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