in the brake line (intentional or by some failure) causes a valve in each rail car to use air from an auxiliary reservoir to build up pressure in the brake cylinder, thus applying the brakes.

Continuous (trainlined brake) - a system of brakes inter-connected among rail cars so that the brakes on all cars in the train can be operated simultaneously from the locomotive or from any car in a multiple-unit train.

Disc - a brake used primarily on rail passenger cars that uses brake shoes clamped by calipers against flat steel discs.

Dynamic (electric brake, electrodynamic brake, motor brake) - a system of electrical braking in which the traction motors, used as generators, retard the vehicle by converting its kinetic energy into electrical energy. This energy is absorbed by suitable resistors. See also BRAKE, Regenerative. Dynamic brakes may be used to control train speed and to brake a train to a low speed, after which air brakes may bring the train to a full stop.

Electro-pneumatic (pneumatic brake) - an automatic air brake that has electrically controlled valves to expedite applying and releasing the brakes.

Friction (mechanical brake) - a brake that presses brake shoes against the running wheel tread or pads against inboard or outboard disc surfaces.

Regenerative - a form of dynamic brake in which the electrical energy generated by braking is returned to the power supply line instead of being dissipated in resistors.

Track (electromagnetic brake, magnet brake) - a brake that consists of electromagnetic plates suspended above the track rail between the two axles of a truck. When the brake is activated, the plates drop onto the rails and exert braking by using powerful magnetic force that causes friction. The brake cannot be applied gradually and is used for emergency and holding, generally in conjunction with another braking system. This type of brake is required on all light rail vehicles and most streetcars.

BRAKE SHOE - The non-rotating portion of a tread or disc brake assembly. The shoe is pressed against the tread, disc, or drum when the brake is applied.

Closed Loop - Braking under continuous direction of the train control system.

Full service - See BRAKING, Maximum Service.

Maximum Service (full service braking) - in rail operations, a non-emergency brake application that obtains the maximum brake rate that is normally regarded as comfortable for passengers and consistent with the design of the primary brake system.

Open-loop - unmodulated braking without feedback control from the train control system.

Service (service application) - in rail operations, retardation produced by the primary train braking system at the maximum rate of retardation regarded as comfortable for repeated use in service stopping.

BRAKING, DYNAMIC - An electric primary braking system whereby the current derived from the motors, acting as generators, is modulated to provide controlled braking.

BRAKING, EMERGENCY - An irrevocable open-loop braking system designed

to insure fail safe brake application.

BRAKING, FULL SERVICE - A non-emergency brake application which obtains the maximum brake rate consistent with the design of the primary brake system(s).

BRAKING, OPEN LOOP - Braking without feedback control.

BRAKING, PROGRAMMED - Closed-loop braking with the requirement that a stop be completed at a designated point within a specified distance.

BRAKING RATE (See RATE, BRAKE) - The negative time rate of change of speed of vehicle as produced solely by the action of its braking system(s).

BRAKING SYSTEM - Those elements on board a train and their interconnections that produce speed retardation in response to a control signal.

BREAKDOWN (See FAILURE) - An inability to perform an intended function.

BUMPING POST SIGNAL - A signal to advise that a bumming post at a temporary or permanent end of the track is ahead.

BUNCHING - With transit units, a situation that occurs when passenger demand is high and dwell times at stops are longer than scheduled. Headways become shorter than scheduled, and platoons of transit units (vehicles or trains) develop, with longer intervals between platoons. The same effect (one transit unit caught by the following) can also be caused by lack of protection from general road traffic congestion or by traffic signal timing. Bunching can become cumulative and can result in delay to passengers and unused capacity.

BURN-IN - A conditioning procedure involving the operation of items in specified environmental conditions for the purpose of eliminating early failures by aging or stabilizing the items prior to operational use.

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C

C&C - Command and Control

CAB - The space or compartment in a locomotive or a powered rail car containing the operating controls and providing shelter and seats for the engine crew or motor operator.

CAB SIGNAL (See SIGNAL, CAB) - A signal in the train operator's cab which conveys the automatic block aspects and indicates the prevailing speed command.

CAB SIGNAL INDICATOR - A signal indicator located in the engine control compartment displaying the maximum speed for the movement of a train, used in conjunction with interlocking signals and either in conjunction with or in lieu of block signals.

CAB SIGNAL MODE (See MODE, CAB SIGNAL) - A form of manual train control wherein the operator controls the speed of the vehicle in accordance with signal aspects displayed on the cab signal indicator.

CALIBRATION - 1. Reconciliation of an instrument with an established standard. 2. In modeling, the procedure used to estimate the parameters of a model or to adjust a model to replicate actually measured conditions.

CAM CONTROLLER - A device to regulate direction, accelerating, running, and braking of an electric vehicle. Cams on a rotating shaft open or close spring-loaded contacts that make or break electric circuits between the power supply and the traction motors.

CAPABILITY - The ability of equipment or systems to perform an intended task when in a non-failed state.

CAPACITY -

Crush (crush load) - the maximum feasible passenger capacity of a vehicle, that is, the capacity at which one more passenger cannot enter without causing serious discomfort to the others.

Fleet (rolling stock capacity) - the total number of passenger spaces in all vehicles of a transit fleet.

Line - The number of vehicles per unit time, or passengers per unit time, that flow in one direction between two points along a line.

Seating (seated capacity) - the number of passenger seats in a vehicle.

Standing - the number of standing passengers that can be accommodated in a vehicle under specified comfort standards, expressed in area per standee.

Vehicle - The passenger capacity pertinent to specified loading conditions.

CAR - Any unit of equipment designed to be hauled by locomotives, or any unit of on-track work equipment such as a track motorcar, a highway-rail car, on-track push car, on- track crane, on-track ballast tamping machine, etc.

Cable - an individually controlled rail passenger vehicle operating in mixed street traffic and propelled by gripping a continuously moving cable located in an underground slot between the rails. The cable (which can draw many cable cars simultaneously) is powered by a large stationary motor at some central location instead of aboard the vehicle.

Car body - in passenger transportation, that portion of a rail car that carries people.

Double-deck - a bi-level rail car with a second level that covers the full width of the car but may or may not extend the full length.

Dual-powered turbo-electric - a commuter railroad car capable of either running on electric power from a third rail or overhead wire or self-propulsion by a generator driven by a gas turbine.

Electric rail - a rail car powered by current from a conduit along the track. The conduit is usually an overhead wire or third rail. See also CAR, Rectifier electric motor.

Gallery - a bi-level rail car that has seating and access aisles on a second level along each side of an open well. Tickets of passengers on the second level can be inspected or collected from the lower level.

Light rail (LRV, light rail vehicle) - a rail vehicle similar to a streetcar. It may be larger, however, and is often articulated. A light rail car is capable of boarding and discharging passengers at either track or car-floor level.

Multiple-unit (MU) - a powered rail car arranged either for independent operation or for simultaneous operation with other similar cars, when connected to form a train of such cars. It may be designated as DMU (diesel multiple-unit) or EMU (electric multiple-unit), depending on the source of power.

Rail diesel (RDC, diesel rail car) - a self-powered rail car that usually has two diesel engines and can usually operate in multiple units (diesel multiple-unit car).

Rail motor (motor car, powered car, self-powered car, self-propelled car) - a rail car that is propelled by a motor or engine located on the car itself. It can often be operated in multiple units (multiple-unit car). Common types are electric (electric rail car), which receives current either from a third rail or from an overhead wire, and diesel (rail diesel car).

Rail rapid transit (rapid transit car, subway car) - a rail car for rapid transit systems. It is bi-directional, usually powered, and equipped with a control cab at one or both ends. It may be designed to operate in single or multiple units. It has two to five double doors per side, designed for fast boarding and alighting from high-level platforms.

Rectifier electric motor - a rail car that collects propulsion power from an alternating-current distribution system and converts it to direct current for application to direct current motors by means of rectifying equipment carried by the rail cars. The car may be defined by type of rectifier used, for example, ignitron electric car.

Single-unit (SU) - a powered rail car, equipped with a control cab at one or both ends, that operates alone.

Track - a self-propelled rail car (e.g., burro crane, highway rail car, detector car, weed burner, tie tamper) that is used in maintenance service and that may or may not operate signals or shunt track circuits.

Trolley - 1. A local term for a streetcar. 2. Recently, also a local term for a bus with a body simulating that of an old streetcar.

CAR (See TRANSIT CAR, RAIL RAPID) - An electrically propelled and passenger carrying rail vehicle, i.e., a vehicle running on rails, for example, streetcar, rapid transit car, railroad car.

CATASTROPHIC - A hazard severity category identified as "Category I, Catastrophic". Category I is defined as failure conditions which could result in a large number of injuries and/or fatalities, and/or loss of system. For example, braking system loss at high speeds is considered a catastrophic hazard because it is assumed a collision could result. Single failures that result in catastrophic failure conditions are not acceptable.

CATENARY SYSTEM - That form of electric contact system in which the overhead contact wire is supported from one or more longitudinal wires or cables (messengers), either directly by hangers (simple catenary) or by hangers in combination with auxiliary conductors and clamps (compound catenary). Attachment of the contact wire to the messenger is made at frequent and uniform intervals to produce a contact surface nearly parallel to the top of the track rails.

CCTV - Closed Circuit Television

CENTRAL CONTROL - The place where train control and train supervision is accomplished for the entire system.

CENTRAL LINE SUPERVISION (See AUTOMATIC TRAIN SUPERVISION (ATS) - That subsystem within the automatic train control system which monitors the system status and provides the appropriate controls to direct the operation of trains in order to maintain intended traffic patterns and minimize the effect of train delays on the operating schedule.

CENTRALIZED TRAFFIC CONTROL (CTC) - A block signal system within

I which train movements are authorized by block signals whose indications are

monitored and controlled at a central control.

CHECK - In transit operations, a record of the passenger volume on all transit units that pass a specific location or time point (also known as a passenger riding court or check), the actual time the unit passes it (also known as a schedule check), the number of passengers who board and alight at each stop on a route or line (also known as an on-and-off count or check), or any combination of these items. The checker may ride the transit unit (an on-board check), follow it in another vehicle, or check the transit units from a particular location (a point or corner check).

CHECKED REDUNDANCY - A characteristic of a system which ensures that the probability of any malfunction is controlled to produce a risk comparable to fail safe.

CHECKER - In transit operations, a person who observes and records passenger counts, timing, speeds, vehicle counts, schedule adherence, or other data useful in transit planning and scheduling. The position may be further specified as schedule checker, traffic checker, and so on.

CHOPPER - A solid-state electronic device that controls electric current flow to traction motors by very rapidly turning the power on and off, resulting in gradual vehicle acceleration at reduced current use.

CIRCUIT - Electric train line - (See ELECTRIC TRAIN LINE CIRCUIT.)

CIRCUIT, CHECK-IN/CHECK-OUT - An electrical circuit that detects and transmits the front end of the train entrance into, and the rear of the train departure from a block for the purposes of determining block occupancy.

CIRCUIT, CODED TRACK - A track circuit in which the energy is varied or interrupted periodically.

CIRCUIT, NON-VITAL - Any circuit the function of which does not directly affect

the safety of train operations.

CIRCUIT, SHUNT FOULING - The track circuit in the fouling section of a turnout, connected in multiple with the track circuit in the main track.

CIRCUIT, TRACK - An electrical circuit of which the rails of the track form a part.

CIRCUIT, VITAL - Any circuit which affects the safety of train operations.

CIVIL SPEED LIMIT - In rail operations, the maximum speed authorized for each section of track, as determined primarily by the alignment, profile, and structure.

CIVIL SPEED LIMIT (See SPEED LIMIT, CIVIL) - The maximum speed allowed in a specified section of track as determined by physical limitations of the track structure, train design, and passenger comfort.

CLEARANCE - The distances between specified points along the track and specified points on moving vehicles.

CLEARANCE DIAGRAM - A diagram which establishes the minimum safe distance between all points on a moving vehicle and fixed wayside structures or appurtenances.

CLOSED-LOOP BRAKING - See braking, closed-loop.

CLOSED CIRCUIT PRINCIPLE - The principle of circuit design using a normally energized electric circuit which, on being interrupted or de-energized, will cause the controlled function to assume its most restrictive condition.

CLOSED LOOP -The principle of feedback control in which the response of a system is continuously compared with the controlling signal to generate an error signal.

CODE, COMMAND - A transmitted vital coded signal to initiate action.

CODE, STANDARD - The operating, block signal, and interlocking rules of the Association of American Railroads.

COG RAILWAY (rack railway) - A rail transportation mode with auxiliary or full traction provided by a geared wheel in the middle of a powered axle that is engaged with a rack (toothed bar) installed along the track center. This system is used to overcome steep gradients.

COLLECTOR, CURRENT - (See CURRENT COLLECTOR.)

COLOR LIGHT SIGNALS (See SIGNAL, COLOR LIGHT) - Signals which display aspects by means of lighted color lenses.

COMMAND AND CONTROL SYSTEM (C&C) -in rail systems, any means of adjusting and maintaining prescribed head ways; effecting starting and stopping, merging, and switching; and controlling other such functions. It is usually considered to include transit unit (car or train) protection, transit unit operation, and line supervision to ensure safe movement of the transit unit within the system. (See also CONTROL SYSTEM, WAYSIDE.)

COMMAND CENTER (See CENTRAL CONTROL) - That place from where train control or train supervision is accomplished for the entire transit system; the train command center.

COMMUNICATION SYSTEM - Those elements and their interconnection which permit voice, data, or video interchange of information between system functions separated by distance.

COMMUTE - Regular travel between home and a fixed location (e.g., work, school). The term is often applied only to travel in the direction of the main flow of traffic, to distinguish from reverse commute.

COMMUTER - A person who travels regularly between home and a fixed location (e.g., work, school).

COMPONENT - An article which is a self-contained element of a complete operating unit and which performs a function necessary to the operation of that unit.

CONDUCTOR - 1. In rail transit operations, the operating employee who may control the doors on rail transit vehicles, or who may have fare-collecting duties, or both. 2. In railroad operations, the operating employee in charge of the train and train crew. 3. In some bus operations, an operating employee (other than the bus driver) who collects fares and may control doors.

CONFIGURATION MANAGEMENT - A process to assure that all documentation which describes a system and its various components is current and reflects the actual functional and physical characteristics of the system throughout its life cycle.

CONSIST - In rail systems, the makeup or composition (number and specific identity) of individual units of a train.

CONSTRUCTION SAFETY - The optimum degree of safety within the constraints of construction effectiveness, time and cost through specific application of safety management throughout all phases of the construction.

CONTACT RAIL (See RAIL, THIRD) - A rail mounted on insulators alongside the running rail which provides traction power for train propulsion.

CONTACT WIRE (trolley wire) - An overhead electric conductor that supplies power to streetcars, trolley buses, and similar vehicles.

CONTACT - A conducting part which co-acts with another conducting part to open or close an electrical circuit.

CONTACT, BACK - A part of a relay against which, when the relay coil is de-energized, the current-carrying portion of the movable neutral member rests so as to form a continuous path for currents.

CONTACT, FRONT - A part of a relay against which, when the relay coil is energized, the current-carrying portion of the movable neutral member is held so as to form a continuous path for currents. CONTACT, NORMAL - A part of a polarized relay against which, when the relay is energized with a voltage of normal polarity, the current-carrying portion of the movable pole member rests so as to form a continuous path for currents.

CONTACT, REVERSE - A part of a polarized relay against which, when the relay is energized with a voltage of reverse polarity, the current-carrying portion of the movable pole member rests so as to form a continuous path for currents.

CONTINUOUS BRAKE - (See BRAKE, CONTINUOUS.)

CONTINUOUS TRANSIT SYSTEM - (See TRANSIT SYSTEM, CONTINUOUS.)

CONTRACT DATA REQUIREMENTS LIST (CDRL) SUBMITTAL - Evidence submitted by a contractor showing that the material and equipment they furnish in accordance with the contract specifications meets the applicable standards named in the specifications. The CDRL itself is originally part of the contract specifications.

CONTROL CENTER - That place from where train control or Train Supervision is accomplished for the entire transit system; the train command center.

CONTROL SYSTEM -

Asynchronous network - a non-synchronized electronic system for controlling headways. The transit unit (car or train) position is not rigidly controlled as a function of time. The longitudinal control of the transit unit is independent of line traffic when it is not in close proximity to another transit unit but usually becomes a car-following procedure when transit units are close to each other.

Automatic block signal (ABS) - a system of governing train separation in which the signals are controlled by the trains themselves. The presence or absence of a train in a block is determined by a track circuit. If the circuitry fails, a restrictive signal is displayed.

Augmented block guidance - an automated block control system for transit units (cars or trains) with short headways.

Cab signal - in rail systems, a signal located in the cab, indicating a condition affecting the movement of a train and used in conjunction with interlocking signals and in conjunction with or in lieu of block signals.

Centralized traffic (CTC) - in rail systems, a traffic control system in which signals and switches are controlled from a remotely located (centralized traffic control) panel.

Continuous train (continuous inductive train control) - a locomotive or self-propelled car apparatus that is constantly in contact with the track circuit and is immediately responsive to a change of conditions in the controlling section that affects train movement.

Fixed block - an automatic train control system that records the presence of a train (or a part of it) in each track section (block) and activates the signals on the line to indicate the block is occupied. In some cases, a following train is prevented from entering the block by a forced emergency stop.

Manual block - a system of manually governing train movement in a block or a series of consecutive blocks by means of signals, train orders, telephone, or radio.

Moving block (dynamic block control) - an automatic train control system that spaces trains according to their location and (sometimes) their relative velocity, stopping performance, and a prescribed factor of safety.

Moving slot (point-follower control system, moving point control system) - a position control system in which the transit unit (car or train) synchronizes itself with the programmed trajectory of one of a set of moving points or slots monitored by a central computer; see also CONTROL SYSTEM, Synchronous network.

Multiple-unit - a system that controls the operation of two or more motor cars in a train through the simultaneous control of the train by one operator.

Quasi-synchronous network - an electronic system for controlling headways in which transit units (cars or trains) can be directed to move from one slot to another; see also CONTROL SYSTEM, Synchronous network.

Synchronous network - a position control system in which the transit unit (car or train) synchronizes itself with the pre-programmed trajectory of one of a set of moving points or slots monitored by a central computer. A complete, conflict-free trajectory must be available for the assigned slot from original to destination before the transit unit is permitted to depart. See also CONTROL SYSTEM, Moving slot.

Wayside - a command and control system in which transit units (cars or trains) are controlled by electronic or mechanical devices along the track or other guideway.

CONTROL, BRAKE - That system which generates control signals to the braking system that result in a desired application of brakes.

CONTROL, CONTINUOUS - The continuous generation of, and response to, control signals.

CONTROL, DEADMAN - A pressure or activity actuated device to detect inattention or disability of a train operator.

CONTROL, DISCRETE - The imposition of control signals at discrete points with respect to time or location.

CONTROL, EMERGENCY - The automatic or manual generation of priority control signals within the system in direct response to non-normal conditions.

CONTROL LIMIT - Extremes of the range over which a control signal has effect.

CONTROLLED ACCESS - (See ACCESS, LIMITED.)

CONTROLLED SIDINGS - A designated siding, the entrance and exit of which are governed by home signals.

CONTROLLER, MASTER -The device which generates local and train-lined control signals to the propulsion system or brake system.

CONTROLLER, SWITCH CIRCUIT - A device for opening and closing electric circuits, operated by a rod connected to a switch, derail, or movable point frog.

CONVENTIONAL RAIL TRANSPORT - Transportation systems that consist of steel-wheeled trains running on duo-rail tracks. Trains may be self-propelled or hauled by locomotive, with diesel or electric propulsion.

CONVEYANCE - A means of carrying or transporting goods, people, or both.

CORDON COUNT - In planning, a count of vehicles and people across a designated (cordon) line to determine the total flow (people and vehicles by mode and time period) into and out of the study area.

CORRECTIVE ACTION PLAN - A plan prepared by the Branch (internal audit) or transit system (external audit) describing the actions it will take to implement corrective actions for any audit item found to be in Exception during an audit.

COST RECOVERY RATIO - The ratio of total revenues to total costs; the inverse of operating ratio. It is often used for evaluation of alternative plans.

COUNT - 1. In transportation, a process that tallies a particular movement of people or vehicles past a given point during a stated time period. It may be a directional or a two-way value and is also known as a traffic count. 2. In transportation, a volume of people or vehicles.

COUPLER - A device for connecting one rail vehicle to another. The mechanism is usually placed in a standard location at both ends of all rail cars and locomotives.

Automatic - 1. A coupler that operates automatically. It may also be capable of uncoupling automatically. 2. An automatic connector that joins electric or pneumatic train lines together between rail cars.

COUPLING -

Magnetic - coupling achieved by the use of energized electromagnets.

CPR - Cardio - Pulmonary Resuscitation

CRASH SAFETY - A system characteristic that allows the system occupants to survive the impact of a crash and to evacuate the system after potentially survivable accidents.

CRASH WORTHINESS - The capacity of a vehicle to act as a protective container and energy absorber during impact conditions.

CRITERIA - A document or drawing containing actions or features that are recommended and should be implemented but maybe modified or waived with rationale. Criteria may be adopted as a standard or code.

CRITERIA CONFORMANCE SAFETY VERIFICATION (CCSV) - One of the steps of safety verification. This is a form signed off by the engineers, the BATC project managers, and the BART project managers verifying that the contract has met all the safety criteria for that contract or that all exceptions have been satisfactorily resolved.

CRITICAL - A hazard severity category identified as "Category II, Critical". Category II is defined as failure conditions which could result in significant system damage or severe injury on one or more persons.

CRITICAL/CATASTROPHIC ITEMS LIST (CCIL) - A listing of Category I (Catastrophic) and Category II (Critical) hazards. This list is usually compiled from all hazards identified in analysis. It is used to track resolution of all identified hazards. Category I and Category II hazards identified from sources other than analysis are also contained in the project CCIL. (Also see HAZARD SEVERITY CATEGORY.)

CRITICAL DEFECT - A defect that judgment and experience indicate could result in hazardous or unsafe conditions for individuals using or maintaining the product or could result in failure in accomplishment of the ultimate objective.

CRITICAL FUNCTION LIST - A listing of those functions whose failure would cause system degradation below an acceptable level.

CRITICALITY - Assignment of relative importance to hardware or systems.

CROSSING -

Grade - a crossing or intersection of highways, railroad tracks, other guideways, or pedestrian walks, or combinations of these at the same level or grade.

Railroad grade - the area where a road and a railroad cross at the same level, within which are included the railroad tracks, roadway, and roadside facilities for both road and rail traffic traversing that area.

CROSS (EQUALIZER) BOND - An electrical connection from one track to another track to distribute traction power return currents.

CROSS PROTECTION - A means to prevent the undesired (or unintended) operation of a signal switch, movable point frog, or derail as the result of a cross in electrical circuits.

CROSSING -

Track (railway crossing) - an assembly of rails and frogs that allows crossing of two tracks at grade.

CROSSING AT GRADE - An intersection of two or more tracks at the same elevation; an intersection of one or more tracks with a roadway.

CROSSOVER -1. In rail systems, a track with two switches that connects two parallel tracks. 2. Pedestrian or vehicular links (at grade or grade separated) across a transportation facility.

CROSSOVER [RAIL] - Two turnouts, with track between the frogs, arranged to form a continuous passage between two parallel tracks.

CROSSTIE (railroad tie, tie) - The transverse member of the track structure to which the rails are fastened. Its function is to provide proper gauge and to cushion, distribute, and transmit the stresses of traffic through the ballast to the roadbed.

CTC Centralized Traffic Control; see CONTROL SYSTEM, CENTRALIZED TRAFFIC.

CTDIS - Computerized Train Dispatch Information System

CULVERT - Any drainage or service structure under a roadway or guideway with a clear opening of 20 ft (6 m) or less measured along the center of the roadway or guideway.

CURRENT COLLECTOR - The mechanical component on an electric rail car that makes contact with the conductor that distributes the electric current; see also OVERHEAD CONTACT SHOE, PANTOGRAPH, THIRD-RAIL SHOE, and TROLLEY POLE.

CURRENT, FOREIGN (STRAY CURRENT) - Stray electric currents which are not a part of the system but which may affect a signaling system or contribute to galvanic corrosion.

CURRENT, LEAKAGE - An electric current which flows through or across the surface of insulation when a voltage is impressed across the insulation.

CURRENT OF TRAFFIC - The movement of trains on a main track in one direction specified by special instructions.

CURRENT OF TRAFFIC (See DIRECTION, NORMAL) - The designed predominant direction of train traffic as specified by the rules.

CUT-AND-COVER - A method of construction that consists of excavating the terrain from ground level, placing a structure in the excavation, and then filling over the structure.

CUT LINE - 1. In planning, an imaginary line placed at a strategic location to intercept all the links in an identified corridor. 2. In transit operations, the transverse division of a route as by a planned service change or an emergency.

CUT-SECTION - A location other than a signal location where two adjoining track circuits end within a block.

CWR - Continuous Welded Rail; see RAIL, Continuous welded.

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D

DASH SIGN - A large card placed on top of the dashboard and visible through the bus windshield, in addition to or instead of a head sign, usually denoting the type of service or destination.

DATA BASE - 1. A collection of data from which information is derived and from which decisions can be made. 2. A non-redundant collection of data items processable by one or more computer applications.

DC - Direct Current

DE-ENERGIZE - To deprive an electro-receptive device of its operating current.

DEAD SECTION - A section of track, either within a track circuit or between two track circuits, the rails of which are not part of a track circuit.

DEADHEAD - 1. To move a revenue vehicle in other than revenue service, for example, from one garage to another or from the end of a line to a garage. Such movement may include people using an employee pass and an occasional revenue passenger riding on an incidental basis. Also known as deadheading. 2. A non-fare-paying passenger, most commonly a transit system employee traveling to work using a pass.

DEADMAN CONTROL - A pedal, handle, or other form of switch, or combination thereof, that the operator must keep in a depressed or twisted position while a rail vehicle (or train) is moving. If the control is released, the power is cut off and the brakes are applied.

DECELERATION - Decrease in velocity per unit time; in transit practice, often measured in feet per second squared (meters per second squared) or, in the United States, miles per hour per second. DECELERATION RATE (See RATE, DECELERATION) - The net negative time rate of change of speed of a vehicle resulting from the summation of all forces acting upon it.

DECK - In transit systems, the floor of a rail car, bus, or boat.

DECODER - A device which transforms a received signal into a data format.

DEFICIENCY, DESIGN - Any design characteristic which does not meet specified criteria.

DEGRADATION - Failing from an initial level to a lower level in quality or performance.

DEMAND CURVE - The quantities of a given product or service that people are willing to purchase as a function of its given unit cost.

DEPARTMENT TEST - Operational test made on complete train in a yard or on a transfer track before permitting train to operate on a main line.

Test - Operational test made on complete train in a yard or on a transfer track before permitting departure train to operate in cab signal or automatic mode.

DEPLOYMENT, VEHICLE - Strategy of locating vehicles, ready for service, at

points which permit utilization for emergency situations.

DERAIL - l. To run off the track. 2. A track safety device designed to guide a rail car off the rails at a selected spot to prevent collisions or other accidents, commonly used on spurs or sidings to prevent unattended rolling cars from fouling the main line; also known as a derailer.

DERAILMENT - an instance of the wheels of a rail vehicle coming off the track.

DESIGN PHASE - The phase of the life cycle which begins at the onset of preliminary design and ends when the design is finalized and ready to go into production.

DESIGN SAFETY - Safety achieved by the integration of safety features into the system design characteristics to prevent or minimize the probability of operation in an unsafe manner.

DESIGNATED AUTHORITY - The titled position charged with responsibility of supervising, authorizing, directing, and/or controlling train movements and other facets of operations often from a central location. The local company title should be used in place of "designated authority.

DESTINATION SIGN - A sign on a transit unit (vehicle or train) indicating the route or line number, direction, destination of the unit, or any combination thereof. Destination signs are most commonly located on the front of the transit unit but may also be located on the back, side, or both. See also HEAD SIGN.

DETECTION DEVICES - Sensors used to detect and monitor the status of certain systems, e.g., open or closed doors, component temperatures, flow rates, etc. The status is usually displayed on control consoles.

DETECTOR, GROUND - A device for detecting a ground on an electrical circuit.

DETECTOR, POINT - A circuit controller which is part of a switch operating mechanism and operated by a rod connected to a switch, derail, or movable point frog to indicate that the point is within a specified distance of the stock rail.

DETECTOR, TRACK CIRCUIT - A track circuit, within an interlocking which, when occupied by a train, prevents the position of a track switch from being changed.

DETOUR - A temporary change in a portion of a transit route or highway; see also REROUTE.

DEVICE, ACKNOWLEDGING - A manually operated device by means of which, on a train equipped with automatic train stop or train control, an automatic brake application can be forestalled, or on a train equipped with automatic cab signaling, the sounding of the cab indicator can be silenced.

DHA - Detailed Hazard Analysis

DIRECTION, NORMAL - The designed predominant direction of train movement as specified by the rules.

DIRECTION, REVERSE - Train movement in the direction opposite the normal direction.

DIRECTIONAL SPLIT - The proportional distribution between opposite flows of traffic on two-way facilities.

DISPATCH POINT - 1. The location at which operating employees receive their assignments. 2. The location at which trips are started or restarted.

DISPATCHER - 1. In bus operations, the individual who assigns buses to runs, makes up work assignments to fill runs, directs the operators at the start of their assignments, and in some cases, maintains a constant awareness of status of the operation, via radio, telephone, or other means. 2. In rail operations, an operating person within a control center whose function it is to dispatch transit units (cars or trains), monitor their operation, and intervene in the event of disruption of schedule or when any change in service or routing is required. 3. In demand-responsive transportation, the person who assigns the vehicles to customers and notifies the appropriate drivers and who may schedule and route vehicles and monitor their operation.

DISPATCHER, AUTOMATIC TRAIN - A programmable device whose function it is to dispatch trains on predetermined schedule. An operating person, within a control center, whose function it is to dispatch trains, monitor train operation, and to intervene in the event of disruption of schedule or when any change in service or routing is required.

DISPATCHING - 1. In rail operations, the process of starting a transit unit (car or train) into service from a terminal, yard, or transfer track. 2. In demand-responsive transportation systems, the process of relaying service instructions to drivers. The procedure may include vehicle scheduling, routing, and monitoring, and it can be manual or partly or fully automated. 3. The relaying of service instructions to vehicle drivers or operators.

DISTANCE -

Linked trip - (See TRIP DISTANCE, Linked.)

DISTANCE, STOPPING - The maximum distance on any portion of any track which any train, operating on such portion of railroad at its maximum authorized speed, will travel during a full service application of the brakes, between the point where such application is initiated and the point where the train comes to a stop. (Also referred to as Safe Braking Distance)

DISTANT SIGNAL - A fixed signal used to govern the approach to a home signal.

DMU - Diesel Multiple Unit car; see CAR, Multiple-unit.

DOOR CONTROL - Circuitry, including such safeguards and interlocks as

required, which operates to open and close doors.

DOUBLE-ENDED TRANSIT UNIT (bidirectional transit unit) - A rail car or train with an operating cab at each end.

DOUBLE-SIDED LINEAR INDUCTION MOTOR - (See MOTOR, Double-sided linear induction.)

DOWN TIME - The total time during which the equipment is not in acceptable operating condition. Down time starts with a failure event and ends at the completion of repair and functional checks/inspections.

DOWNGRADING - Reassignment of an employee to a task or job that requires lower skills and usually has a lower rate of pay.

DRIVING WHEELS - Wheels that are powered by a motor or engine and that provide the tractive effort, through contact with the running surface, that propels the vehicle.

DROPAWAY (RELEASE VALUE) -The electrical value at which the movable member of an electromagnetic device will move to its de-energized position.

DSLIM - Double-Sided Linear Induction Motor

DUAL CONTROLLED SWITCH - An interlocked switch that by means of a selector lever may be hand or motor operated. Note: Normal position of selector lever is in motor position.

DUPLEX - Capable of transmitting and receiving.

DWELL TIME - The total time from the instant that a train stops in a station until

the instant it resumes moving.

DYNAMIC ROUTING - In demand-responsive transportation systems, the process of constantly modifying vehicle routes to accommodate service requests received after the vehicle began operations, as distinguished from predetermined routes assigned to a vehicle.

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E

E&H - Elderly and Handicapped.

EAS - Emergency Alarm Station

EASEMENT - A right acquired by one party to use or control property belonging to another party for a designated purpose, such as public utilities, streets or highways, transit lines.

EFFECTIVENESS - 1. In transportation, the correspondence of provided service to intended output or objectives, particularly the character and location of service; in other words, producing the intended result (doing the right things). 2. In transit, the degree to which the desired level of service is being provided to meet stated goals and objectives; for example, the percentage of a given service area that is within the desired 1/4 mi (0.4 km) of a transit stop.

EFFICIENCY - The ratio of output (e.g., level of service provided) to input (e.g, cost or resource usage), that is, providing the desired result with a minimum of effort, expense, waste, and so on (doing things right).

ELDERLY AND HANDICAPPED (E&H) - People who may have special needs for services such as transportation. Transportation especially provided for their benefit is called elderly and handicapped (E&H) transportation. Transit operations may include discounted fares (E&H fares) for their benefit. The minimum age for elderly people varies by the program (e.g., 55+, 60+, 65+). See also HANDICAPPED.

ELECTRIC BRAKE - (See BRAKE, Dynamic.)

ELECTRIC INCLINE RAILWAY - A railway in which vehicles are carried or conveyed by an electric hoist along inclined tracks. The hoist carries a single car, with or without counterweights, or two cars in balance. The system is used to overcome steep gradients. See also FUNICULAR RAILWAY.

ELECTRIC TRAIN LINE CIRCUIT - A continuous electric circuit between all units of the train. The circuit is provided with control stations to permit the control of traction motors and other equipment from any operator's cab on the train (or, in special cases, from one cab only).

ELECTRIC LOCK SWITCH - A hand-operated switch equipped with an

electrically controlled device which restricts the movement of the switch.

ELECTRIFICATION (railway electrification) - In rail systems, a term used to describe the installation of overhead wire or third-rail power distribution facilities to enable operation of electrically powered transit vehicles.

ELEMENT, WAYSIDE (ROADWAY) - That portion of the wayside apparatus of an automatic train stop, train control, or cab signal system, such as an electric circuit, inductor, magnet, ramp, or trip arm, to which the carborne apparatus of such system is directly responsive.

EMERGENCY - A situation which is life threatening or which causes damage on or in any transit facility, trainway, vehicle or bus.

EMERGENCY BRAKE APPLICATION - An irrevocable open-loop braking system designed to insure fail safe brake application.

EMINENT DOMAIN - The power to take private property for public use without the owner's consent, on payment of just compensation; see also CONDEMNATION.

EMPLOYEE, OPERATING - The employee of a transit system having direct and supervisory responsibility for the movement of trains.

EMU - Electric Multiple Unit

ENCODER - A device that transforms the format of the supplied data into the format required for transmission.

ENGINE - A unit propelled by any form of energy, or a combination of such units operated from a single control, used in road or yard service.

Radio-controlled (slave unit) - in passenger trains, an unmanned propulsive unit within a train that is separated by rail cars from the lead unit but controlled from it by radio signals.

Steam - an engine driven or worked by steam; specifically, a reciprocating engine that has a piston driven by steam in a closed cylinder.

Turbine - a rotary engine actuated by the reaction or impulse or both of a current of fluid or gas subjected to pressure. A turbine is usually made with a series of curved vanes on a central rotating spindle.

ENVIRONMENT - The physical conditions that exist within a given area that will be affected by a proposed project, including land, air, water, minerals, flora, fauna, ambient noise, and objects of historic or aesthetic significance.

ENVIRONMENTAL IMPACT STATEMENT (EIS, 102 STATEMENT) - A comprehensive study of likely environmental impacts that will result from major federally-assisted projects. An EIS is required by the National Environmental Policy Act of 1969.

EOIS - Electrically Operated Isolating Switches

EQUIPMENT CONSIST - A train, locomotive(s), cut of cars, or any single car not coupled to another car or locomotive.

EQUIPMENT FAILURE - The state in which equipment no longer meets the minimum acceptable specified performance and cannot be restored through operator adjustment of controls.

EQUIPMENT, WAYSIDE (See WAYSIDE EQUIPMENT) - Train control or movement apparatus which is located along the track or wayside as opposed to the control center or other remote location.

ESCALATOR CLAUSE - A provision in a contract that stipulates that wages or prices are to be automatically increased or decreased at specific times according to a schedule that is usually related to changes in the cost of living (cost-of-living allowance, COLA) as measured by a designated index or other standard (e.g., the consumer price index). The provision may also apply to any tie between employer benefits and the cost of living, as in a pension plan.

EXCEPTION - An item on an audit checklist which is found during an audit to need improvement in order to attain full compliance with the provisions of the System Safety Program Plan.

EXCLUSIVE TRANSIT FACILITIES - Transportation system infrastructure elements that are set aside for the use of transit vehicles only. Examples include some freeway ramps, bus lanes, off-street bus loading or unloading areas, and separated and fully controlled rights-of-way.

EXTRA BOARD - Means the roster or list of all operators who by virtue of length of service, or by choice, do not have a regularly assigned run. Part-time operators shall not be considered extra-board operators.

EXTRA TRAIN - A train not authorized by a timetable schedule. It must be designated as: EXTRA - For any extra train except passenger train extra, work train extra or track car extra; PASSENGER EXTRA - For passenger train extra; WORK EXTRA - For work train extra; TRACK CAR EXTRA - For track car extra.

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F

FACING MOVEMENT (See MOVEMENT, FACING) - The movement of a train over the points of a switch which face in a direction opposite to that in which the train is moving.

FACING POINT LOCK - A mechanical lock, for a switch, derail, or movable point frog, comprised of a plunger stand and a plunger, which engages a lock rod attached to the switch point to lock the operated unit. A track switch the points of which face toward approaching traffic.

FAIL-SAFE - 1. Incorporating a feature that ensures that malfunctions that affect safety will cause the system to revert to a state that is safe. 2. A characteristic of a system and its elements, the object of which is to ensure that any fault or malfunction, will not result in an unsafe condition.

FAIL SAFE DESIGN - A design principle in which each of the elements which make up a system is analyzed to determine the potential consequence of failure of that element, alone or in combination with any or all other elements of the system, to ensure that a failure or a combination of failures will not result in an unsafe condition.

FAIL SAFE CIRCUIT - A circuit which must be energized to initiate a vital function and which verifies the proper condition of each element before being energized.

FAILED COMPONENT - A component which has ceased to perform its intended function.

FAILURE - An inability to perform an intended function.

FAILURE MANAGEMENT - Decisions, policies and planning which identify and eliminate potential failures.

FAILURE MODE AND EFFECT ANALYSIS (FMEA) - An inductive procedure in which potential malfunctions are identified and then analyzed as to their possible effects.

FAILURE ANALYSIS - The logical and systematic examination of a system to identify and analyze the probability, causes, and consequences of potential and real failure.

FAILURE ASSESSMENT - The process by which the cause, effect, responsibility, and cost of an incident (reported problem) in the transit system is determined and reported.

FAILURE, CRITICAL - A failure which could result in major injury or fatality to people or which could result in major damage to any system or loss of a critical function.

FAILURE CRITICALITY ANALYSIS - Study of the potential failures that might occur in any part of a system in relation to other parts of the system in order to determine the severity of effect of each failure in terms of a probable resultant safety hazard, and acceptable degradation of system performance.

FAILURE MECHANISM - The process which results in a part or equipment failure.

FAILURE MODE - The description of the manner in which a failure occurs, and

the operating condition of the equipment at the time of the failure.

FAILURE RATE - Rate at which failures occur as a function of time. If the failure rate is constant, it is frequently expressed as the reciprocal of mean-time between-failures (MTBF). Calculated for an article, it is the ratio of the total number of independent article failures to the total article operating hours.

FALSE OCCUPANCY - Indication of track occupancy when no train is present.

FALSE RESTRICTIVE (See ASPECT, FALSE RESTRICTIVE) - The aspect of a signal that conveys an indication more restrictive than intended.

FAR - Side stop - (See STOP, FAR-SIDE.)

FARECARD READER - A device that determines the value stored in a farecard when the farecard is inserted. A farecard reader may also be used for appropriately altering the value stored in a farecard. The device is usually used with a passenger turnstile or gate.

FARECARD - (See MAGNETIC FARECARD.)

FARE COLLECTION SYSTEM - The procedures and devices used to collect fares and to accumulate and account for fares paid.

Automatic (AFC) - the controls and equipment that automatically admit passengers on insertion of the correct fare in an acceptable form.

FARE-REGISTERING TURNSTILE (FAREGATE) - A turnstile that unlocks to allow a passenger to enter the paid area after a pass or farecard or the correct amount of money or tokens is inserted in it. It records the fares paid.

FARE RECOVERY RATIO (FAREBOX RECOVERY RATIO) - The ratio of fare revenue to operating expenses; see also OPERATING RATIO.

FAULT TREE ANALYSIS - A deductive procedure in which hazards are identified and then analyzed as to their potential causes.

FAULT - An undesired but functionally correct response in a system.

FAULT HAZARD ANALYSIS (FHA) - An analysis applied to elements of the system to identify hazards associated with component failures and fault conditions.

FIRST AID - Any one-time treatment and subsequent observation of minor scratches, cuts, burns, splinters and so forth, which do not require medical care even though such care is provided by a physician or registered professional personnel.

FIXED GUIDEWAY TRANSPORTATION (TRANSIT) SYSTEM - A transit system for the transporting of people by a conveyance, or a series of interconnected conveyances, which conveyance or series of conveyances is specifically designed for travel on a stationary rail or other guideway, whether located on, above, or under the ground.

FIXED SIGNAL (See SIGNAL, WAYSIDE) - A signal of fixed location along the track right-of-way.

FIXED WAY - All wayside appurtenances.

FLAG DROP CHARGE - The charge for an initial distance (usually specified by regulation) for taxi service. It is actually the minimum fare.

FLAG STOP SERVICE - See service, flag stop.

FLAGMAN - Personnel assigned to control movement of trains by the display of hand signals, flags, or lights.

FLASHER - In rail systems, the flashing light at railroad grade crossings that warns motorists, bicyclists, and pedestrians of approaching trains.

FLAT SPOT - Loss of roundness of the tread of a railroad wheel, caused by wheel sliding.

FLAT WHEEL - A rail car wheel that has a flat spot on the tread.

FLEET (rolling stock) - The vehicles in a transit system. Usually, "fleet" refers to highway vehicles and "rolling stock" to rail vehicles. Base-period-see Base-period fleet.

FLEETING - Manually established route selection, not canceled by the passage of a train.

FLOW RATE (rate of flow) - In transportation, the number of units (passengers or vehicles) passing a point on a transportation facility during some period of time, usually counted or re-computed in units per hour. For example, if 8 buses pass a point in the first half hour and 15 in the second, the volume for the hour is 23. However, the flow rate for the first half hour is 16 buses/hr, and for the second half hour the flow rate is 30 buses/hr. See also VOLUME.

FORESTALL - As applied to an automatic train stop or train control device: to prevent an automatic brake application by operation of an acknowledging device or by manual control of the speed of the train.

FOULING POINT - The location on a turnout, back of the frog, at which insulated joints or derails are placed, at or beyond the clearance point.

FPP - Fire Protection and Prevention

FRANCHISE -in transportation, the privilege or right granted a person, group, or organization by a government authority to provide general or specific transportation services, usually applicable to a geographically specified area.

FREEWHEELING - Running without influence of either the propulsion or braking systems, that is, with tractive and braking forces at zero.

FREQUENCY DISTRIBUTION, TRIP LENGTH - See trip length frequency distribution.

FRICTION FACTOR (F factor) - In a gravity model, the empirically determined value that expresses the effect of spatial separation between zones on trip interchanges.

FROG - A track component used at the intersection of two running rails to provide support and guidance for the wheels. It allows wheels on each rail to cross the other rail.

FROG, MOVABLE POINT - A frog equipped with points which are movable in the same manner as the points of a switch.

FUEL - In the conventional sense, a material or combination of materials that, when burned with air, produces heat and, often, explosive or mechanical energy.

Alternative - a liquid or gaseous non-petroleum fuel.

FULL CREW LAW - A law or regulation that requires a minimum number of workers to be present on particular job assignments.

FULL SERVICE BRAKE APPLICATION (See BRAKING, FULL SERVICE) - A non-emergency brake application which obtains the maximum brake rate consistent with the design of the primary brake system(s).

FUNICULAR RAILWAY - A passenger transportation mode consisting of a pair of rail vehicles (or short trains) permanently attached to two ends of the same cable, counterbalancing each other. It may have a single track with a turnout or a double track. This system is used to overcome steep gradients. See also ELECTRIC INCLINE RAILWAY.

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G

GATE - Entrance to a block or route where signal information is conveyed.

GATE, FIXED (END OF CAB SIGNAL/TRAIN CONTROL TERRITORY) - The limit of an interlocked route past which automatic operation of trains is never permitted.

Broad (wide gauge) - a rail track gauge that is more than 4 ft 8.5 in (1.435 m) wide. The distinction is often made that wide gauge is slightly greater but broad gauge is substantially greater than 4 ft 8.5 in. Narrow-a rail track gauge that is less than 4 ft 8.5 in (1.435 m) wide. Narrow - a rail track gauge that is less than 4 ft. 8.5 in. (1.435 m) wide.

Standard - a rail track gauge that is 4 ft. 8.5 in. (1.435 m) wide.

Track - the distance between the inside faces of the two rails of a track measured _ inch (1.59 cm) below the top of the rails and perpendicular to the gauge line.

Standard-a rail track gauge that is 4 ft 8.5 in (1.435 m) wide. Track-the distance between the inside faces of the two rails of a track measured _ inch (1.59 cm) below the top of the rails and perpendicular to the gauge line.

GAUGE LINE - A line _ in. (1.59 cm) below the top of the centerline of the head of the running rail along the side that is nearer the center of the track.

GENERAL NOTICE - A notice issued to employees by the General Superintendent-Transportation containing operating instructions and/or information as may be necessary.

GENERAL ORDER - An order issued to employees by the General Superintendent- Transportation which changes, adds to or annuls Operating Rules, timetable information or special instructions.

GOVERNOR - 1. A device that holds the speed of an engine approximately constant regardless of the load. 2. A device that keeps an engine from exceeding a predetermined speed.

GRADE CROSSING TRAFFIC CONTROL DEVICE - Any form of protective or warning device installed at a railroad or transit guideway grade crossing for the protection of highway or street traffic.

GRADE - Rise in elevation within a specified distance. As an example, a I-percent grade is a 1 ft (m) rise in elevation in 1 00 ft (m) of distance (measured horizontally).

GRADE SEPARATION - A vertical separation of intersecting facilities (road, rail, etc. ) by the provision of crossing structures.

GROUND DETECTOR (See DETECTOR, GROUND) - A device for detecting a ground on an electrical circuit.

GUARD (See CONDUCTOR) - An onboard train attendant whose function is to operate doors and otherwise assist in passenger movement and safety.

GUARDRAIL - 1. In rail construction, a rail or other device that is laid parallel to the running rails of a track to prevent derailment or to hold the wheels in alignment and prevent their flanges from striking the points of turnouts, crossing frogs, or the points of switches. 2. In highway construction, traffic barriers used to prevent errant vehicles from leaving their designated areas and striking fixed objects or entering hazardous areas.

GUIDEWAY - In transit systems, a track or other riding surface (including supporting structure) that supports and physically guides transit vehicles specially designed to travel exclusively on it.

Elevated - a grade-separated guideway on a structure that provides overhead clearance for vehicles that operate on the prevailing surface of the terrain; see also AERIAL STRUCTURE.

Open cut - a guideway below the prevailing surface of the terrain in a trench-like excavation (cut).

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H

HAIL - A hand or voice signal (or both) used to request a cruising vehicle to stop and accept passengers.

HAND BRAKE - A braking device manually applied to an already stopped train to prevent rolling.

HAND-OPERATED SWITCH - A switch which must be aligned by hand before a train or engine makes a trailing point movement through the switch.

HAND SIGNAL (See SIGNAL, HAND) - A manual signal used to govern the movement of trains.

HAND-THROWN SWITCH (See SWITCH, HAND OPERATED) - A switch which can only be operated manually.

HANDBOOK OF RULES - A set of codified regulations and procedures by which operating personnel are governed.

HANDICAPPED - People who have physical or mental impairments that substantially limit one or more major life activities. In the context of transportation, the term usually refers to people for whom the use of conventional transit facilities would be impossible or would create a hardship. These people are also known as transportation handicapped or as people who have a public transportation disability.

HAZARD ANALYSIS - An analysis performed to identify hazardous conditions for the purpose of their elimination or control.

HAZARD - Any real or potential condition that can cause injury or death, or damage to or loss of equipment or property.

HAZARD CRITICALITY - The minimum hazard risk or index value which can be accepted for a given potential hazardous situation. )

HAZARD INDEX - A quantitative measure, combining the numeric probability of occurrence with the hazard severity.

HAZARD LEVEL - A qualitative measure of hazards stated in relative terms.

A. Category I: Catastrophic - will cause death or system loss. B. Category II. , Critical - will cause severe injury, severe occupational illness, or major system damage. C. Category III: Marginal - minor injury, minor occupational illness, or minor system damage. D. Category IV-. Negligible - Less than minor injury, occupational illness, or system damage.

HAZARD PRIORITY - The relative importance assigned to correct an unacceptable hazardous condition.

HAZARD RISK - A qualitative measure of the relative likelihood of occurrence combined with the hazard level.

HAZARD SEVERITY - A quantitative measure of hazard magnitude, expressed in suitable units of measurement.

HAZARD ANALYSIS - A systematic analysis of a system operation performed to identify hazards and make recommendations for their elimination or control during all life-cycle phases.

HAZARD PROBABILITY (MIL-STD 882B) - The probability that a hazard will occur during the planned life expectancy of a system, expressed in potential occurrences per unit of time, events, population, items, or activity.

HEAD END The beginning or forward portion of any train.

HEAD SIGN - A sign indicating the destination of the transit unit (vehicle or train), usually located above the windshield.

HEADWAY MANAGEMENT - A technique for managing the operation of transit units (vehicles or trains) that focuses on maintaining a certain spacing between units on the same line, instead of on adhering to a timetable. For example, if units become bunched, corrective measures might include delaying the units at the rear of the bunch to provide regular headways and hence load distribution, even at the expense of reducing timetable adherence.

HEADWAY -The time interval between the passing of the front ends of successive transit units (vehicles or trains) moving along the same lane or track (or other guideway) in the same direction, usually expressed in minutes; see also SERVICE FREQUENCY.

HEADWAY CONTROL - The means by which the desired headway is maintained.

HIGHWAY -

Arterial - a general term denoting a major highway used primarily by through traffic, usually on a continuous route.

HOLDING LIGHTS - Indicators at wayside stations which, in conjunction with manual or automatic train dispatchers, are used to maintain scheduled train operation.

HOME SIGNAL - A fixed signal at the entrance of a route or block to govern trains entering that route or block.

HSGT - High-Speed Ground Transportation; see transportation system, high-speed ground.

HUB MILES (hub kilometers) -Actual logged miles (kilometers) of vehicle operation, usually read from a hubometer or odometer.

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I

IMPEDANCE - 1. In transportation generally, any condition that restricts or discourages travel, or a measure of that condition. 2. In transportation modeling, any such condition explicitly accounted for within the model. Time and costs are the factors usually considered, but others may also be examined.

IMPEDANCE, BALLAST - The impedance shunting a track circuit due to the condition of the ballast.

IMPEDANCE BOND (See BOND, IMPEDANCE) - An iron core coil of low resistance and relatively high reactance, used to provide a continuous path for the return propulsion current around insulated joints and to confine the alternating current signaling energy to its own track circuit.

IMPEDANCE MATRIX -in planning, an array of zone-to-zone trip impedances, such as travel times and travel costs.

IMPEDANCE, SHUNT - Impedance between rails presented by a train's wheels and axles and the wheel/rail interface.

IN KIND - 1. The intrinsic value of goods and services (work time, supplies, etc. ) used to provide the required local participation for federal and state grants. 2. State or local funds required by the federal government to complement federal funds for a project; also known as match or matching funds. A match may also be required by states in funding projects that are a joint state and local effort.

IN ADVANCE OF A SIGNAL - The territory beyond a signal as seen from an approaching train.

IN APPROACH OF A SIGNAL - The territory to which a signal indication is conveyed. (1,9)

INCIDENT - An unforeseen event or occurrence which does not result in injury or property damage; event that results in the delay or annulment of one or more trains.

INCLINED PLANE RAILWAY - A special type of tramway vehicle modified to run on rails so that its passenger seats remain horizontal while its undercarriage is angled parallel to the slope. It is used for steep gradients.

INDEPENDENT AUDIT - An audit by an organizational group other than that performing the audited work. Can be part of the same company but must retain independent reporting to senior management other than that performing the work. May also be an outside organization.

INDICATION - The information conveyed by the aspect of a signal.

INDICATION LOCKING (See LOCKING, INDICATION) - Electric locking of control circuits which prevents actions that would result in an unsafe condition for a train movement if a signal, switch, or other operative unit fails to make a movement corresponding to a control command.

INDICATION POINT - The point at which the train control or cab signal impulse is transmitted to the rail vehicle apparatus from the track element.

INDICATION, SIGNAL - The information conveyed by the aspect of a signal.

INDICATOR, APPROACH - An indicator used to indicate the approach of a train.

INDICATOR, AUDIBLE - (See SIGNAL, Audible) - A sound-producing device used for attracting attention.

INDICATOR, CAB (See SIGNAL, CAB) - A signal in the train operator's cab which conveys the automatic block aspects and indicates the prevailing speed command.

INDICATOR, SPEED - An analog or digital speedometer mounted in cab.

INDICATOR, SWITCH (POSITION) - An indicator used to indicate the position of switch points.

INDUCTION LOOP SENSOR - A loop of wire (inductor) embedded in the roadbed that carries a small electric current used to sense a passing vehicle and to yield information about the presence and velocity of the vehicle. Induction loops are also used to actuate traffic signals.

INDUCTIVE TRAIN CONTROL SYSTEM - see control system, continuous train.

INDUCTIVE ANALYSIS - An analysis which determines the impact of specific events or failures on a system (A bottom-up approach. "What happens if a specific event or failure occurs?").

INDUCTOR - A track element consisting of a mass of iron, with or without a winding, that stimulates the train control, train stop, or cab signal mechanisms on the rail vehicle.

INFRASTRUCTURE - 1. In transit systems, all the fixed components of the transit system, such as rights-of-way, tracks, signal equipment, stations, park-and-ride lots, bus stops, maintenance facilities. 2. In transportation planning, all the relevant elements of the environment in which a transportation system operates.

INSPECTION PLATE - The portion of the farebox on which coins and tickets land so that they may be seen by the operator.

INSPECTOR (road supervisor, route supervisor, street supervisor) - a transit employee who evaluates performance, enforces safety and work rules, and attempts to solve problems; an inspector may be mobile (covering several districts in a radio-equipped vehicle) or fixed (assigned to a post at a designated intersection).

INSULATED RAIL JOINT (See JOINT, RAIL; INSULATED) - A rail joint in which electrical insulation is provided between adjoining rails.

INTEGRAL STRUCTURE (integral vehicle construction) - A vehicle in which the frame and body are built as one unit, so that all principal members are load bearing, as distinguished from body-on-chassis.

INTEGRATED TEST - Those tests performed to demonstrate that a system or systems function satisfactorily when connected to interfacing systems.

INTEGRATION/TEST/CHECKOUT PHASE - The phase of the life cycle which begins when the equipment is installed, extending through system checkout, and ends when the system begins revenue operation.

INTERCHANGE - 1. The system of interconnecting ramps between two or more intersecting travel ways (highways, transit guideways, etc. ) that are grade separated. 2. The transfer of rail cars from one railroad or transit agency to another so that they may be used by someone other than the owner.

INTERFACE HAZARD ANALYSIS - An analysis performed on a system to identify, classify, and eliminate hazards. It identifies safety problem areas of an entire system and assesses total system risk by examining the interfaces of the subsystems. (Also see SYSTEM HAZARD ANALYSIS)

INTERFACE - The junction points or the points within or between systems or subsystems where matching or accommodation must be properly achieved in order to make their operation compatible with the successful operation of all other functional entities.

INTERLINE - In public passenger transportation, a term denoting the interchange of passengers between one or more bus lines, rail transit lines, or railroads.

INTERLOCKED SWITCH (See SWITCH, INTERLOCKED) - A track switch within interlocking limits, the control of which is interlocked with other functions of the interlocking.

INTERLOCKING - In rail systems, an arrangement of switch, lock, and signal devices that is located where rail tracks cross, join, separate, and so on. The devices are interconnected in such a way that their movements must succeed each other in a predetermined order, thereby preventing opposing or conflicting train movements.

INTERLOCKING LIMITS - The track length between the most remote opposing home signals of an interlocking.

INTERLOCKING, AUTOMATIC - An interlocking controlled by circuit logic so that movements succeed each other in proper sequence without need for manual control.

INTERLOCKING, MANUAL - An interlocking operated manually from an interlocking machine, so interconnected by means of mechanical or electric locking that movements must succeed each other in proper sequence.

INTERLOCKING RELAY - A relay having two independent magnetic circuits with their respective armature so arranged that the dropping away of either armature prevents the other armature from dropping away to its full stroke.

INTERLOCKING, RELAY TYPE - An interlocking in which locking is accomplished electrically by interconnection of relay circuits.

INTERLOCKING SIGNAL (See SIGNAL, INTERLOCKING) - A wayside signal which governs movements into or within interlocking limits.

INTERLOCKING STATION - A place from which an interlocking is operated.

INTERMODAL - Between or including more than one means or mode of transportation. Service coordination between two or more different transportation modes. This arrangement may include joint (transfer) stations, coordinated scheduling, joint fares and combined public information activities.

INTERSECTION - The point at which two or more roadways meet or cross.

Point of-see POINT OF INTERSECTION.

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J

JERK - Time rate of change of acceleration or deceleration of a vehicle, measured in feet per second cubed (meters per second cubed).

JOHSC - Joint Occupational Health and Safety Committee

JOINT-USE CORRIDOR -A transportation right-of-way used for more than one mode of transportation, such as trains and automobiles; see also AREA, Multiple-use.

JOINT DEVELOPMENT joint-use development) - 1. In transportation, ventures undertaken by the public and private sectors for development of land above, below, or along transportation facilities. 2. Coordinated development of an area by the public sector and private enterprise.

JOINT OPERATIONS - 1. Rail operations conducted on a track used jointly or in common by two or more rail companies. 2. Operation of a train, locomotive, car, or other on-track equipment by one railroad over the track of another railroad.

JOINT, RAIL; INSULATED (See INSULATED JOINT RAIL) - A rail joint in which electrical insulation is provided between adjoining rails.

JUMPER CABLE (Jumper) - A flexible conductor or group of conductors arranged to connect electric circuits between adjacent vehicles or rails.

JUNCTION - 1. In transit operations, a location at which transit routes or lines converge or diverge. 2. In traffic engineering, an intersection.

JUNCTION POINT - 1. A location at which a rail branch line track connects with a main-line track. 2. A location at which two or more railroads interchange cars over connecting tracks. 3. A location at which several transit lines converge.

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K

K FACTOR - 1. In a gravity or similar model, a travel constant that reflects intangible values and perceptions of the user, for example, modal image, friendly service. 2. In vehicle operations, the ratio of the minimum operating separation between two vehicles to the maximum emergency stopping distance. Normally, the factor is greater than 1 to provide a margin of safety.

KEY-BY -The act of lowering a trip stop in order to pass a signal displaying a stop indication. (So called because of the use of the operator's key to actuate the mechanism for lowering the trip stop).

KIOSK - An octagonal structure located at each entrance to a station which serves as the hub of communications for the station.

KISS AND RIDE (kiss 'n' ride, K&R) - An access mode to transit whereby passengers (usually commuters) are driven to a transit stop and left to board a transit unit and then met after their return trip. Transit stations usually provide a designated area for dropping off and picking up such passengers.

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L

LAP - The position of a brake valve in which the pressure being controlled is being neither increased nor decreased.

LATERAL MOTION - In rail operation, motion crosswise of the path of travel that results from the flexibility that must be provided in the track structure to permit its negotiation. It is experienced by all rail car parts except the wheels and axles. Lateral motion may also occur when the wheel tread is worn to a dished profile. This type of wear causes truck hunting at speed and hence produces lateral motion.

LAY-BY - 1. In rail systems, a side track. 2. In bus systems, see BUS BAY.

LAYOVER ZONE - A designated stopover location for a transit vehicle at or near the end of the route or line or at a turn-back point.

LAY-UP (STORAGE) - The act of storing cars of a train.

LEVEL OF SERVICE (LOS) - 1. A set of characteristics that indicate the quality and quantity of transportation service provided, including characteristics that are quantifiable (system performance, e.g., frequency, travel time, travel cost, number of transfers, safety) and those that are difficult to quantify (service quality, e.g., availability, comfort, convenience, modal image). 2. For highway systems, a qualitative rating of the effectiveness of a highway or highway facility in serving traffic, in terms of operating conditions. The Highway Capacity Manual identifies operating conditions ranging from A, for best operation (low volume, high speed), to F, for worst conditions. 3. For para-transit, a variety of measures meant to denote the quality of service provided, generally in terms of total travel time or a specific component of total travel time. 4. For pedestrians, sets of area occupancy classifications to connect the design of pedestrian facilities with levels of service (A for best through F for worst). 5. For transit rights-of-way, see RIG HT-OF-WAY.

LIFE CYCLE - The acquisition and operations phases of a system's evolution. The phases of development of a system typically include the concept, design, development, production and deployment, and disposition efforts.

LIMITS, INTERLOCKING - The tracks between the most remote opposing home signals of an interlocking.

LINE - 1. A transportation company (e.g., a bus line). 2. A transit service operated over a specified rout or combination of routes. 3. An active (in-use) railroad track or AGT guideway. 4. In network coding, a route and its service level, including mode designation (type of service), line number, headway, and sequence of transfer points (nodes). These factors describe the lines route as an ordered set.

Double-track main - a rail main line that has two tracks, usually one for each direction.

Single-track main - a rail main line that has one track. It requires passing sidings for bi-directional operation.

LINE MILES (line kilometers, miles or kilometers of directional roadway) The sum of the actual physical length (measured in only one direction) of all streets, highways, or rights-of-way traversed by a transportation system (including exclusive rights-of-way and specially controlled facilities), regardless of the number of routes or vehicles that pass over any of the sections; see also ROUTE MILES.

LINEAR INDUCTION MOTOR - See MOTOR, Linear induction, Liner synchronous motor-see motor, linear synchronous.

LOAD FACTOR - 1. The ratio of used capacity to offered capacity of equipment or a facility during a specified time period. It is usually expressed as a percentage of seats occupied at a given point or (in continuous form) passenger miles (kilometers) divided by seat miles (kilometers). For rail services, the load factor is sometimes expressed as passenger miles (kilometers) per train mile (kilometer) to account for the ability to couple rail cars together to achieve efficiency. 2. The ratio of passengers actually carried versus the total passenger capacity of a vehicle; also known as a utilization coefficient.

LOAD SHEDDING - Reducing the amount of conventional transit service at peak hours by encouraging the use of para-transit operations to carry some of the peak-period passengers.

LOCKING - In rail systems, the electrical or mechanical establishment of a condition for a switch, interlocking route, speed limit, or automatic function that cannot be altered except by a prescribed and inviolate sequence of unlocking actions.

LOCKING, APPROACH - Electric locking effective while a train is approaching within a specified distance, a signal displaying an aspect to proceed and which prevents until after the expiration of a predetermined time interval after such signal has been caused to display its most restrictive aspect, the movement of any interlocked or electrically locked switch, movable point frog, or derail in the route governed by the signal and which prevents an aspect to proceed from being displayed for any conflicting route.

LOCKING, DETECTOR (OCCUPANCY) - A method of locking which prevents the movement of a track switch while the track circuit or circuits surrounding that switch is occupied by a train.

LOCKING, ELECTRIC - The combination of electric locks and controlling circuits by means of which levers of an interlocking machine, switches, or other units operated in connection with signaling and interlocking, are secured against operation under certain conditions.

LOCKING, INDICATION - Electric locking which prevents actions that would result in an unsafe condition for a train movement if a signal, switch, or other operative unit fails to make a movement corresponding to that of its control.

LOCKING, MOVABLE BRIDGE - The rail locks, bridge locks, bolt locks, circuit controllers, and electric locks used in providing interlocking protection at a movable bridge.

LOCKING, ROUTE - Electrical locking, effective when a train passes a signal displaying an aspect for it to proceed, which prevents the movement of any switch, movable point frog, or derail in that route in advance of the train within the route cleared.

LOCKING, TIME - Interlocking protection which prevents the position of a switch, movable point frog, or derail from being changed, until a predetermined time has elapsed after a signal governing movements over the device has been restored to "STOP" before being passed by a train for which it was "cleared. "

LOCKING, TRAFFIC - Electric locking which prevents the actuation of devices for changing the direction of traffic on a section of track while that section is occupied or while the signal displays an aspect for a movement to proceed into that section.

LOCKING, TRAILING RELEASE OF - Locking so arranged that as a train clears a track section of the route, the locking affecting that section is released.

LOCOMOTIVE - A self propelled unit of equipment designed for moving other equipment and includes a self-propelled unit designed to carry freight and/or passenger traffic. For rapid transit and commuter reporting, any powered unit, including a married pair, will be identified as a locomotive.

Self-propelled - a locomotive that requires no external source of electric power for its operations.

LOOP - 1. A transit route or guideway layout that is of a closed continuous form, such as a circle. 2. A terminal track layout or bus driveway that reverses the direction of a vehicle without the vehicle's reversing.

LOW RAIL - (See RAIL, Low.)

LRRT - Light Rail Rapid Transit - (See TRANSIT SYSTEM, Light rail rapid.)

LRT - Light Rail Transit - (See TRANSIT SYSTEM, Light rail.)

LRV - Light Rail Vehicle-, (See CAR, Light rail.)

LSM - Linear Synchronous Motor - (See MOTOR, Linear synchronous.)

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M

MA - Motor Alternator

MACHINE, INTERLOCKING - An assemblage of manually operated levers or equivalent devices for the control of signals, switches, or other units, including mechanical or electric locking or both, to establish proper sequence of movements.

MAGNETIC FARECARD - A card containing a magnetic tape strip or other electronic means of indicating the value purchased. The card is usually obtained from a vending machine and must be inserted into a farecard reader to gain access to the paid area of the transit system. In some systems, the card must also be inserted into a farecard reader to exit the paid area.

MAGNETIC LEVITATION (MAGLEV) - Support technology that keeps a vehicle vertically separated from its track or riding surface by magnetic force, either attractive or repulsive.

MAINLINE - Track over which passenger service is operated.

MAIN TRACK - A designated track upon which trains are operated by timetable, train order or both, or the use of which is governed by block signals.

MAINTAINABILITY - A characteristic of design and installation which is expressed as the probability that an item will be restored to a specified condition in a given period of time, when maintenance is performed in accordance with prescribed procedures and resources.

MAINTENANCE - The upkeep of vehicles, plant, machinery, and equipment. It may be scheduled, planned, progressive, or periodic on the basis of preestablished intervals of time, hours, or mileage, and employ preprinted checklists (preventive maintenance), or it may be unscheduled or corrective, in which case it is generally not interval based.

MAINTENANCE, CORRECTIVE - The action taken to restore a failed item of equipment to an operable state.

MAINTENANCE, PREVENTIVE - The actions performed in an attempt to retain an item in a specified condition by providing systematic inspection, detection and prevention of incipient failure.

MAINTENANCE, SCHEDULED - Programmed preventive maintenance.

MAINTENANCE, UNSCHEDULED - Maintenance action (unscheduled maintenance) initiated by the malfunction of equipment.

MALFUNCTION - Any anomaly wherein a system, subsystem, or component fails to function as intended.

MANUAL BLOCK SIGNAL SYSTEM - A block signal system wherein the use of each block is governed by block signals controlled manually, or by block limit signals, or both, upon information by telephone, radio, or other means of communication.

MANUAL TRAIN CONTROL - An operating mode in which the train responds to the actions of its operator through manipulation of the brake valve or master controller.

MARGINAL - A hazard severity category defined as "Category III, Marginal". Category III is defined as failure conditions which could result in minor injury, minor occupational illness, or minor system damage. ( See HAZARD SEVERITY)

MARKER - A front or rear signal of a train (flag, reflector, or lamp).

MASS TRANSIT - (See PUBLIC TRANSIT.)

MASTER CONTROLLER (See CONTROLLER, MASTER) - The device which generates local and train lined signals to the vehicle control system.

MAXIMUM LOAD POINT (MLP) - The point on a transit line or route at which the passenger volume is the greatest. There is one maximum load point in each direction.

MAXIMUM LOAD SECTION (MLS) - The section of a transit line or route that carries the highest total number of passengers for that line or route and direction.

MAXIMUM AUTHORIZED SPEED (See SPEED, MAXIMUM AUTHORIZED) - The highest speed limit which is authorized for a particular section of track.

MEAN CYCLES BETWEEN FAILURES (MCBF) - The arithmetic mean of the number of cycles between successive failures of a repairable device.

MEAN DISTANCE BETWEEN FAILURES (MDBF) - The arithmetic mean of the distance traveled between successive failures of a repairable vehicle.

MEAN DOWN TIME (MDT) - The arithmetic mean of the time that the device remains in an inoperable state after it has failed.

MEAN LIFE - The arithmetic mean of time to wear out of all items in the test sample or population.

MEAN MAINTENANCE TIME - The arithmetic mean of the time required to perform a maintenance action.

MEAN TIME BETWEEN FAILURES (MTBF) - The arithmetic mean of the time between successive independent failures, which is the mean equipment operating time per independent failure. The MTBF is the reciprocal of the failure rate.

MEAN TIME BETWEEN HAZARDOUS EVENTS (MTBHE) - The arithmetic mean of the time between successive independent hazardous events.

MEAN TIME BETWEEN SERVICE FAILURES (MTBSF) - The arithmetic mean of the time between failures which interrupt or impact service operations, which is the mean revenue service time per service failure. The MTBSF is the reciprocal of the service failure rate.

MEAN TIME BETWEEN THE EXECUTION OF UNSAFE ERRORS (MTBUE) - The arithmetic mean of the time between software errors that produce an unsafe effect.

MEAN TIME BETWEEN UNSAFE FAILURES (MTBUF) - The arithmetic mean of the time between hardware failures, the occurrence of which have an adverse effect on the safe implementation of a vital UNSAFE function.

MEDICAL TREATMENT - Treatment administered by a physician or by registered professional personnel under the standing orders of a physician. Medical treatment does not include first aid treatment (one-time treatment), precautionary measures such as tetanus shots, and subsequent observation of minor scratches, cuts, bruises or splinters which do not require medical care, even though these services are performed by a physician or registered professional personnel.

MERGE POINT - The section of a guideway or roadway at which two lines or lanes converge to become one.

MINIMUM PATH - The route of travel between two points that has the least accumulation of time, distance, or other impedance measure.

MINIMUM SPEED - A speed not exceeding 30 miles per hour, except in ASC territory train will be governed by speed displayed on cab signal indicator not to exceed 30 miles per hour.

MISHAP - An unplanned event or series of events that result in death, injury, occupational illness, or damage to or loss of equipment or property. (See also ACCIDENT)

MIXED TRAFFIC OPERATIONS - The operation of transit vehicles on nonexclusive rights-of-way (transit ROW category C) with non-transit vehicles.

MODAL SPLIT (mode split) - 1. The proportion of total person trips that uses each of various specified modes of transportation. 2. The process of separating total person trips into the modes of travel used; see also URBAN TRANSPORTATION MODELING SYSTEM and MODEL, Sequential. 3. A term that describes how many people use alternative forms of transportation. It is frequently used to describe the percentage of people who use private automobiles, as opposed to the percentage who use public transportation.

MODE - A particular form of travel, for example, walking, traveling by automobile, traveling by bus, traveling by train.

MODE 1 (AUTOMATIC) [RAIL] - Train operation with train under ATO control with ATP monitoring and protection.

MODE 2 (MANUAL) [RAIL] - Train operation with train under manual (Train Operator) control with operation monitored and protected by the ATP System.

MODE 3 (MANUAL WITH ATP CUTOUT) [RAIL] - Train operation under manual (Train Operator) control without ATP monitoring and protection. This mode is not permitted unless passengers are evacuated from train and an Absolute Block is established to allow train movement.

MODE, AUTOMATIC TRAIN OPERATION - (See AUTOMATIC TRAIN OPERATION) - That subsystem within the automatic train control system which performs any or all of the functions of speed regulation, programmed stopping, door control, performance level regulation and other functions normally assigned to the train operator.

MODE, CAB SIGNAL - A form of manual train control wherein the operator controls the speed of the vehicle in accordance with signal aspects displayed on the cab signal indicator.

MODE, MANUAL (See MANUAL TRAIN CONTROL) - An operating mode in which the train responds to the actions of its operator through manipulation of the brake valve or master controller.

MODE, WAYSIDE SIGNAL - A form of manual train control wherein the operator controls the speed of the vehicle in accordance with the indications given by wayside signals.

MODEL - 1. A mathematical or conceptual presentation of relationships and actions within a system. It is used for analysis of the system or its evaluation under various conditions; examples include land use, economic, socioeconomic, transportation. 2. A mathematical description of a real-life situation that uses data on past and present conditions to make a projection about the future.

Fratar (Fratar distribution) - a method of extrapolating a given distribution of trips on the basis of growth factors for the origin and destination ends. It is named after Thomas J. Fratar, the developer.

Multiple-choice - a model that relaxes the assumption of only two possible choices and allows any number of possible choices within a given level of travel choice, such as mode, route, or time period, or among any or all of these trip characteristics.

Sequential - a demand model that is based on the assumption that travel decisions are made in a sequence of steps, such as whether or how often to travel (trip generation), what destination to choose (trip distribution), which mode to choose (modal split), and which route to choose (trip assignment).

MONITORING - An informal activity used by system safety and safety certification staff to view an activity or process. It is informal, of short-term duration, and normally does not require a formal report.

MONOBEAM - A type of guideway that consists of a single beam, usually elevated. It generally has a rectangular cross section that is usually straddled by the associated vehicles.

MOTOR (electric motor) - A machine that transforms electrical energy into mechanical energy (torque).

Direct Current - an electric motor (shunt, compound, etc.) That operates on direct current.

Double-sided linear induction (DLM, DSLM) - a linear induction motor that has its active primary winding constructed so that it reacts magnetically with both sides of the guideway-mounted reaction rail (secondary winding).

Induction - an asynchronous alternating-current motor that converts alternating-current electric power, delivered to the primary winding (usually the stator) and carried as induced current by the secondary winding (usually the rotor), into mechanical power; see also MOTOR, Linear induction.

Linear Induction (LIM) - an asynchronous linear alternating-current motor composed of a winding in the guideway and a winding in the vehicle, one of which is energized to produce opposing magnetic fields that propel by alternately attracting and repelling the vehicle; see also MOTOR, Double-sided linear induction, and MOTOR, Single-sided linear induction.

Linear synchronous (LSM, synchronized linear motor) - a synchronous linear alternating-current motor that supplies fixed speed operation for the powered vehicle. The fixed speed can be controlled electronically.

Series-wound - A motor in which the field circuit is connected in series with the armature circuit. It is also often called a traction motor.

Single-sided linear induction (SLM, SSLM) - a linear induction motor that has a single primary winding on one side of the secondary or reaction rail.

Shunt - a type of rotary electric motor in which the field coils are connected in parallel with the motor armature.

Traction - an electric motor, usually direct current and series wound, that propels a vehicle by exerting its torque through the wheels; see also MOTOR, Series-wound.

MOTORMAN (See OPERATOR) - That person having direct and immediate control of the movement of a train.

MOVEMENT, FACING - The movement of a train over the points of a switch which face in a direction opposite to that in which the train is moving.

MOVEMENT, TRAILING - The movement of a train over the points of a switch which face in a direction in which the train is moving.

MOVING WALKWAY (MOVING SIDEWALK, PASSENGER OR PEDESTRIAN CONVEYOR, PASSENGER BELT) - A fixed conveyor device (usually a flexible belt) on which pedestrians may stand or walk while being transported; see also RAMP, MOVING.

MSDS - Material Safety Data Sheet

MU - Multiple Unit - (See CAR, Multiple-unit.)

MULTI MODAL - Concerning or involving more than one transportation mode.

MULTIPLE-UNIT CONTROL SYSTEM - (See CONTROL SYSTEM, Multiple-unit.

MULTIPLE UNIT (MU) (OPERATION, CONTROL) - A method of controlling the actions of the propulsion, braking, and other systems of two or more cars of the train from a single cab.

MULTIPLE UNIT EQUIPMENT - Equipment capable of being propelled by the use of electrical energy conducted by third rail contact shoes.

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N

NAME, SIGNAL - The term used to describe the signal aspect.

NARROW GAUGE - See gauge, narrow.

NEAR-SIDE STOP - See stop, near-side.

NEGLIGIBLE - A hazard severity category defined as "Category IV, Negligible", Category IV is defined as failure conditions which cause less than minor injuries, illness, or system damage.

NETWORK - 1. In planning, a system of links and nodes that describes a transportation system. 2. In highway engineering, the configuration of highways that constitutes the total system. 3. In transit operations, a system of transit lines or routes, usually designed for coordinated operation.

Composite-in planning, a group of interconnected lines that represents a multi modal combination of existing and proposed transportation facilities and routes. It is often used for simulating travel patterns and determining capacities or other transportation system characteristics. Grid-1. In planning, an imaginary network of evenly spaced horizontal and vertical bars or lines that divides a study area into small geographic zones.

NETWORK CODING - The process of abstracting details of a real transportation network and recording them in a form suitable for computer processing.

NO-ACTION ALTERNATIVE (do-nothing alternative, null alternative) - A planning option of leaving the situation as it already exists. Existing facilities and services are maintained, and existing transportation policies are continued. See also TRANSPORTATION SYSTEM MANAGEMENT ALTERNATIVE.

NODE - In planning, a point that represents an intersection of two or more links, highways, or transit lines or routes or a zone centroid; used in trip assignment.

NOISE, ELECTRICAL - Interference produced by undesirable or casual electrical occurrences.

NORMAL DIRECTION (See DIRECTION, Normal) - The designed predominant direction of train movement as specified by the rules.

NORMAL POSITION (See POSITION, Normal) - The position in which a switch is aligned for train movement continuing on the same track.

OPEN LOOP - No feedback control.

NOSING - A transverse, horizontal motion of a locomotive that exerts a lateral force on the supporting structure.

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O

OCCUPATIONAL INJURY - Any injury such as a cut, fracture, sprain, amputation, etc. , which results from a work accident or from an exposure involving a single incident in the work environment. The date of recordability for occupational injuries is the date on which the work accident or single incident exposure occurred.

OFF-LINE - Not in the main flow of traffic or not on the main line of traffic, for example, off-line station.

OFF PEAK - The periods of time outside the peak periods; see also BASE PERIOD.

OFFSET - 1. In transit operations, the amount of time (system- wide) that the train control computer has added into the theoretical schedule to maintain proper train sequencing, scheduled connections, and headways. 2. In traffic operations, the time difference between traffic signals as measured from some reference point.

OHSA - Occupational Health and Safety Act

ON-TIME PERFORMANCE - The proportion of the time that a transit system adheres to its published schedule times within stated tolerances; for example, a transit unit (vehicle or train) arriving, passing, or leaving a predetermined point (time point) along its route or line within a time period that is no more than x minutes earlier and no more than y minutes later than a published schedule time. (Values of 0 minutes for x and 5 minutes for y are the most common. )

ONE-ZONE RIDE - A transit ride within the limits of one fare zone.

OPERATING EMPLOYEE - The employee of a transit system having direct and supervisory responsibility for the movement of trains.

OPERATING HAZARD ANALYSIS (OHA) - Identifies and evaluates hazards resulting from the implementation of operations or tasks performed by persons, considering: operation, test, maintenance, repair transportation, handling, emplacement or removal of the system.

OPERATING RATIO - The ratio of operating expenses to operating revenue; the inverse of cost recovery ratio. It is used as a measure of financial efficiency. See also FARE RECOVERY RATIO.

OPERATING TIME - The time period between turn-on and turn-off of a system, subsystem, component or part during which time operation is as specified. Total operating time is the summation of all operating time periods.

OPERATIONAL SYSTEM - In system development, a system that is now available for use.

OPERATIONAL PHASE -The post construction phase where designed project function is achieved and maintenance requirements begin.

OPERATIONS CONTROL CENTER (OCC) [RAIL] - The place where train control and train supervision is accomplished for the entire transit system.

OPERATOR - 1. An employee of a transit system whose workday is spent in the operation of a transit unit (vehicle or train); examples include bus driver, gripman, motorman, rapid transit train motor operator. Such an employee may also be known as a plat form operator. 2. The organization that runs a transportation system on a day-to-day basis and is also known as an operation, property, or system, see also PROPERTY.

ORGANIZATIONS - See also U.S. GOVERNMENT and UNION, Transit

Association of American Railroads (AAR) - an industry association made up of individual railroads in the United States, Canada, and Mexico. It performs a variety of technical services for the railroads, and its purposes include the promotion of railroad interests and the standardization and coordination of operating and mechanical activities within the railroad industry.

OVERHEAD CONTACT SHOE (contact shoe, trolley shoe) - A metal bar for collecting current from an overhead conductor along which it slides. It is held in place by a pantograph or bow.

OVERSPEED CONTROL - That portion of the carborne automatic train control system which, in a fail-safe manner, enforces speed limits.

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P

PA - Public Address

PADDLE BOARD (paddle, run card, run guide, train card) - The headway sheets (time schedule) made up for each run (operator's piece of work) that list all the pieces of work on that run (including any special notations) for the operator.

PANTOGRAPH - A device for collecting current from an over- head conductor, characterized by a hinged vertical arm operated by springs or compressed air and a wide, horizontal contact surface that glides along the wire. Older versions usually consist of two parallel, hinged, double-diamond frames.

PANTOGRAPH GATES - Gates located outside and at the end of transit cars so that when cars are coupled, their gates meet to prevent people from falling into the area between the cars.

PARA-TRANSIT - Forms of transportation services that are more flexible and personalized than conventional fixed route, fixed schedule service but not including such exclusive services as charter bus trips. The vehicles are usually low-or medium-capacity highway vehicles, and the service offered is adjustable in various degrees to individual users' desires. Its categories are public, which is available to any user who pass a predetermined fare (e.g., taxi, jitney, dial-a-ride), and semipublic, which is available only to people of a certain group, such as the elderly, employees of a company, or residents of a neighborhood (e.g., vanpools, subscription buses).

PARK AND RIDE (park-n-ride, P&R) - An access mode to transit in which patrons drive private automobiles or ride bicycles to a transit station, stop, or carpool/vanpool waiting area and park the vehicle in the area provided for that purpose (park-and-ride lot, park-and-pool lot, commuter parking lot, bicycle rack or locker). They then ride the transit system or take a car- or vanpool to their destinations.

PARKING -

Fringe (peripheral parking) - a parking facility located immediately outside the central business district, where personal vehicles may be parked and travelers may continue their trip to downtown via transit, carpool, or vanpool.

PARKING FACILITY - An area, which may be enclosed or open, attended or unattended, in which automobiles may be left, with or without payment of a fee, while the occupants of the automobiles are using other facilities or services.

PASSENGER - A person who rides a transportation vehicle, excluding the operator or other crew members of that transportation vehicle; see also TRIP, Passenger; TRIP, Linked; and TRIP, Unlinked. Revenue-a passenger who pays (or has prepaid) a fare. Transfer-a passenger who changes from one route or line to another route or line.

Revenue - a passenger who pays (or has prepaid) a fare.

PASSENGER CONTROLS - A system of railings, booths, turnstiles, and other fixtures for collecting fares and otherwise directing the movement of passengers. The controls may also be used to maintain the distinction between fare-paid and unpaid people.

PASSENGER LOAD - The number of passengers on a transit unit (vehicle or train) at a specified point.

PASSENGER MILE (passenger kilometer) - The transportation of one passenger a distance of I mi (km).

PASSENGER MILES PER TRAIN MILE (passenger kilometers per train kilometer) - The number of passenger miles (kilometers) accomplished by a given train mile kilometer). The measure is the equivalent of load factor for buses, boats, or aircraft, but it also adjusts for distortions introduced as cars are added to trains. As an example, 1 00 people in one rail car of 1 00-passenger capacity is a load factor of 1 00 percent. If a car is added for 1 0 more passengers, the load factor drops to 55 percent-yet in many ways, productivity has gone up, not down.

PASSENGER STATION - A place at which trains are scheduled to receive and/or discharge passengers.

PASSENGER TRAIN - A train carrying revenue passengers.

PAY -

Spread time premium (spread penalty, spread premium time) - 1. Extra compensation paid for work perform in excess of a specified spread time, for example, 10 hours. 2. In some systems, extra compensation paid to certain employees whose duties require work during the morning and evening peak hours, with non-working release time in between. This premium pay is to compensate for the inconvenience of working a split shift.

PCE - Passenger Car Equivalence.

PEAK (peak period, rush hours) - 1. The period during which the maximum amount of travel occurs. It may be specified as the morning (a.m.) or afternoon or evening (p.m.) peak. 2. The period when demand for transportation service is heaviest.

PEAK/BASE RATIO (peak/off-peak ratio) - 1. The ratio between the number of vehicles operating in passenger service during the peak hours and that during the base period. 2. The ratio between the number of passengers carried during the peak hours and that during the base period.

PEDESTRIAN SIGNAL-ACTUATING DEVICE - A device to actuate traffic signals that is designed to be used by pedestrians.

PEOPLE MOVER - An automated transportation system (e.g., continuous belt system or automated guideway transit) that provides short-haul collection and distribution service, usually in a major activity center.

Downtown (DPM) - a people mover that primarily serves internal movements in a central business district.

PERFORMANCE AUDIT - In transit operations, an evaluation of a transit system's efficiency and effectiveness; a management review focusing on system's goals, objectives, and performance. A performance audit is also used to determine whether the transit agency is complying with local, state, and federal regulations on such matters as highway safety, pollution control, handicapped accessibility, and achievement of revenue-to-cost ratios.

PERFORMANCE INDICATOR (measure of effectiveness) - A quantitative measure of how well an activity, task, or function is being performed. In transportation systems, it is usually computed by relating a measure of service output or use to a measure of service input or cost.

PERFORMANCE LEVEL (TRAIN) - A command, generally instituted by line supervision, which will vary train speed or running time from normal to achieve the desired schedule speed or headway.

PERSONNEL, OPERATING - Those employees of a transit system having direct and supervisory responsibility for the movement of trains, embodying both on-board and wayside duties.

PHA - Preliminary Hazard Analysis

PHANTOM SIGNAL - An aspect displayed by light signal different from the aspect intended, caused by a light from an external source being reflected by the optical system of the signal.

PICKUP - The electrical value which, when applied to a two-state circuit or device, will cause the moving member of the device to move to the position that will just close the front contacts or visually indicated energized position, or will just cause the circuit to change its state.

PILOT - 1. In rail operations, a qualified person assigned to assist train crews who are operating over unfamiliar trackage or operating unfamiliar equipment. 2. On rail vehicles, a wheel guard that protects the front truck of a rail vehicle from foreign objects on the track; also known as a cowcatcher.

PLATFORM (passenger platform) - That portion of a transit facility directly adjacent to the tracks or roadway at which transit units (vehicles or trains) stop to load and unload passengers. Within stations, it is often called a station platform.

Low - a platform at or near the top of the running surface of the transit unit (vehicle or train), requiring the passenger to use steps to board and alight.

POINT OF CONVERGENCE - The location at which two transit routes meet and then continue on the same alignment.

POINT OF DIVERGENCE - The point at which two transit routes separate after operating over the same alignment.

POINT OF EXTENSION - The point at which one transit route is lengthened from an existing rout.

POINT-TO-POINT DEVIATION - A transit routing pattern in which the vehicle passes through pre-specified points in accordance with a prearranged schedule but is not given a specific route to follow between these points. It may provide door-to-door or curb-to-curb service. See also SERVICE, Point deviation.

POINT DETECTOR (See DETECTOR, POINT) - A circuit controller which is part of a switch operating mechanism and operated by a rod connected to a switch, derail, or movable point frog to indicate that the point is within a specified distance of the stock rail.

POINTS (See SWITCH POINT) - A movable tapered track rail, the point of which is designed to fit against the stock rail.

POSITION, NORMAL - The predetermined position in which a switch is aligned when not in use.

POSITION, DE-ENERGIZED - The position assumed by the moving member of an electromagnetic device when the device is deprived of its operating current.

POSITION, REVERSE - The opposite to normal position.

POWER SYSTEM - The electrical devices and equipment that convert, transmit, and use power to operate a vehicle.

POWER (TRACTION) SYSTEM - The substations, feeder cables, contact rails or wires, switch gear and other equipment interfacing with public utilities or other power generation equipment and providing the electrical power for the movement of the trains and the operation of their auxiliary systems.

PPM - Parts Per Million

PRELIMINARY ENGINEERING (preliminary design) - That portion of the development of a project during which the basic planning objectives are translated into specific, well-defined criteria that can permit the final design process to begin.

PRELIMINARY HAZARD ANALYSIS (PHA) - An analysis performed to obtain an initial risk assessment of a concept or system.

PREVENTIVE MAINTENANCE - (See definition of MAINTENANCE.)

PROBABILITY - 1. The relative frequency with which an event occurs or is likely to occur. 2. In statistics, the relative Z possibility that an event will occur, as expressed by the ratio of the number of actual occurrences to the total number of possible occurrences.

PROBABILITY OF A SOFTWARE ERROR BEING UNSAFE (PEU) - The probability that a software error will have an unsafe effect, i.e., an adverse effect on the implementation of a vital function.

PROBABILITY THAT A FAILURE IS UNSAFE (PFA) - The probability that a failure will have an unsafe effect.

PROCEDURES - Established methods to perform a series of tasks.

PROCEED SIGNAL (See SIGNAL, PROCEED) - A wayside or cab signal displaying any aspect which conveys an indication which permits a train to move.

PROCUREMENT/INSTALLATION PHASE - The phase of the system's life cycle which begins with the fabrication or construction of equipment and facilities and ends with the onset of the integration/test/checkout stage.

PRODUCTIVITY - The ratio of units of transportation output to units of input (consumed resource); for example, vehicle miles (vehicle kilometers) per operator hour, or passenger miles (passenger kilometers) per unit cost of operation.

PROGRAM STOP (See STOP, PROGRAMMED) - A train stop preceded by closed-loop braking such that the train is stopped at a designated point according to a predetermined speed-distance profile.

PROPERTY (operation, operator, system) - In the transit industry, a public transit agency or a private transit company with responsibility for transportation services such as bus, ferry, rail; see also TRANSIT DISTRICT.

PROPULSION SYSTEM - The motors, driving mechanism, controls, and other devices that propel a vehicle.

Duel-power - a propulsion system that is capable of operation from two different types of power sources, for example, an internal combustion engine and electricity.

PROTOTYPE SYSTEM - In system development, a system that has been built to demonstrate its capability to operate in the manner intended-, see also VEHICLE, Prototype.

PRT- Personal Rapid Transit - (See TRANSIT SYSTEM, Personal rapid.)

PUBLIC TRANSIT (mass transit) - Passenger transportation service, usually local in scope, that is available to any person who pays a prescribed fare. It operates on established schedules along designated routes or lines with specific stops and is designed to move relatively large numbers of people at one time. Examples include bus, light rail, rapid transit.

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Q

QUALITY ASSURANCE - The planned and systematic pattern of all actions necessary to provide adequate confidence that the end items will perform satisfactorily in actual operations.

QUALITY CONTROL - The system of collection, analysis, and interpretation of measurements and other data concerning prescribed characteristics of a material, process, or product, for determining the degree of conformance with specified requirements.

QUANTITATIVE - Those inductive or deductive analytical approaches which are oriented toward the use of numbers or symbols used to express a measurable quantity.

QUEUE - 1. A line of waiting vehicles, for example, traffic at a signal, or buses at a park-and-ride facility. 2. A line of waiting people.

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R

RADIO - Controlled engine - (See ENGINE, Radio-controlled.)

RADIUS OF CURVATURE - A rating of the severity of a curve by comparing it to an arc of a circle of stated radius.

RAIL - A rolled steel shape laid in two parallel lines to form a track for carrying vehicles with flanged steel wheels.

Continuous welded (CWR) - a number of standard length rails welded together into a single length of 400 or more ft (122 or more m). It provides a smoother running surface and ride than jointed rail.

Corrugated - a rough condition of alternate ridges and grooves that develops on rail tread in service.

Third (contact rail, power rail) - an electric conductor, located alongside the running rail, from which power is collected by means of a sliding shoe attached to the truck of electric rail cars or locomotives.

Fourth - an electrical conductor that provides ground return or negative return for systems in which the running rails are not used for that purpose.

High (outside rail) - the outer or super-elevated rail of a curved track.

Low (inside rail) - the inner rail of a curve that has at-grade alignment, whereas the opposite or outer rail is elevated.

Restraining - a rail placed parallel to the inside running rail on a curve to restrain the wheel flange and reduce wear on the outside running rail.

Running - a rail that supports and guides the flanged wheels of the rail vehicle.

Standard - a 39-foot (11.89-m) section of rail.

RAIL ANCHOR (anti-creeper) - A track device for ballasted track designed to prevent longitudinal rail movement (creep) caused by factors such as traffic or temperature variations.

RAIL CREEP - Longitudinal rail movement, caused by, for example, traffic or temperature variations.

RAIL JOINT - A fastening designed to unite abutting ends of contiguous rails.

Bonded - a rail joint that uses high-strength adhesives in addition to bolts to hold rails together. The bonded joint may be insulated or non-insulated. On electrified track, it conducts electrical power back to the powerhouse.

Compromise - A rail joint between rails of different height and section, or rails of the same section but of different joint drillings.

Insulated - a rail joint designed to arrest the flow of electric current from rail to rail by means of insulation placed so as to separate the rail ends and other metal parts connecting them.

RAIL TREAD - The top surface of the rail that contacts the wheels of the rail vehicle.

RAIL-HIGHWAY GRADE CROSSING - A location where one or more railroad tracks cross a public highway, road, or street or a private roadway, and includes sidewalks and pathways at or associated with the crossing.

RAIL RAPID TRANSIT SYSTEM - An electrified fixed guideway transportation system, utilizing steel rails, usually operating on an exclusive grade-separated right-of-way for the mass movement of passengers within a city or metropolitan area and consisting of its fixed way, transit car vehicles and other rolling stock, power system, maintenance facilities, and other stationary and movable apparatus and equipment, and its operating practices and personnel.

RAILBUS - A relatively light, diesel-powered, two-axle rail vehicle with a body resembling that of a bus.

RAMP - 1. In highway systems generally, an inclined section of roadway over which traffic passes for the primary purpose of ascending or descending to make connections with other roadways. It can also be an interconnecting roadway of an interchange, or any connection between highway facilities of different elevations that vehicles may use to enter or leave a designated highway. 2. For divided highways specifically, a facility that provides access to the through lanes of freeways and expressways or connects two freeways. 3. In traffic assignment, a link that connects a freeway node and an arterial node.

Moving - an inclined moving walkway.

RAPID RAIL TRANSIT SYSTEM - An electrified fixed guideway transportation system, utilizing steel rails, usually operating on an exclusive grade-separated right-of-way for the mass movement of passengers within a city or metropolitan area and consisting of its fixed way, transit car vehicles and other rolling stock. power system, maintenance facilities, and other stationary and movable apparatus and equipment, and its operating practices and personnel.

RATE, BRAKE - The negative time rate of change of speed of vehicle as produced solely by the action of its braking system, or systems in combination.

RATE, DECELERATION - The net negative time rate of change of speed of a vehicle resulting from the summation of all forces acting upon it.

REACTION TIME - The time used by equipment, operator, or both, that elapses between the moment an action is called for and when the desired result occurs.

RECEIVER, TRACK CIRCUIT - A device on the wayside which receives track signal currents for the purpose of occupancy detection.

RECEIVER, TRAIN CONTROL - A device on a vehicle so placed that it is in position to be influenced inductively or actuated by an automatic train control or cab signal roadway element.

RECORDABLE CASES - Those cases involving an occupational injury or occupational illness, including deaths. Not recordable are first aid cases which involve one-time treatment and subsequent observation of minor scratches, cuts, burns, splinters, etc., which do not ordinarily require medical care, even though such treatment is provided by a physician or registered professional personnel.

REDUCED SPEED - A speed not exceeding 15 miles per hour, at which a train can be stopped short of the next signal, another train, obstruction or switch improperly lined, looking out for broken rail or crossing protection not functioning.

REDUNDANCY - The existence in a system of more than one means of accomplishing a given function.

REGULAR TRAIN - A train authorized by a timetable schedule.

REGULATOR, SPEED - An onboard vehicle subsystem, generally but not necessarily a part of the automatic train operation system, which controls acceleration and braking efforts in order for the vehicle to reach and maintain a desired speed within a desired tolerance.

RELAY - A device that is operative by a variation in the conditions of one electric circuit to effect the operation of other devices in the same or another electric circuit. Commonly, an electromagnetic device to achieve this function.

RELAY, CODE FOLLOWING - A relay which will follow or reproduce a code without distortion within practical limits.

RELAY, VITAL - A relay, meeting certain stringent specifications, so designed that the probability of its failing to return to the prescribed state upon de-energization is so low as to be considered, for all practical purposes, nonexistent.

RELIABILITY, ACHIEVED - The reliability level which has actually been attained at some point in time.

RELIABILITY ASSESSMENT - An analytical determination of numerical reliability of a system or portion thereof without actual demonstration testing. Such assessments usually employ mathematical modeling, use of available test results, and some use of estimated reliability figures.

RELIABILITY BLOCK DIAGRAM - A schematic representation which portrays system operation by showing all possible success paths.

RELIABILITY GOAL - A preset reliability objective determined by consideration of operational needs, state-of-the-art capability, cost, time, etc. The goal can be a minimum acceptable level, an expected program accomplishment or an idealistic target.

RELIABILITY -The characteristic which describes the ability of a component, subsystem, or system to perform its specified function without failure and within prescribed limits, expressed as a probability or mean failure rate.

REPAIR - The maintenance activity which restores a failed item to an operable state.

REROUTE - To divert to a route other than the scheduled route, usually with preplanning and for a longer period than that for a detour.

RESIDUAL HAZARDS - Hazards for which safety or warning devices and special procedures cannot be developed or provided for counteracting the hazard which will be specifically identified to safety and program management. Continuation of effort to eliminate or reduce such hazards will be accomplished throughout the program by maintaining awareness of new safety technology or devices being developed and their application to the residual hazards. Justification for the retention of residual hazards will be documented.

RESIDUAL RISK - The risk associated with significant hazards for which there are no known control measures, no plans to control or incomplete control measures.

RESISTANCE, BALLAST (See IMPEDANCE, BALLAST) - The impedance shunting a track circuit due to the condition of the ballast.

RESISTANCE, TRAIN SHUNT - The actual resistance in ohms from rail to rail through wheels and axles of a vehicle and the wheel/rail interface.

RESOLUTION - Changes that are made in the system or subsystem design, procedures, or activities which eliminate or control the identified hazard to an acceptable level.

RESTORATION OF SERVICE -The resumption of service according to schedule after it has been interrupted or operating off schedule.

RESTORING FEATURE - An arrangement on a power operated switch movement by means of which power is applied to restore the switch movement to full normal or to full reverse position before the driving bar creeps sufficiently to unlock the switch.

RESTRICTED SPEED - Proceeding prepared to stop short of train ahead, switch not properly aligned, broken rail or other obstruction, at a speed established by individual transit systems but not to exceed 20 mph.

RESTRICTION OF WORK OR MOTION - The inability of a railroad employee to perform all normally assigned duties because of injury or occupational illness, and includes the assignment of a railroad employee to another job or to less than full time work at a temporary or permanent job.

REVENUE MILES (revenue kilometers) - Miles (kilometers) operated by vehicles available for passenger service.

REVENUE SEAT MILE (revenue seat kilometer) - The movement of one transit passenger seat over 1 mi (km). In other words, the total number of revenue seat miles (kilometers) for a vehicle is obtained by multiplying the number of revenue seats in the vehicle by the number of revenue miles (kilometers) traveled.

REVENUE VEHICLE MILES (revenue vehicle kilometers, paid miles or kilometers) - The distance in miles (kilometers) that a revenue vehicle is operated while it is available for passenger service.

REVERSE MOVE - The forward movement of a train going against the normal direction of traffic.

REVERSE DIRECTION (See DIRECTION, REVERSE) - Train movement in the direction opposite to the normal direction.

REVERSE RUNNING - The operation of a train in the direction opposite to the normal direction.

RIDE QUALITY - A measure of the comfort level experienced by a passenger in a moving vehicle, including the vibration intensity and frequency, accelerations (longitudinal, transverse, and vertical), jerk, pitch, yaw, and roll.

RIDER - 1. A passenger on any revenue service vehicle; also known as a patron. 2. In government reporting, someone making an unlinked trip. Captive - a person limited by circumstances to use one mode of transportation; see also TRANSIT DEPENDENT and TRANSPORTATION DISADVANTAGED. Captive transit - a person who does not have a private vehicle available or cannot drive (for any reason) and who must use transit to make the desired trip; see also TRANSIT DEPENDENT and TRANSPORTATION DISADVANTAGED. Choice - a person who has at least two modes of travel available and selects one to use.

RIDERSHIP (patronage), - The number of people making one-way trips on a public transportation system in a given time period.

RIGHT-OF-WAY (ROW) - 1. A general term denoting land, property, or interest therein, usually in a strip, acquired for or devoted to transportation purposes. For transit, rights-of- way may be categorized by degree of their separation: A fully controlled without grade crossings, also known as grade separated, exclusive, or private; B-Longitudinally physically separated from other traffic (by curbs, barriers, grade separation, etc.) but with grade crossings; C-surface streets with mixed traffic, although transit may have preferential treatment. 2. The precedence accorded to one vehicle or person over another. 3. The legal right of passage over another person's land.

Exclusive - a lane or other facility that is fully grade separated or access controlled and is used only by a specified mode or specified vehicles at all times.

RIGHT-OF-WAY MILES (right-of-way kilometers, first-track miles or kilometers) - The length of right-of-way occupied by one or more lanes or tracks; see also ROUTE MILES.

RIM - On a rail car wheel, that portion around the outer circumference that forms the edge of the tread. The thickness of the rim is a measure of the amount of wear remaining in the wheel, and when this dimension reaches a given limit, the wheel must be scrapped.

RISK - An expression of possible loss over a specific period of time or number of operational cycles. It may be indicated in terms of hazard severity and probability.

RISK MANAGEMENT - An element of the systems safety management function that evaluates the effects of potential hazards on safety by considering acceptance, control, or elimination of such hazards with respect to expenditure of resources.

RISK MANAGEMENT (SYSTEM SAFETY) - An element of the system safety management function that evaluates the safety effects of potential hazards considering acceptance, control, or elimination of such hazards with respect to expenditure of resources.

ROADBED - 1. In railroad construction, the foundation on which the ballast and track rest. 2. In highway construction, the graded portion of a highway within top and side slopes, prepared as a foundation for the pavement structure and shoulder.

ROLL - Motion about the longitudinal axis of a vehicle.

ROTOR - The rotating member of motors, generators, or motor-type relays.

ROUNDHOUSE - A buildings circular in design, used to house locomotives while they are being serviced or repaired; see also BARN.

ROUTE - 1. The geographical path followed by a vehicle or traveler from start to finish of a given trip. 2. A designated, specified path to which a transit unit (vehicle or train) is assigned. Several routes may traverse a single portion of road or line. 3. In traffic assignments, a continuous group of links that connects two centroids, normally the path that requires the minimum time to traverse. 4. In rail operations, a determined succession of contiguous blocks between two controlled interlocked signals.

ROUTE MILES (route kilometers) - Various definitions exist for this statistic: 1. One-way duplicating is total mileage (kilometers) of routes, where the roadway or guideway segments of each individual route are summed up in one direction. For example, a 1-mi (km) segment over which buses operate in both directions would be reported as 2 mi (km); also known as directional route miles (kilometers) or miles (kilometers) of roadway or route. 2. One-way non-duplicating is total mileage (kilometers) of routes, where a particular roadway or guideway segment is only counted once regardless of number of routes or direction of travel on that segment; also known as line miles (kilometers) or miles (kilometers) of directional roadway. 3. Two-way mileage (kilometers) is total mileage (kilometers) of each route covered from start to finish. No attention is given to direction of routes or number of routes using any particular segment of roadway or guideway.

ROUTE STRUCTURE - 1. A network of transit routes. 2. The pattern of transit routes, for example, grid, radial.

ROUTE, INTERLOCKED; INTERLOCKING - A route within interlocking limits.

ROUTE REQUEST - The registration at an interlocking of a desired interlocked route.

ROUTES, CONFLICTING - Two or more routes, opposing, converging or intersecting, over which movements cannot be made simultaneously without possibility of collision.

ROUTING AND CONTROL ALGORITHM - A numerical technique for assigning trips (usually vehicle trips) to routes and controlling flows of traffic in simulation of transportation networks.

ROW - Right-Of-Way.

RULE - 1. In rail operations, a law or order authoritatively governing conduct or action. 2. A law or order authoritatively governing conduct or action.

RUN - 1. The movement of a transit unit (vehicle or train) in one direction from the beginning of a route to the end of it; also known as a trip. 2. An operator's assignment of trips for a day of operation; also known as a work run.

Leader - a run that operates ahead of another run on the same route or line.

Open (extra run) - a run that is put into effect after other runs have been assigned and that normally will be assigned from the extra board until the next picking of runs or will be put up for bid by seniority.

Split (swing run) - two operating assignments separated by a period of time during which the operating employee is unassigned and not paid.

RUN CUTTING - The process of organizing all scheduled trips operated by the transit system into runs for the assignment of operating personnel and vehicles.

RUN NUMBER - That number assigned to a run for identification purposes.

RUNNING GEAR - The vehicle parts whose functions are related to the movement of the vehicle, including the wheels, axles, bearings, and suspension system.

RUNNING HOT (RUNNING SHARP) - Running ahead of schedule.

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SAFE - Free from danger or loss.

SAFETY CRITICAL - A designation placed on a system, subsystem, element, component, device or function denoting that satisfactory operation of such is mandatory to assurance of patrons, personnel, equipment or facility safety. Such a designation dictates incorporation of special safety design features.

SAFETY - A reasonable degree of freedom from those conditions that can cause injury or death to personnel; damage to or loss of equipment or property; and freedom from danger.

SAFETY CERTIFICATION - An element of the System Safety Program that documents the functional working of the System Safety Program, and provides a documented database from which to validate the active processes necessary to produce a safe system, ready for revenue service. Used primarily on new systems and expansions of operational properties.

SAFETY CHECKLIST - A list for examining the safety aspects of equipment, procedures, and personnel.

SAFETY CRITICAL - A designation placed on a system, subsystem, element, component, device, or function denoting that satisfactory operation of such is mandatory to assurance of patron, personnel, equipment, or facility safety. Such a designation dictates incorporation of special safety design features.

SAFETY DEVICES - Protective devices which do not alter the fundamental nature of a hazard but which do control the extent of the hazard in some manner.

SAFETY VERIFICATION - An activity of safety certification. The transit authority certifies the system as safe, usually to an outside agency. Consultants or staff verify the proper functioning of processes. (Also see VERIFICATION)

SAMPLING - The process or technique of selecting a suitable sample.

Stratified (proportional sampling) - a method of sampling that sets a quota for certain classifications of the population being sampled on the basis of the proportion of each classification in the total population (universe) or of previous information about the relative distributions in these classifications.

SCHEDULE - 1. A listing or diagrammatic presentation in time sequence of every trip and every time point of each trip, from start to finish of service, on a transit line or route. 2. In transit or railroad operations, a published table of departure or arrival times (or both) for arranged service over a transit line or route or a specific section of railroad; see also TIMETABLE.

Track - a document issued on a regular basis that describes the departments and personnel that are scheduled to occupy any portion of track during the following week. Use of a track schedule is usually associated with heavy track maintenance work.

SCHEDULED MAINTENANCE (See MAINTENANCE, SCHEDULED) - Programmed preventive maintenance.

SECONDARY TRACK - A designated track upon which trains and engines may be operated without timetable authority, trains orders or block signals, subject to prescribed signals and rules and special instructions.

SECURITY - Freedom from intentional danger.

SELF-CERTIFICATION - A procedure by which a local agency assures the federal agency that all the federal rules and regulations have been followed and adhered to; see also CERTIFICATION.

SEMANTIC DIFFERENTIAL TECHNIQUE - In attitudinal research, a method of rating the emotional connotations of words and concepts by the use of adjectives paired with their opposites.

SEMAPHORE - A signal in which day indications are given by the position of movable arm.

SERIES - Wound motor-see motor, series-wound.

SERVICE - A system or method of providing people with the use of something, for example, transportation.

Flag stop - 1. In para-transit operations, a service accessed by hail. 2. In rail operations, a non-scheduled stop that may be served if proper notice is given by a passenger or prospective passenger.

Local - 1. Transit service that involves frequent stops and consequent low average speeds, the purpose of which is to deliver and pick up transit passengers close to their destinations or origins. 2. Transit operation in which all transit units (vehicles or trains) stop at all stations. 3. Transit service in a city or its immediate vicinity, as distinguished from regional transit service or inter-urban lines.

Point deviation - public transportation service in which the transit vehicle is required to arrive at designated transit stops in accordance with a pre-arranged schedule but is not given a specific route to follow between these stops. It allows the vehicle to provide curbside service for those who request it. See also POINT-TO-POINT DEVIATION.

Regional rail (RGR) - regional rail passenger service, usually provided by railroad agencies, that consists of electric- or diesel-powered trains on grade-separated railroad lines (sometimes with protected grade crossings); see also TRANSIT SYSTEM, Commuter rail.

Revenue - 1. Transit service excluding deadheading or layovers. 2. Any service scheduled for passenger trips.

Regional transit - long bus or rail transit lines with few stations and high operating speeds. They primarily service long trips with metropolitan regions, as distinguished from city transit service and short-haul transit service.

Shuttle - 1. Service provided by vehicles that travel back and forth over a particular route, especially a short one, or one that connects two transportation systems or centers, or one that acts as a feeder to a longer route. Shuttle services usually offer frequent service, often without a published timetable. 2. For rail and other guideway systems, a service in which a single vehicle or train operates on a short line, reversing direction at each terminals.

SERVICE ATTRIBUTES - Those aspects of a transportation system that affect travel decisions about its use, such as travel time, reliability, comfort (e.g., crowding, standees), cost, ease of use, and safety.

SERVICE BRAKE (See also BRAKING, Service) - The primary train brake system(s).

SERVICE BRAKE APPLICATION - Any non-emergency brake application.

SERVICE DEPENDABILITY - The combination of reliability and maintainability characteristics of a system that describes on time system performance probability.

SERVICE FREQUENCY - The number of transit units (vehicles or trains) on a given route or line, moving in the same direction, that pass a given point within a specified interval of time, usually 1 hr; see also HEADWAY.

SERVICE VOLUME - The maximum number of vehicles that can pass a given point during a specified period while a specified level of service is maintained.

SERVICE, BASE PERIOD - The level of transit operations during the base period.

SHA - Sub-System Hazards Analysis

SHEET -

Headway - a form that contains the scheduled times that transit vehicles are to reach or depart given time points along a route or line.

Trip - 1. A sheet on which operating employees record their days work and may also record the receipts for a run. 2. A record kept of the information required by ordinance or by rule for a shift worked by the driver of a public passenger vehicle in demand-responsive service. It may also be used in line haul or charter service.

SHIFT (tour of duty, stint, trick, turn) - A part of the daily working schedule of a transit system or its employees.

SHINE TIME - (See TIME, Report.)

Overhead contact - see OVERHEAD CONTACT SHOE.

Third-rail - see THIRD-RAIL SHOE.

SHOOFLY - A temporary track to allow rail operations to bypass construction activities.

SHUNT - A bypass in an electrical circuit.

SHUNT CIRCUIT - A low-resistance connection across the source of supply, between it and the operating unit.

SHUNT IMPEDANCE (See IMPEDANCE, SHUNT) - Impedance between rails presented by a train's wheels and axles and the wheel/rail interface

SHUNTING SENSITIVITY (TRACK CIRCUIT) - The maximum impedance in ohms which, when placed at the most adverse shunting location, will cause the track circuit to indicate the presence of a train.

SIDING (passing track, side track) - A track adjacent to a main or a secondary track, for meeting, passing, or storing cars or trains.

Destination - See DESTINATION SIGN.

Head - (See HEAD SIGN.)

SIGN-UP (bidding runs, mark-up, operator pick, pick, run pick, run picking, shake-up) - The procedure by which, at regular intervals or when new service or realignments of service are implemented, operators select their regular assignment for an upcoming period (typically several months). The order of selection is usually by operator seniority and is usually specified in union contracts.

SIGN - A notice for giving direction or warning.

SIGNAL ASPECT - 1. The appearance of a fixed signal conveying an indication, as viewed from the direction of an approaching rail unit. 2. The appearance of a cab signal conveying an indication, as viewed by an observer in the cab of a rail unit.

SIGNAL AUTOMATIC - A signal that is controlled automatically by certain conditions of the track section that it protects.

SIGNAL INDICATION - The information conveyed by a signal.

SIGNAL PREEMPTION - In highway operations, an automatic or manual device for altering the normal signal phasing or the sequence of a traffic signal to provide preferential treatment for specific types of vehicles, such as buses or trains.

SIGNAL - A means of communicating direction or warning.

Automatic block - a system in which signals are actuated automatically by the presence of a train on the track section. Some block signal systems can use an electric circuit to detect the presence of any vehicle, switch positions, broken rail, and so on.

Block - a fixed signal installed at the entrance of a block to govern trains entering and using that section of track.

Cab - A signal in the train operator's cab which conveys the automatic block aspects and indicates the prevailing speed command.

Grade crossing protection - a railroad crossing flashing light signal or automatic gate actuated by the approach of a train at a grade crossing.

SIGNAL, INTERLOCKING - A wayside signal which governs movements into or within interlocking limits.

SIGNAL, APPROACH - A fixed signal used in connection with one or more signals to govern the approach thereto.

SIGNAL, ASPECT - The display or presentation of a wayside signal that provides an indication viewed from the direction of an approaching train; the appearance of a cab signal conveying an indication as viewed by an operator in the cab.

SIGNAL, AUDIBLE - A sound-producing device used for attracting attention.

SIGNAL -

Automatic - A signal activated without need for manual action.

Block - A fixed signal at the entrance to a block to govern trains entering that block.

Cab - See CONTROL SYSTEM, Cab signal.

Grade crossing protection - a railroad crossing flashing light signal or automatic gate actuated by the approach of a train at a grade crossing.

SIGNAL, BUMPING POST - A signal to advise that a bumping post at a temporary or permanent end of the track is ahead.

SIGNAL, CALL-ON - An interlocked signal aspect which permits a train to enter an occupied block at restricted speed.

SIGNAL, CLEARED - A signal which has been caused to display an aspect to proceed.

SIGNAL, COLOR LIGHT - Signals which display aspects by means of lighted color lenses.

SIGNAL, DWARF - A low home signal.

SIGNAL, FIXED (See SIGNAL, WAYSIDE) - A signal of fixed location along the track right-of-way.

SIGNAL, FLASHING LIGHT - A highway crossing signal, the indication of which is given by two horizontal red lights-flashing alternately at predetermined intervals, or a fixed signal in which the aspects are given by color and by the flashing of one or more of the signal lights.

SIGNAL, HAND - A manual signal used to govern the movement of trains.

SIGNAL, HOME - A fixed signal at the entrance to a route or block to govern trains entering that route or block.

SIGNAL IMPULSE - An automatic signal, not displaying a visible aspect, "read" and automatically responded to by on-car equipment, thereby regulating train movement.

SIGNAL INDICATION (See INDICATION, SIGNAL) - The information conveyed by the aspect of a signal.

SIGNAL, INTERLOCKING [RAIL] - A visual wayside signal containing color coded lights which governs movements into or within interlocking limits.

SIGNAL NAME (See NAME, SIGNAL) - The term used to describe the signal aspect.

SIGNAL, PROCEED - A wayside or cab signal displaying any aspect which conveys an indication which permits a train to move.

SIGNAL, STOP - A signal which displays the most restrictive aspect. A wayside signal aspect conveyed by one or more red lights, by semaphore arms in a horizontal position, or the absence of lights from a bare lamp, or a cab signal displaying the word "STOP" and a zero speed command.

SIGNAL, TIME - A signal which controls train speed by requiring that a certain time elapse in an approach block.

SIGNAL, WAYSIDE - A signal of fixed location along the track right-of-way.

SIGNAL [RAIL] - A means of communicating direction or warning.

SIGNALS, OPPOSING - Wayside signals which govern train movements in opposite directions on the same track.

SIMPLE CATENARY - (See CATENARY SYSTEM).

SIMULATION - A process or technique in which real phenomena, such as vehicle or person movements, are represented mathematically to allow study for planning purposes.

SINGLE POINT FAILURE - A causal factor whereby failure at, or by, a single point or component can create a Catastrophic (Cat I) or Critical (Cat II) hazard. Single point failures are to be eliminated by design.

SINGLE TRACK - A main track upon which trains are operated in both directions.

SKIP STOP - An operating procedure in which a train intentionally passes through a station without stopping.

SLIDE (WHEEL) - The condition wherein the wheel tread speed is less than train speed.

SLIM - Single-Sided Linear Induction Motor; see motor, single-sided linear induction.

SLIP (WHEEL) - The condition wherein the wheel tread speed is greater than the train speed.

SLIP-SLIDE SYSTEM - An onboard system for detecting and correcting wheel slips and slides.

SLOW ORDER - A location where trains must temporarily travel more slowly than maximum authorized track speed for that location.

SLOW SPEED - A speed not exceeding 15 miles per hour, except in ASC territory train will be governed by speed displayed on cab signal indicator, not to exceed 35 miles per hour.

SLT (Shuffle-Loop Transit) - (See TRANSIT SYSTEM, Shuttle-loop.)

SPACE - In the context of transportation vehicle capacity, a space is a seat or the standing area for one passenger.

SPACING - The distance between consecutive vehicles, measured front to front.

SPARE BOARD - (See EXTRA BOARD.)

SPEED - (See VELOCITY.)

Overall trip (effective operating speed, cycle speed) - in transit operations, the average speed achieved per round trip, including layover time but excluding deadheading time. It is calculated by individual trips, by running time periods, or for the entire schedule.

Running - the highest safe speed at which a vehicle is normally operated on a given roadway or guideway under prevailing traffic and environmental conditions; in some areas, also known as operating speed.

Schedule - the one-way distance between terminals divided by the scheduled travel time between the terminals; in some areas, also known as operating speed.

SPEED-FLOW RELATIONSHIP - The relationship between the flow (volume) of units on a transportation facility and the speed of those units. As flow increases, speed tends to decrease.

SPEED, CAR WASH - The speed prescribed for cars to move through a car wash; usually an automatic feature in the train control circuitry.

SPEED COMMAND - That speed limit being imposed upon a train at a given point in time by the automatic train control systems.

SPEED CONTROLLED ENGINE OR TRAIN - An engine or train equipped with speed control apparatus, including cab signal indicator, sealed application valve or switch, audible warning device and acknowledging switch, in operative condition for the direct in which it is to move.

SPEED LIMIT - A prescribed maximum speed.

SPEED LIMIT, CIVIL - The maximum speed allowed in a specified section of track as determined by physical limitations of the track structure, train design, and passenger comfort.

SPEED LIMIT, SAFETY - The maximum speed at which a train can safely negotiate a given section of track under the conditions prevailing at the time of its passage.

SPEED, LIMITED - A speed limit established by individual railroads but not, per the AAR Standard Code, to exceed 60 mph.

SPEED MAINTAINING - The automatic action of a speed regulator.

SPEED, MAXIMUM AUTHORIZED - The highest speed limit which is authorized.

SPEED, MEDIUM - A speed limit established by individual railroads but not, per the AAR Standard Code, to exceed 40 mph.

SPEED PROFILE - A plot of speed against distance traveled.

SPEED RECORDER - A device for continuously recording the speed of a train.

SPEED, REDUCED - Proceed prepared to stop short of train or obstruction

SPEED, RESTRICTED - Proceed prepared to stop short of train, obstruction, or switch not properly aligned, and to look out for broken rail, at a speed established by individual railroads but not, per the AAR Standard Code, to exceed 20 mph.

SPEED REGULATION (See SPEED MAINTAINING) - The automatic action of a speed regulator.

SPEED REGULATOR (See REGULATOR, SPEED) - An onboard vehicle subsystem, generally but not necessarily a part of the automatic train operation system, which controls acceleration and braking effort in order for the vehicle to reach and maintain a desired speed within a desired tolerance.

SPEED, SCHEDULE - The speed called for to comply with the timetable.

SPEED SENSOR - A device which detects axle, gear, or motor speed, and produces a signal at a frequency proportional to that speed.

SPEED, SLOW - A speed established by individual railroads but not, per the AAR Standard Code, to exceed 20 mph.

SPEED, YARD - A speed, used within yard limits, that will permit stopping within one-half the range of vision.

SPOTTING - Placing a train in a designated or specific location for loading or unloading.

SPREAD - (See TIME, Spread.)

Maximum - the largest permissible spread time for an operator, as specified in a labor contract or agreement.

SPRING SWITCH - A switch equipped with a spring mechanism arranged to restore the switch points to normal position after having been trailed.

SSLIM - Single-Sided Linear Induction Motor

SSPP - System Safety Program Plan

STANDARD - A document or drawing containing mandatory requirements on "how" an action or feature should be implemented. It may be adopted as law.

STANDARD ERROR OF ESTIMATE - A statistical measure of the possible differences between the actual and estimated values of a variable.

STANDARD RAIL - (See RAIL, Standard.)

STATION - 1. An off-street facility where passengers wait for, board, alight, or transfer between transit units (vehicles or trains). A station usually provides information and a waiting area and may have boarding and alighting platforms, ticket or farecard sales, fare collection, and other related facilities. It is also known as a passenger station. 2. The location to which operating employees report and from which their work originates. 3. In transportation planning, the location along a cordon line at which interviews are made. 4. In railroad operations, a place designated in the timetable by name, at which a train may stop for traffic or to enter or leave the main track, or from which fixed signals are operated.

STATION - A place designated for the purpose of loading and unloading passengers.

STEEL WHEEL - In rail systems, the specially designed cast or forged steel, essentially cylindrical element that rolls on the rail, carries the weight, and provides guidance for rail vehicles. The wheels are semi-permanently mounted in pairs on steel axles and are designed with flanges and a tapered tread to provide for operation on track of a specific gauge. The wheel also serves as a brake drum on cars with on-tread brakes.

STEM TIME - (See TIME, Pull-in; and TIME, Pull-out.

STOCK RAIL - The rail against which the point of a switch, derail, or movable point frog rests.

Far-side - a transit stop located beyond an intersection. It requires the transit units (vehicles or trains) cross the intersection before stopping to serve passengers.

Mid-block - a transit stop located at a point away from intersections.

Near-side - a transit stop located on the approach side of an intersection. The transit units (vehicles or trains) stop to serve passengers before crossing the intersection.

STOP, ABSOLUTE - A signal indication which requires a train to stop and stay stopped.

STOP AND PROCEED - A signal indication to stop and then proceed with caution not to exceed a designated speed.

STOP, EMERGENCY - The stopping of a train by an emergency brake application which, after initiated, cannot be released until the train has stopped.

STOP, PROGRAMMED - A train stop produced by closed-loop braking such that the train is stopped at a designated point according to a predetermined speed-distance profile.

STOP, SERVICE (FULL) - A train stop achieved by a brake application, other than emergency, that develops the (maximum) brake rate.

STOP SIGNAL (See SIGNAL, STOP) - A signal which displays the most restrictive aspect indicating stop.

STOP, TRAIN PROTECTION - A train stop, initiated by the automatic train protection system.

STOPPING DISTANCE (See DISTANCE, Stopping) - The maximum distance on a portion of track, which any train, operating on such portion of track at its maximum authorized speed, will travel during a full service application of the brakes, between the point where such application is initiated and the point where the train comes to a stop. (Also referred to as Safe Braking Distance)

STORAGE TIME - (See TIME, Preparation and storage.)

STREETCAR - An electrically powered rail car that is operated singly or in short trains in mixed traffic on track in city streets. In some areas it is also known as a trolley car and, primarily, in Europe, as a tram.

SU - Single Unit- (See CAR, Single-unit.)

SUB-BALLAST - A material, superior in composition to the roadbed material, that is spread on the track roadbed before the ballast is spread.

SUBSYSTEM - A defined portion of a system which is in turn composed of subsystems, component parts, or both.

SUBSYSTEM HAZARD ANALYSIS (SSHA) - A systematic analysis of a subsystem to identify, classify, and eliminate hazards.

SUBWAY - 1. That portion of a transportation system that is constructed beneath the ground surface, regardless of its method of construction. 2. An underground rail rapid transit system or the tunnel through which it runs. 3. In local usage, sometimes used for the entire rail rapid transit system, even if it is not all beneath the ground surface. 4. A pedestrian underpass.

SUPER ELEVATION - 1. In track construction, the design vertical distance that the outer rail is set above the inner rail on a curve. 2. In highway construction, the banking of the roadway on a curve.

SUPERIOR TRAIN - A train having precedence over another train.

SURVEILLANCE - A semi-formal activity initiated to allow staff a long-term overview of a process or activity. Requires formal reporting.

SWITCH - 1. The movable rails of a turnout that divert the wheels of passing rolling stock from one track to either ' one of two branching from it. 2. To move rail cars from one place to another within a defined territory, such as an industry, a yard, or a terminal.

SWITCH HEATER - A device for melting or clearing snow or ice at rail switches by means of steam, electric, or oil heat or by air jets.

SWITCH, TRACK - A pair of switch points with their fastening and operation rods providing the means for establishing a route from one track to another.

SWITCH AND LOCK MOVEMENT - A device, the operation of which performs the functions of unlocking, operating, and locking a switch, movable point frog, or derail.

SWITCH, ELECTRO-PNEUMATIC - A track switch operated by an electro-pneumatic switch and lock movement.

SWITCH, FACING POINT - A track switch the points of which face toward approaching traffic.

SWITCH, HAND OPERATED - A non-interlocked switch which can be operated only manually.

SWITCH INDICATOR (See INDICATOR, SWITCH (POSITION) - An indicator used to indicate the position of switch points.

SWITCH, INTERLOCKED - A track switch within the interlocking limits, the control of which is interlocked with other functions of the interlocking.

SWITCH POINT - A movable tapered track rail, the point of which is designed to fit against the stock rail.

SWITCH POSITION, NORMAL - The position in which a switch is aligned for train movement continuing in the same direction.

SWITCH POSITION, REVERSE - The opposite to normal position.

SYSTEM - A composite of those hardware, people or software subsystems, or any combination, which are integrated to perform a specific operational function or functions.

SYSTEM, AUTOMATIC BLOCK SIGNAL (ABS) - A series of consecutive blocks governed by block signals, cab signals, or both, actuated by train movement or by certain conditions affecting the use of a block.

SYSTEM, AUTOMATIC CAB SIGNAL - An automatic block signal system in which cab signals are provided.

SYSTEM, AUTOMATIC TRAIN CONTROL - A system which enforces speed restrictions and prevent exceeding speed restrictions by automatic brake applications; may additionally encompass automatic train operation, automatic train Protection and automatic train supervision.

SYSTEM, AUTOMATIC TRAIN STOP - A system in which the train is brought to a stop through automatic brake application if imposed restrictions are ignored.

SYSTEM, BLOCK SIGNAL - A method of governing the movement of trains into or within one or more blocks by block signals and/or cab signals.

SYSTEM HAZARD ANALYSIS (SHA) - An analysis performed on a system to identify, classify, and eliminate hazards. It identifies safety problem areas of an entire system and assesses total system risk by examining the interfaces of the subsystems.

SYSTEM, MANUAL BLOCK SIGNAL - A block signal system operated manually, usually based on information communicated by telegraph or telephone.

SYSTEM SAFETY - The application of management, engineering principles and techniques to achieve the optimum degree of safety within the constraints of operational effectiveness, time and cost, throughout all phases of the transit system life cycles, by identifying hazards and reducing associated risks.

SYSTEM SAFETY ANALYSIS - The composite term used to describe the process of providing identification, evaluation and communication of those factors and in interactions within a given system (or element thereof) which could (1) cause, (2) contribute to and (3) are needed to control inadvertent injury, death or material loss during any or all phases and activities associated with the given system's life cycle, in a logical and systematic manner.

SYSTEM SAFETY ENGINEERING - The application of scientific and engineering principles during the design, development, manufacture and operation of a system to meet or exceed established safety goals, by identifying and resolving hazards.

SYSTEM SAFETY MANAGEMENT - An element of management that defines the system safety program requirements and ensures the planning, implementation and accomplishment of system safety tasks and activities consistent with the overall program requirements.

SYSTEM SAFETY PROGRAM - The combined tasks and activities of system safety management and system safety engineering that enhance operational effectiveness by satisfying the system safety requirements in a timely, cost-effective manner throughout all phases of a system life-cycle.

SYSTEM SAFETY PROGRAM PLAN - The document containing the specific program for accomplishment of the safety goals and objectives of the TTC, including detailed responsibilities for carrying out the program.

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T-POLE - Trolley pole

TACV (Tracked Air Cushion Vehicle) - (See VEHICLE, Tracked air cushion.)

TAG AXLE - A non-powered vehicle axle that helps distribute the load.

TERMINAL - 1. The end station or stop on a transit line or route, regardless of whether special facilities exist for reversing the vehicle or handling passengers,- also known as a terminus. 2. An assemblage of facilities provided by a railroad or intercity bus service at a terminus or at an intermediate location for the handling of passengers and the receiving, classifying, assembling, and dispatching of trains or dispatching of buses; also known as a depot.

THIRD-RAIL SHOE - A metallic sliding contact attached to the trucks of electric rail vehicles for the purpose of collecting current from the third-rail distribution system.

THIRD RAIL - A rail mounted on insulators alongside the running rail which provides traction power for train operation. A rail mounted on insulators alongside the running rail which provides traction power for train propulsion.

THROUGH ROUTING - The practice of joining the ends of radial transit routes to travel through downtown instead of having each route turn back in the downtown and return to its Origin.

THROUGHPUT - 1. The volume of vehicles passing or people transported past a point or series of points during a given period of time. 2. Traffic.

TIME, ACKNOWLEDGING - A predetermined time within which an automatic brake application may be forestalled with an acknowledging device in an automatic train stop system.

TIME -

Allowance (allowed time, bonus time, dead time, hold time) - time for which an operator is paid even though the hours have not been worked or have not been worked in operating a transit unit. Forms of allowance time are pad time, report time, turn-in time, and sometimes, travel time and intervening time. See also ALLOWANCES.

Dead - Time during which no positive action is taking place. (See TIME ,Delay; Time, Reaction).

Deadhead (not-in-service time) - time spent moving a revenue vehicle in non-revenue service.

Layover (recovery time, relay time, spot time, turn-around time) - time built into a schedule between arrivals and departures, used for the recovery of delays and preparation for the return trip. The term may refer to transit units (also known as vehicle layover) or operators.

Linked trip (overall travel time, total travel time) - in transportation planning, the time duration of a linked trip, that is, from the point of origin to the final destination, including waiting and walking time at transfer points and trip ends.

Preparation and storage - the time in minutes paid to an operator to prepare or store the transit unit when pulling out and in, that is, report time and turn-in time combined.

Pull-in - 1. In transit operations, the time at which the transit unit returns to the yard or garage; see also TIME, Turn-in. 2. In some transit operations, the deadhead time assigned to move a transit unit (vehicle or train) from its last scheduled stop to the storage area; also known as stem time.

Pull-out - 1. In transit operations, the scheduled time at which the transit unit leaves the yard or garage; see also TIME, Report. 2. In some transit operations, the deadhead time assigned to move a transit unit (vehicle or train) from the storage area to its first scheduled stop; also known as stem time.

Response - in demand-responsive operations, the time between a passengers request for service and the passenger pickup.

Report - 1. The time at which operators must report if they are to work an assignment. 2. The time at the beginning of a run that operators use to prepare themselves for duty and their vehicles for service before leaving the yard or garage. This time, usually 5 or 10 minutes, may be paid or unpaid. It is also frequently known as preparation time, pull-out time, or (only if paid) report time allowance. See also TIME, Pull-out. 3. In some properties, the time spent by an operator waiting for an assignment or protecting service in event of absence of another operator; also known as shine time.

Running - the actual time required for a transit unit (vehicle or train) to move from one point to another, excluding time for stops.

Spread (spread, outside time) - total elapsed time from the beginning to the end of a days assignment, including all breaks, time between runs, travel time, and deadheading.

Stopped - time on a trip spent stationary because of the stoppage of other traffic.

Transfer - the time required to effect a change of mode or to transfer between routes or lines of the same mode.

Turn-in - the time at the end of a run that allows the operators to clear their responsibilities (e.g., read farebox, turn in tickets) and prepare their vehicles for storage. The time may be paid or unpaid and may or may not be included in platform time. It is also frequently known as clear time, pull-in time, or storage time; see also TIME, Pull-in.

Unlinked trip - in planning, the time duration of an unlinked trip, that is, one made on a single vehicle.

TIME, DELAY - The time which elapses after a controlling signal changes until the controlled output begins to change.

TIME, DOWN - The total time during which the equipment is not in acceptable operating condition. Down time starts with a failure event and ends at the completion of repair and functional checks/inspections.

TIME, REACTION - The time used by equipment, operator, or both, that elapses between the moment an action is called for and when the desired result occurs.

TIME, RELEASE - A device used to prevent the operation of a unit until after the expiration of a predetermined time interval after the device has been actuated.

TIME, UP - The time during which equipment is either operating satisfactorily or is in an operable state and ready to be placed in operation. Up time is initiated by a completion of-repair and is terminated by a failure event.

TIMED TRANSFER SYSTEM (TTS) - A transit network consisting of one or more nodes (transit centers) and routes or lines radiating from them. The system is designed so that transit vehicles on all or most of the routes or lines are scheduled to arrive at a transit center simultaneously and depart a few minutes later, thus transfers among all the routes and lines involve virtually no waiting. TTS is typically used in suburban areas and for night service; in other words, for those cases in which headways are long (10-60 min). Transit centers (also known as timed transfer focal points) are ideally located at major activity centers, such as suburban towns, campuses, and shopping centers.

TIMETABLE - 1. Usually refers to a printed schedule for the public. 2. A listing of the times at which transit units (vehicles or trains) are due at specified time points; also known as a schedule. 3. In railroad operations, the authority for the movement of regular trains subject to the rules. It contains classified schedules with special instructions for the movement of trains and locomotives.

TLV (Tracked Levitated Vehicle) - (See VEHICLE, Tracked levitated.)

TORQUE - The twisting force required to turn a bolt or a rotating shaft.

TRACK - 1. An assembly of rails, supporting ties, and fastenings over which rail vehicles travel. 2. A linear cam or way that physically guides (and usually supports) any matching vehicle used for transportation. 3. The width of a wheeled vehicle from wheel to wheel, usually measured between the outsides of the rims. 4. The distance between the centers of the tread of parallel wheels, as of an automobile.

TRACK CIRCUIT - An electrical circuit that makes use of both rails to detect train occupancy of the track and, in response, to actuate signals, train control devices, and grade crossing protective equipment.

TRACK INSTRUMENT - A device in which the vertical movement of the rail or the blow of a passing wheel operates a contact to open or close an electric circuit.

TRACK MILES (track kilometers) - The sum of the one-way linear miles (kilometers) of all trackage in a system, including all main track and trackage in yards, car barns, switches, and turnouts.

Revenue (revenue track kilometers) - the number of miles (kilometers) of track used in passenger-carrying service.

Service (service track kilometers) - the number of miles (kilometers) of track used exclusively in non-revenue service.

TRACK RELAY - A relay that receives all or part of its operating energy through conductors (of which the track rails are an essential part) and that responds to the presence of a train on the track.

TRACK TRIP - A device that is located near the track and interconnected with the signal system so that it triggers the emergency brakes of any train that passes when the signal is red.

TRACK BRAKE - A friction brake, usually activated electromagnetically, which compresses against the running rails.

TRACK CAR - Equipment, not classified as an engine, which is operated on track for inspection or maintenance. It may not shunt track circuits or operate signals and will be governed by rules and special instruction for trains other than passenger trains.

TRACK INDICATOR - A device used to indicate the occupancy of a given track section.

TRACK LAYOUT - An organized assemblage of track; the depiction thereof for control purposes.

TRACK, MAIN - A track extending through yards and between stations, upon which trains are operated by timetable or train order, or both, or the use of which is governed by signals.

TRACK RELAY - A relay receiving all or part of its operating energy through conductors of which the track rails are an essential part.

TRACK, REVERSIBLE - A section of track on which the prescribed direction of running can be reversed if it is unoccupied and the opposing home signal is at "STOP"

TRACK, SINGLE - A main track on which trains are operated in both directions.

TRACKSWITCH (See TURNOUT) - A pair of switch points which, with their fastenings and operating rods, provide the means for establishing a route from one track to another.

TRACK, TRANSFER - A track in a yard area where the transfer between main track and manual yard modes of operation takes place.

TRACKWORK - The rails, switches, frogs, crossings, fastenings, pads, ties, and ballast or track-support slab over which rail cars are operated. Special (track special work) - all rails, track structures, and fittings, other than plain unguarded track, that is neither curved nor fabricated before laying.

Special (track special work) - all rails, track structures, and fittings, other than plain unguarded track, that is neither curved nor fabricated before laying.

TRACTIVE EFFORT (tractive force) - The force exerted by a locomotive or other powered vehicle on its driving wheels. It is equal to the weight on the driving wheels times the coefficient of adhesion.

TRAFFIC - In traffic engineering and transportation planning the vehicles, people, or both that pass a specified point during a given period.

Diverted (diverted demand) - a component of traffic that has changed from its previous path of travel to another route without a change in origin, destination, or mode of travel; for example, traffic diverted from a major street to a new expressway, roughly parallel to the street, because of savings in time or distance.

Induced (induced demand) - the added component of traffic volume that did not previously exist in any form but that results when new or improved transportation facilities are provided, for example, trips to a shopping center by the transit dependent when transit service to the shopping center is started.

TRAFFIC CONTROL DEVICE - A sign, signal, marking, or other device placed on or adjacent to a street or highway, by authority of a public body or official that has jurisdiction, to regulate, warn, or guide traffic.

Grade crossing - (See GRADE CROSSING TRAFFIC CONTROL DEVICE.)

TRAILING POINT SWITCH - A track switch, the points of which face away from traffic approaching.

TRAIN - A consist of one or more cars combined into an operating unit.

Elephant - a train of two or more small passenger conveyances, which may be open or closed, pulled slowly by a power tractor unit. The trailer units follow essentially the same path as that taken by the tractor unit. Elephant trains are typically operated at major activity centers, such as expositions or boardwalks.

Local - a train that stops at every station on the line; see also SERVICE, Local.

Push-pull - a locomotive and a set of cars equipped with one or more cab cars from which the locomotive can be controlled. The train is either pulled and controlled from the locomotive in the conventional manner or pushed by the locomotive and controlled from the leading car.

TRAIN BERTH - In rail operations, the space designated for a train of given length to occupy when it is stopped at a station platform, in a terminal, on a transfer track, or at some other designated place.

TRAIN CONTROL RECEIVER (See RECEIVER, TRAIN CONTROL) - A device on a vehicle so placed that it is in position to be influenced inductively or actuated by an automatic train control or cab signal roadway element.

TRAIN -CONTROL TERRITORY - The portion of a railroad division or district that is equipped with an automatic train control system.

TRAIN DENSITY - 1. The number of trains that can be operated safely over a segment of railroad in each direction during a 24-hr period. 2. The average number of trains that pass over a specified section of railroad in a specified period.

TRAIN DESCRIBER - A document or display device that gives information about the origin, destination, class, or character of trains, locomotives, or rail cars that are moving or to be moved between given points.

TRAIN DETECTION - A method by which the presence of a train in a block is known.

TRAIN IDENTIFICATION - A method of identifying trains using information such as train number, destination, length, or a combination of these elements. May be accomplished automatically for such functions as routing.

TRAIN LENGTH -The number of units (cars) in a train; its overall length in dimensions of distance.

TRAIN NUMBER - Numerical designation of a train.

TRAIN OF SUPERIOR RIGHT - A train given precedence by train order.

TRAIN OPERATION - The way in which a train is operated, for example, automatic with automatic over-speed control, or manual with either automatic or manual speed control, or skip-stop.

TRAIN OPERATOR - That person on board a train having direct and immediate control of the movement of a train.

TRAIN, OPPOSING - A train, the movement of which is in a direction opposite to and toward another train on the same track.

TRAIN ORDERS- Instructions, usually written, used to govern train operations manually.

TRAIN PROTECTION (See AUTOMATIC TRAIN PROTECTION) - That subsystem within the automatic train control system which maintains safe train operations through a combination of train detection, train separation, and interlocking.

TRAINLINE - Circuits routed between cars by means of couplers or jumper cables so that power or control signals may be transmitted to other cars of the train.

TRAILING MOVEMENT (See MOVEMENT, TRAILING) - The movement of a train over the points of a switch which face in a direction in which the train is moving.

TRANSDUCER - An electrical or mechanical device that converts physical motion into electrical impulses that can be easily counted and processed by a computer. Examples of transducers include fuel flow meters, vehicle odometers, and passenger-counting infrared beams.

TRANSFER - 1. A passenger's change from one transit unit (vehicle or train) or mode to another transit unit or mode. 2. A slip of paper, card, or other instrument issued to passengers (either free or with a transfer fee) that gives the right to change from one transit unit or mode to another according to certain rules that may limit the direction of travel or the time in which the change may be made.

TRANSIT CENTER - A transit stop or station at the meeting point of several routes or lines or of different modes of transportation. It is located on or off the street and is designed to handle the movement of transit units (vehicles or trains) and the boarding, alighting, and transferring of passengers between routes or lines (in which case it is also known as a transfer center) or different modes (also known as a modal interchange center or an intermodal transfer facility).

TRANSIT DEPENDENT - Having to rely on transit services instead of the private automobile to meet ones travel needs; see also RIDER, Captive; RIDER, Captive transit; and TRANSPORTATION DISADVANTAGED.

TRANSIT DISTRICT - A geographical or political division created specifically for the single purpose of providing transportation services. It is a separate legal entity and usually possesses the authority to impose a property tax. Such political divisions may also be known as a transit agency or transit authority; see also PROPERTY.

TRANSIT SYSTEM - The facilities, equipment, personnel, and procedures needed to provide and maintain public transit service.

Commuter rail - a passenger railroad service that operates within metropolitan areas on trackage that usually is part of the general railroad system. The operations, primarily for commuters, are generally run as part of a regional system that is publicly owned or by a railroad company as part of its overall service. In some areas it is called regional rail.

Continuous - a system that provides continuous movement, for example, a moving belt or escalator. The whole system or portions of it may operate at variable speeds.

Dual-mode - a broad category os systems wherein vehicles may be operated in both of two different types of operation or propulsion, for example, manually steered and guided, on highways and on guideways, or with diesel and electric traction.

Monorail - a transit system consisting of vehicles supported and guided by a single guideway (rail or beam), usually elevated. The basic types are as follows: supported, in which vehicles straddle the guideway or are laterally supported by it; and suspended, in which vehicles hang directly below the guideway (symmetrical monorail) or to one side of it (asymmetrical monorail). Supported monorails are stabilized by gyro, overhead rails, or lateral guidewheels on both sides of the beam (saddle monorail).

Personal rapid (PRT) - a theorectical concept for an automated guideway transit system that would operate small units (two to six passengers) under computer control over an elaborate system of guideways. Off-line stations would provide demand-responsive service (except, perhaps, during peak periods) with headways of 3 sec or less. Individuals or small acquainted groups would use a unit to travel between origin and destination stations without stopping.

Pre-metro - a light rail transit system designed with provisions for easy conversion to rail rapid transit.

Rail rapid (heavy rail transit, rapid rail transit) - a transit system that generally serves one urban area, using high-speed, electrically powered passenger rail cars operating in training in exclusive rights-of-way, without grade crossing (Chicago is an exception) and with high platforms. The tracks may be in underground tunnels, on elevated structures, in open cuts, at surface level, or any combination thereof. Some local terms used for rail rapid transit are the elevated, the metro, the metropolitan railway, the rapid, the subway, the underground.

Semi-metro - a light rail transit system that uses exclusive right-of-way for much of its length, usually at surface grade but occasionally in tunnels or on aerial structures.

Shuttle-loop (SLT) - an automated guideway transit system in which transit units (vehicles or trains) operate along shuttle or loop guideways with few or no switches. It usually has on-line stations.

Streetcar (street railway, tramway, trolley system) - a street transit system consisting of electrically powered rail vehicles operating in one- to three-car transit units, mostly on surface streets with mixed traffic.

TRANSIT SYSTEM (See RAIL RAPID TRANSIT SYSTEM) - An electrified fixed guideway transportation system, utilizing steel rails, usually operating on an exclusive grade-separated right-of-way for the mass movement of passengers within a city or metropolitan area and consisting of its fixed way, transit vehicles and other rolling stock, power system, maintenance facilities, and other stationary and movable apparatus and equipment, and its operating practices and personnel.

Light rail (LRT) - as defined by the TRB Subcommittee of Light Rail Transit, a metropolitan electric railway system characterized by its ability to operate single cars or short trains along exclusive rights-of-way at ground level, on aerial structures, in subways, or occasionally, in streets, and to board and discharge passengers at track or car floor level.

Light rail rapid (LRRT) - light rail transit with exclusive, grade-separated right-of-way for the entire system. It may have low- or high-level platforms and visual or signal control.

Monorail - a transit system consisting of vehicles supported and guided by a single guideway (rail or beam), usually elevated. The basis types are as follows: supported, in which vehicles straddle the guideway or are laterally supported by it; and suspended, in which vehicles hang directly below the guideway (symmetrical monorail) or to one side of it (asymmetrical monorail). Supported monorails are stabilized by gyro, overhead rails, or lateral guidewheels on both sides of the beam (saddle monorail).

TRANSIT SYSTEM AVAILABILITY - A measure of the capability of a transit system to be used by potential passengers, including such factors as the hours the system is in operation, route spacing, and accessibility to the physically handicapped.

TRANSIT SYSTEM FAIL SAFETY -The integration of the design, procedures, people and all other elements of a transit system using the principles of fail safety and system safety in such a manner that equipment failures or personnel errors, or combinations of both, shall not result in an increased hazard level.

TRANSIT UNIT - One or more transit vehicle coupled and operated together. The term includes single vehicles (bus, rail, or other guideway) and multi-car trains (rail or other guideway) bidirectional or double-ended; (See DOUBLE-ENDED TRANSIT UNIT.)

TRANSITWAY - A dedicated right-of-way, most commonly in a mall, that is used by transit units (vehicles or trains), usually mixed with pedestrian traffic.

TRANSPORTATION DISADVANTAGED (LOW-MOBILITY GROUP) - People whose range of transportation alternatives is limited, especially in the availability of relative easy-to-use and inexpensive alternatives for trip making. Examples include the young, the elderly, the poor, the handicapped, and those who do not have automobiles See also TRANSIT DEPENDENT; RIDER, Captive; and RIDER, Captive transit.

TRANSPORTATION SYSTEM - 1. A system that provides for the movement of people, goods, or both. 2. A coordinated system made up of one or several modes serving a common purpose, the movement of people, goods, or both.

Air cushion - a surface transportation system that uses vehicles that are supported above the guideway by a thin layer (cushion) of air.

High-speed ground (HSGT) - a guided transportation system with exclusive right-of-way and vehicles intended to serve a densely traveled corridor at cruise speeds of 124 mph (200 km/h) and greater.

TRANSPORTATION SYSTEM MANAGEMENT (TSM) - That part of the urban transportation planning process undertaken to improve the efficiency of the existing transportation system. The intent is to make better use of the existing transportation system by using short-term, low-capital transportation improvements (LCTI) that generally cost less and can be implemented more quickly than system development actions.

TRANSPORTATION SYSTEM MANAGEMENT ALTERNATIVE (Low capital alternative, no-build alternative, TSM alternative) - The planning option of not building a new transportation facility, such as a new highway or rail system, but instead improving the already existing transportation system, for example, by making streets one way or increasing public transportation services; see also NO-ACTION ALTERNATIVE and TRANSPORTATION SYSTEM MANAGEMENT.

TREAD BRAKE UNIT - A unit composed of brake shoe and apparatus to apply the brake shoe to the wheel tread.

TRIP - 1. A one-way movement of a person or vehicle between two points for a specific purpose; sometimes called a one-way trip to distinguish it from a round trip. 2. In rail operations, a mechanical lever or block signal that, when in the upright position, activates a trains emergency braking system. 3. The movement of a transit unit (vehicle or train) in one direction from the beginning of a route to the end of it; also know as a run.

Home- based - a trip that has either it origin or destination at the travelers residence.

In-bound - a trip toward the central urban area, into the central business district, or to a timed transfer point or major activity center.

Linked (linked journey, linked passenger trip) - a trip from the point of origin to the final destination, regardless of the number of modes or vehicles used.

Passenger - one passenger making a one-way trip from origin to destination.

Unlinked - 1. A trip made in a single vehicle. 2. The boarding of one transit vehicle in revenue service; also known as an unlinked passenger trip. 3. Any segment of a linked trip.

TRIP ASSIGNMENT (flow distribution, traffic assignment) - In planning, a process by which trips, described by mode, purpose, origin, destination, and time of day, are allocated among the paths or routes in a network by one of a number of models; see also URBAN TRANSPORTATION MODELING SYSTEM and MODEL, SEQUENTIAL.

Stochastic - a probabilistic trip assignment technique that allocates trips with deviation from the minimum time route on the basis of differences in travel time.

Diversion - a trip assignment technique that allocates trips to alternate routes on the basis of the relative times or distances (or both) involved.

TRIP DISTANCE -

Linked (total travel distance) - the distance traveled on a linked trip, that is, the distance from the point of origin to the final destination, including the walking distance at trip ends and at transfer points.

Unlinked - the distance traveled on an unlinked trip, for example, a trip on a single vehicle.

TRIP END - A trip origin or a trip destination.

TRIP GENERATION - In planning, the determination or prediction of the number of trips produced by and attracted to each zone; see also URBAN TRANSPORTATION MODELING SYSTEM and MODEL, Sequential.

TRIP GENERATOR - A land use from which trips are produced, such as a dwelling unit, a store, a factory, or an office.

TRIP LENGTH FREQUENCY DISTRIBUTION - A list or diagram of the number or the percentage of trips made at various intervals of trip time or distance.

TRIP MATRIX - In planning, an array of the number of trips made between each zone pair; see also TRIP TABLE.

TRIP TABLE - A table that presents the number of trips between zones, classified by mode, purpose, time period, type of vehicle, or other category; see also TRIP MATRIX.

TRIP COCK - A mechanical device located on the train which, when hit by a trip stop, results in an emergency brake application.

TRIP STOP (ARM) - A mechanical arm located on the wayside which, when in the up (trip) position, initiates an emergency brake application on a train which passes it.

TRIP STOP, FIXED - A trip stop permanently positioned in the tripping position.

TRIPPER - 1. In transit operations, a short piece of work that cannot be incorporated into a full day's run, usually scheduled during peak hours. 2. In transit operations, a short work schedule for operators, usually 1-3 hr long; for example, during peak periods. 3. On some transit properties, a short run that is less than 8 hr long. 4. On some transit properties, a transit service that operates on only a portion of a route, usually at peak hours.

TROLLEY - 1. An apparatus, such as a grooved wheel or shoe, at the end of a pole, used for collecting electric current from an overhead wire and transmitting it to a motor of a street- car, trolleybus, or similar vehicle, where it is used for traction and other purposes. 2. Sometimes used locally as another term for a streetcar.

TROLLEY POLE - A swiveling spring-loaded pole attached on the roof of an electric bus or car that holds a wheel or sliding shoe in contact with the overhead conductor (which usually takes the form of a thick wire), collects current from it, and transmits the current to the motor on the vehicle, for example, a streetcar or trolleybus.

TROLLEY WIRE (See CATENARY SYSTEM) - An overhead wire from which a transit vehicle collects propulsion and auxiliary power.

TRUCK (bogie, British usage) - In rail transportation, a rail vehicle component that consists of a frame, normally two axles, brakes, suspension, and other parts, which supports the vehicle body and can swivel under it on curves. A truck usually also contains traction motors.

TRUCK HUNTING - In rail operations, lateral instability of a truck, generally occurring at high speed and characterized by the shifting of one or both wheel sets from side to side so that the flanges strike the rail. The resulting motion of the rail car causes excessive wear in car and truck components and creates potentially unsafe operating conditions.

TUNNEL - 1. An enclosed passageway, as for trains, automobiles, and so on, through or under an obstruction, such as a city, mountain, river, or harbor. 2. An underground passage.

TURN BACK - 1. In transit operations, to cut short a transit trip (to turn back before reaching the end of the route or line), usually to get back on schedule or to meet peak passenger demands; also known as a short turn. 2. In rail operations, a point along a track at which a train may reverse direction.

TURNBACK - A point along a track at which a train may reverse direction.

TURNOUT - 1. In rail transportation, the assembly of a switch and a frog with closure rails by which rolling stock or trains can travel from a track onto either one of two diverging tracks; also known as a track switch. 2. A short side track or passage that enables trains, automobiles, and similar vehicles to pass one another. 3. A short passing lane on a highway.

TURNOVER POINT - A point along a transit route at which a large proportion of passengers leave and board a transit unit.

TURNSTILE, FARE - Registering-see fare-registering turnstile.

TWO OR MORE TRACKS - Two or more main tracks upon which trains are operated as designated by the rules and special instructions.

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U

UNLINKED - 1. A trip made in a single vehicle. 2. The boarding of one transit vehicle in revenue service; also known as an unlinked passenger trip. 3. Any segment of a linked trip.

UNSAFE CONDITION - Any condition which endangers life or property.

UNSCHEDULED MAINTENANCE (See MAINTENANCE, UNSCHEDULED) - Maintenance action initiated by the malfunction of equipment.

UP TIME - The time during which an equipment is either operating satisfactorily or is in an operable state and ready to be placed in operation. Up time is initiated by a completion of repair and is terminated by a failure event.

UP TIME RATIO (STEADY STATE AVAILABILITY) - The ratio of system up time to the total time. It is also expressed in terms of means as: MTBF/MTBF + MTTR

URBAN TRANSPORTATION MODELING SYSTEM (UTMS, FOUR-STAGE MODEL, FOUR-STEP PLANNING PROCESS) - A system of models used in transportation planning as an approach to urban travel demand modeling. It consists of four major stages: trip generation; trip distribution; modal split; and trip assignment. UTMS predicts the number of trips by type, time of day, zonal original and destination, mode, and routes.

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V

VALVE, BRAKE - A separate operator's control for the purpose of applying and releasing pneumatic friction brakes.

VCR - Video Cassette Recorder

VDC - Volts Direct Current

VEHICLE (See TRANSIT CAR) - An electrically propelled, passenger carrying rail vehicle.

VEHICLE - An electrically propelled passenger carrying rail vehicle, or a diesel powered passenger carrying motor bus.

Air cushion (ACV, ground effect machine) - any vehicle supported by a cushion of air.

Revenue - a vehicle used to provide passenger transit service for which remuneration is normally required. It is distinct from non-revenue equipment, which is used to build or maintain facilities, provide supervision, and so on.

Tracked air cushion (TACV) - a laterally guided vehicle that is suspended above the track by an air cushion system.

Tracked levitated (TLV) - a laterally guided vehicle that is suspended above the track by magnetic levitation.

VEHICLE SIGNAL-ACTUATING DEVICE - A device to control traffic signals that is activated by vehicles.

VELOCITY (SPEED) - The distance passed per unit of time, or the rate of change in location relative to time. For transportation vehicles, it is usually measured in miles (kilometers) per hour.

Cruise (cruise speed) - the forward velocity that a vehicle maintains when it is nether accelerating nor decelerating. It is usually less than maximum design speed but can be equal to it.

Effective (average speed) - the average velocity at which a vehicle travels. For transit vehicles, it includes dwell times at stops or stations, acceleration, and deceleration.

Maximum theoretical - the highest theoretical velocity that a vehicle is physically capable of achieving.

VERIFICATION - A conformation of the accuracy, or correctness in comparison with a standard. As applied in safety certification, a safety verification is usually performed by an agent of the Authority and confirms an item or activity to an identified standard; a safety certification is an attesting by the Authority that the system is safe for patron use. Safety verification provides the audit trail of documented proof leading to a credible certification.

VITAL CIRCUIT (See CIRCUIT, VITAL) - Any circuit which affects the safety of train operations.

VITAL COMPONENT OR CIRCUIT - Any device, circuit or software module used to implement a vital function.

VITAL FUNCTION - A system, subsystem, equipment, or component that provides a function critical to safety.

VOLTAGE -

High - in rail transportation, the prime propulsion power voltage supplied by an overhead wire or third rail, usually 500 - 1,500 V direct current.

Low - in rail transportation, the voltage used for most auxiliary systems (e.g. Illumination, fans, public address systems), usually 24 or 72 V direct current or 110-240 V alternating current.

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W

WARNING DEVICES - Sensors that monitor or detect conditions and provide visible and/or audible alerting signals as desired for selected events.

WAYSIDE EQUIPMENT (See EQUIPMENT, WAYSIDE) - Train control or movement apparatus which is located along the track or wayside as opposed to the control center or other remote location.

WAYSIDE SIGNAL (See SIGNAL, WAYSIDE) - A signal of fixed location along the track right-of-way.

WAYSIDE SIGNAL MODE, REGULATED SPEED -Operation in the wayside signal mode with the use of a speed regulator manually set by the operator.

WAYSIDE TRAIN STOP (See TRIP STOP) - A mechanical arm located on the wayside which, when in the up (trip) position, initiates an emergency brake application on a train which passes it.

WORST CASE ANALYSIS - Analysis of the worst case parameters of a system or subsystem.

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X

X-OVER - Crossover

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Y

YARD - A system of tracks within defined limits provided for making up trains, storing cars and other purposes, over which movements not authorized by timetable or train-order may be made, subject to prescribed signals and rules or special instructions.

YARD LIMITS - A portion of a single main track between yard limit boards, as specified by special instructions.

YARD SPEED (See SPEED, YARD) - A speed, used within yard limits, that will permit stopping within one-half the range of vision.

YARD, STORAGE - A system of tracks within defined limits for making up trains and storing transit cars.

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