ASME/IEEE RVTIS Abbreviations/Definitions Version 19

ABBREVIATIONS

ABBREV. Abbreviations

Description meaning of the abbreviation

TRB indicates if the abbreviation appears in the TRB Glossary

Usage indicates the draft standard using the abbreviation

ABBREV.	DESCRIPTION	TRB	USAGE
AAR	Association of American Railroads	N	1570
AASHTO	American Association of State Highway and Transportation Officials	N	1570
ACSES	advanced civil speed enforcement system	N	1482/1482.1
AGT	automated guideway transit	Y	1475
Ah	Ampere hour	N	1536
ANSI	American National Standards Institute	N	1473/14h76/1536
API	applications interface	N	1473
APTA	American Public Transportation Association (formerly American Public Transit Association)	N	1474.1/1536
AREMA	American Railway Engineering and Maintenance of Way Association	N	1478/1570
ASCE	American Society of Civil Engineers	N	1483/1478/1474.1
ASTM	American Society for Testing and Materials	N	1478/1536
ATC	automatic train control	Y	1475/1474.1/1474.2/1482 1482.1
ATO	automatic train operation	Y	1475/1474.1/1474.2/1482
ATP	automatic train protection	Y	1475/1474.1/1483/1474.2 1482.1
ATPM	automatic train protection manual	N	Not Used
ATS	automatic train speed	N	1482/1482.1
ATS	automatic train stop; automatic train supervision	Y	1475/1474.1/1474.2
AWG	American Wire Gauge	N	1473
AWS	auxiliary wayside system	N	Not Used
BC	battery charger	N	1476
CBTC	communications-based train control	N	1474.1/1474.2/1482 1482.1
CENELEC	European Committee for Electrotechnical Standardization	N	1483
CFR	Code of Federal Regulations	N	1482/1482.1
DMU	diesel multiple unit	Y	1475
DOT	United States Department of Transportation	Y	1476/1536
EIA	Electronics Industry Association	N	1473
EMC	electo magnetic compatibility	N	1536
EMI	electro magnetic interference	N	1476/1478
EMU	electric multiple unit	N	1475
FFT	functional fault tree	N	1483
FMEA	failure modes and effect analysis	N	1483
FRA	Federal Railroad Administration (of the DOT)	Y	1476/1482/1482.1/1536
FTA	Federal Transit Administration (of the DOT)	N	1476/1536
FTA	fault tree analysis	N	1483
GPS	global positioning system	N	1482.1
GUI	graphical user interface	N	1474.2
HEP	head end power	N	Not Used
HRV	heavy rail vehicle	N	1475
HVAC	heating, ventilating and air conditioning	N	1476
IEC	International Electrotechnical Commission	N	1473/1478/1483/1536
IEEE	Institute of Electrical and Electronics Engineers	N	1474.1/1476/1474.2 1478/1482.1/1483/1570/1536
ISO	International Standards Organization	N	1483
ITE	Institute of Transportation Engineers	N	1473/1570
ITS	intelligent transportation system	N	1482.1/1482
IVPS	intermediate voltage power supply	N	1476
LCD	liquid crystal display	N	1477/1475
LED	light emitting diode	N	1477/1475/1482.1
LSB	local sensor bus	N	1473
LRV	light rail vehicle	Y	1475
LVB	local vehicle bus	N	1473
LVPS	low voltage power supply	N	1476/1536
MDS	monitoring and diagnostic system	N	1482.1/1482
ML	multi-function-vehicle bus to local sensor bus	N	1473
MTBE	mean time between event	N	Not Used
MTBF	mean time between failure	N	1474.1
MTBFF	mean time between functional failure	N	1474.1
MTBHE	mean time between hazardous event	N	1474.1/1483
MTTR	mean time to repair	N	1474.1
MTTRS	man time to restore service	N	1474.1
MVB	multi-functional vehicle bus	N	1473
NEC	National Electrical Code (also known as NFPA 70)	N	1476/1536
NEMA	National Electrical Manufacturers Association	N	1476/1536/1570
NFPA	National Fire Prevention Association	N	1476/1536
NMT	network management	N	Not Used
NOAA	National Oceanic and Atmospheric Administration	N	1478
NTCIP	national transportation communications for intelligent transportation system (ITS) protocol	N	1570
O&SPA	operational and support hazard analysis	N	Not Used
OSI	open system interconnect	N	1473
PCMCIA	Personal Computer Memory Card International Association	N	1477
PD	process data	N	1473
PHA	preliminary hazard analysis	N	1483
PV	presentation variables	N	1473
PWM	pulse width modulation	N	1475
RF	radio frequency	N	1474.1
ROSIN	railway open system interconnection network	N	1473
RTP	real time protocols	N	Not Used
SAE	Society of Automotive Engineers	N	1478
SHA	safety hazard analysis	N	Not Used
SNVT	standard network variable type	N	1473
SSHA	subsystem hazard analysis	N	1483
SSIHA	subsystem interface hazard analysis	Y	1483
SSn-FTA	subsystem fault tree analysis	N	1483
SSPP	system safety program plan	N	1474.1
SVP	safety verification plan	N	1483
TCN	train communications network	N	1473
TCRP	Transportation Cooperative Research Program	N	1473
TCS	train control system	N	1477
TNM	train network management	N	Not Used
TRB	Transportation Research Board	Y	1475/1473/1536
UIC	Union International des Chemins de Fer	N	Not Used
UL	Underwriters Laboratory	N	1536
VOBC	vehicle on-board (master) control	N	1475
WTB	wire train bus	N	1473

DEFINITIONS

Word word being defined

S status of definition

A approved by ballot P published in a standard

Definition meaning for the word

TRB indicates whether the word appears in the TRB Glossary

D – different M – modified N – no Y - yes

Usage the first reference indicates standard where word was first defined and/or accepted. Usage within other standards follows the first usage.

WORD	S	DEFINITION	TRB	USAGE
actual weight	P	The measured weight of a finished, ready-to-run vehicle. Synonym: empty.	N	1475
adhesion (coefficient of)	P	During rolling contact, the ratio between the longitudinal tangential force at the wheel-rail/running surface interface and the normal force.	N	1475
aging factor	A	A quantitative factor expressing the degradation in the ability of the battery, due to usage, to deliver electrical energy under specified conditions such as, but not limited to, operating ambient temperature, cycling, depth of charge, and maintenance practices.	N	1476
alertness function	P	A device or system which monitors the operator for signs of incapacitation, usually by requiring movement or response to take place within a prescribed period of time.	N	1475
ambient temperature	A	The ambient temperature is the temperature at which a test chamber shall be maintained while testing the equipment for verification of compliance with this standard.	N	1478
apparatus	P	A device or system of devices that performs a distinct function within a basic operating unit, including a device or system of devices whose principal function is data communications.	N	1473
apparatus interoperability	P	The ability of any specific apparatus to communicate with other apparatuses in such a way that it can successfully replace another apparatus of the same apparatus type without any requirement for manual configuration other than the address or unique identifier of the replacement apparatus.	N	1473
apparatus type	P	A pre-defined configuration that, when adhered to by a given apparatus, makes it possible for that apparatus to achieve apparatus interoperability, without restriction on the internal constructional details of the apparatus concerned.	N	1473
authority	P	A geographical or political division created specifically for the single purpose of providing transportation service.	Y	1475 1476 1536
authority having jurisdiction	P	That entity that defines the contractual (including specification) requirements for the procurement.	N	1475 1473 1474.1 1476 1474.2 1478 1536 1570
automated guideway transit	P	Any guided transit mode with fully automated operation (i.e. no crew on the train). The term usually refers, however, only to guided modes with small and medium-sized vehicles that operate on exclusive right-of-way.	Y	1475
automatic train control	P	The system for automatically controlling train movement, enforcing train safety, and directing train operations. ATC must include automatic train protection (ATP) and may include automatic train operation (ATO) and/or automatic train supervision (ATS).	M	1475 1474.1 1474.2
automatic train operation	P	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 or other functions otherwise assigned to the train operator.	M	1475 1474.1 1474.2
automatic train protection	P	That subsystem within the automatic train control system which maintains fail-safe protection against collisions, excessive speed, and other hazardous conditions through a combination of train detection, train separation, and interlocking.	M	1475 1474.1 1474.2
automatic train stop	P	A wayside system that works in conjunction with equipment installed on the vehicle to apply the brakes at designated restrictions or on a dispatcher’s signal, should the operator not respond properly.	M	1475
automatic train supervision	P	That subsystem within the automatic train control system which monitors trains, adjusts the performance of individual trains to maintain schedules, and provides data to adjust service to minimize the inconveniences otherwise caused by irregularities. Note - The ATS subsystem also typically includes automatic routing functions.	Y	1475 1474.1 1474.2
auxiliary wayside system	P	A back-up or secondary train control system, capable of providing full or partial automatic train protection for trains not equipped with trainborne communication-based train control (CBTC) equipment, and/or trains with partially or totally inoperative trainborne CBTC equipment. The auxiliary wayside system includes trainborne equipment and may also provide broken rail detection.	N	1474.1
basic operating unit	P	(A) A single vehicle designed for independent operation. (B) A permanent or semi-permanent combination, designed for independent operation, consisting of two or more vehicles of one or more types.	D	1475 1473 1474.1 1477
battery tray		The supporting structure that allows two or more individual cells, or one or more multi-cell units to be mechanically configured as one assembly.	N	1536
battery voltage	A	That voltage which is provided within specified limits by the low voltage power supply (or, in its absence, the control voltage on-board battery). Note-Battery voltage limits are specified in IEEE P1476/D4.0.	N	1475
blending	P	The combination of two or more modes of braking (e.g. rheostatic electric brake, regenerative electric brake and friction brake) to produce the desired total retarding effort.	N	1475
block	P	See IEEE Dictionary	M	1475
bonding		The establishment of a low-impedance current path between two adjacent components through an intimate interface surface.	N	16
brake, electric	P	See electric brake.
brake, emergency	P	See emergency brake.
brake, friction	P	See friction brake.
brake, “panic”	P	See “panic” brake.
brake, parking	P	See parking brake.
brake, penalty	P	See penalty brake.
brake, regenerative	P	See regenerative brake.
brake, rheostatic	P	See rheostatic brake.
brake, service (maximum)	P	See service brake (maximum).
brake, snow	P	See snow brake.
brake, straight air	P	See straight air brake.
brake, track	P	See track brake.
brakes applied	P	An indication that all friction brakes are applied to some agreed upon preset level.	N	1475
braking effort	P	That longitudinal retarding force generated by the friction brake system or the propulsion system (in electric brake).	N	1475
builder	P	The entity manufacturing the product.	N	1475 1476 1536
cab signal (system)	P	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.	Y	1475
car	P	See vehicle.	---	1475 1476 1474.1 1536
carbody		The vehicle body comprising its main load carrying structure above all suspension units. It includes all components that are connected to this structure and contribute directly to the strength, stiffness and stability. Mechanical equipment and other mounted parts are not considered part of the carbody.	N	RT-1
car builder	P	The entity assembling or manufacturing the vehicle.	N	1475 1476 1536
civil speed restriction	P	The maximum speed authorized for each section of track, as determined primarily by the alignment, profile, and structure.	Y	1474.1
closing speed		Relative speed of vehicles at instant of impact.	N	RT-1
coast	P	The mode of operation of a vehicle or train in which both tractive effort from the propulsion system and braking effort from the propulsion and friction brake systems are zero. NOTE–The inherent design characteristics of some propulsion systems will require that a negligible level of electric brake be present in the coast mode.	N	1475
cock	P	A pneumatic device having two positions, closed/shut and open/through.	N	1475
communications-based train control	P	A continuous automatic train control system utilizing: high-resolution train location determination, independent of track circuits; continuous, high capacity, bi-directional train-to-wayside data communications; and trainborne and wayside processors capable of implementing vital functions.	N	1474.1 1474.2
communications-based train control user (CBTC user)		Any authority-authorized personnel who receives information from, provides information to, or performs repair or maintenance on, a CBTC system.
commuter rail	P	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.	Y	1474.1
concept level	P	The level of verification activities at which vital functions and vital implementation requirements, imposed on the system’s design and implementation by the safety assurance concept selected, are determined and identified.	N	1483
consist	P	The makeup or composition (number and specific identity) of individuals units of a train.	D	1475 1477 1474.1
constant current loads	A	A load that demands constant current even current when the input voltage varies. Note – Typical of such loads is lighting when driven from an inverter ballast configuration.	N	1476
constant power load	A	A load that demands a constant power from the source even when the voltage value drops such as when switching from the low voltage power supply to the battery. Note – Typical of such loads that have their own built in regulator such as propulsion control voltage supply.	N	1476
continuous train control system		A locomotive or self-propelled car apparatus that is constantly in contact with wayside control apparatus and is immediately responsive to a change of conditions in the controlling section that affects train movement.	M	Not Used
controls		An active processing of commands or inputs, relaying a request to a subsystem for action.	N	1482
control action		A request by the communication based train control (CBTC) user for the CBTC system to perform an operation. A control action may require a single user input, or a sequence of user inputs, and a user requested control action may be subject to verification checks prior to the CBTC system performing the requested operation.	N	1472.2
control voltage	P	Voltage that is provided for operating the controlling elements of the train. See: battery voltage. NOTE-This may or may not be the same potential value as the battery voltage.	N	1475
coupler interface	P	That facility of an basic operating unit that is designed to provide convenient connection to, and disconnection from, any other basic operating unit without requiring disassembly of any constituent part of either basic operating unit. This includes standardized mechanical, electrical, electronic, pneumatic, and other interfaces as required.	N	1473
crashworthiness		The ability of a vehicle to manage the energy of a collision.		RT-1
corona effect		A type of localized discharge resulting from transient gaseous ionization in an insulation system, when the voltage exceeds a critical value. The ionization is usually localized over a portion of the distance between the electrodes of the system.	N	16
creepage		The shortest distance between two conducting parts measured along the surface or joints of the insulating material between them.	N	16
crush load vehicle loads (AW3)		AW1 plus 6 passengers per m^2 (5 passengers per yd^2) in standing areas, and train operator on board.	N	RT-1
crush loaded weight	P	The weight of a vehicle when loaded with crew, all seats occupied, and standees to a specified number.	N	1475
cut out	P	The state of being disabled by the conscious use of a cutout device or function.	N	1475
cutout	P	A device or function whose purpose is deliberately to disable a specified device or function, e.g. “dynamic brake cutout.”	N	1475
data recorder	P	The device used to record any type of data	N	1475
data recording	P	The act of to recording any type of data.	N	1475
deadman	P	A pressure or activity actuated alertness device to detect inattention or disability of a train operator. NOTE-The deadman can be contained within the master controller main handle grip, obtained by a separate foot switch, or obtained through an alertness type function. The device, when not properly maintained in an operational condition, will result in an emergency or full service brake application.	D	1475
dead time	P	See IEEE Dictionary.	N	1475
derail detector	P	A device so arranged as to detect a derailment condition.	N	1475
designer		The contractor who has the contractual responsibility to design, manufacture, test and certify ready for service the vehicle to satisfy the system design criteria and the vehicle specification of the Operator	N	RT-1
diagnostics		The process of determining the cause of a fault from symptoms. Active: Diagnostics based on observed conditions and commanded test routines initiated by the monitoring and diagnostic system. Passive: Diagnostics based on observed conditions.	N	1482
display		A visual representation of data, graphics or text that is presented on a screen.	N	1474.2
display screen		The surface of the display device on which the visual representation of data is presented.	N	1472.2
doors closed	P	A state, as given by trainline signal indication, in which doors are fully closed and locked.	N	1475
doors locked	P	The condition reached in the door closing cycle when the drive has achieved a latching condition that will hold doors closed mechanically until a door opening cycle is initiated.	N	1475
doors open	P	A state, as given by trainline signal indication, in which doors are not fully closed and locked.	N	1475
dwell time	P	The time a transit unit (vehicle or train) spends at a station or stop, measured as the interval between its stopping and starting.	Y	1474.1
electric brake	P	A mode of operation of the propulsion system in which retarding is provided. NOTE–Although generally considered synonymous with dynamic brake, electric brake is a more global term, in that it includes the possibility of providing retardation by drawing power from the line or other means not dependent on conversion of kinetic energy into retarding power, which is the key element of dynamic braking.	D	1475
electric coupler	P	A device used to allow trainline signals to be transmitted from vehicle to vehicle or unit to unit in a train, with the connection of trainlines performed automatically when vehicles are coupled.	D	1475
emergency brake	P	Fail-safe, open-loop braking to a complete stop with an assured maximum stopping distance considering all relevant factors. Once the brake application is initiated, it is irretrievable, i.e. it cannot be released until the train has stopped or a predetermined time has passed.	M	1475 1474.1
empty weight	P	See actual weight.
end sill compression load (buff load)		Compressive force applied at the ends of the car, usually at the anticlimber.	N	RT-1
ergonomics		The interdisplinary science which studies the relationships between people and their environment.	N	1474.2
event recorder	P	An on-board device/system with crashworthy nonvolatile memory which records data to support accident/incident analysis.	N	1475 1482 1482.1
fade	P	(A) The condition occurring during a braking cycle at low speed wherein the fundamental characteristics of the propulsion system utilized will not support the power requirement of the level of dynamic electric brake called for. Consequently, the level of dynamic electric brake actually generated decreases as a function of speed along an inherent characteristic. (B) In electric braking systems capable of supporting the level called for to zero speed, a deliberately-created characteristic wherein the level of electric brake decreases as a function of speed to allow a smooth transition to friction brake for the purpose of the final stop.	N	1475
failure		Partial or complete loss of component, subsystem or system capability, resulting in equipment being unable to perform some or all of its intended function. Note: Failures can be major, where total loss of equipment capability results, or minor, where equipment remains operable but with reduced capability or where the failure is resettable. Failures can occur in equipment which is being observed by the M&D system, termed equipment failure, or in some element of the M&D system itself, termed M&D failure. M&D failures can be further divided into two categories: monitoring failures and diagnostic failures. Monitoring failures can be divided into FRA monitoring failures, where a failure to record an FRA‑required parameter has occurred (where FRA requirements apply) or, diagnostic monitoring failures, where a failure to record a non‑FRA required parameter has occurred.	N	1482
fail-safe	P	A design philosophy applied to safety-critical systems such that the result of a hardware failure or the effect of software error shall either prohibit the system from assuming or maintaining an unsafe state, or shall cause the system to assume a state known to be safe.	Y	1475 1474.1 1483
fail-safely	P	The implementation of a function in a fail-safe manner.	N	1483
fault		A status condition outside normal or expected parameters.	N	1482
fault tree analysis (FTA)	P	A structured analysis method used to comprehensively identify faults and combinations of faults of software and hardware components as they relate to a hazard.	N	1483
forward	P	The direction of motion of the train corresponding to the direction of vision of an operator or attendant when occupying his or her normal position in a normal orientation. NOTE-For an unattended vehicle, forward may be defined by the prevailing direction of operation on the guideway segment being utilized.	N	1475
friction brake	P	The system of pneumatic, electropneumatic, hydraulic, electrohydraulic, or electric valves, controls, actuators and associated components which, in combination, provide the capability of braking the car to a stop purely by the action of friction devices upon the wheel tread, disc rotors, or other surfaces.	D	1475
full field	P	In a propulsion system, the motor connection in which, for series motors, the exciting field current is the same as the armature current, or, for separately excited motors, the exciting field current is at its maximum value.	N	1475
fully seated load vehicle load (AW1)		AWO plus full-seated passenger load and the train operator on board.	N	RT-1
function key		Assignable special purpose keys on a computer keyboard or keypad, which CBTC user employs to interact with the communications-based train control system.	N	1474.2
functional fault tree	P	A structured fault tree analysis method used to identify vital functions at the system functional level by comprehensively examining system functional faults, which could precipitate hazards.	N	1483
functional level	P	The level of verification activities at which vital system functions are identified from system functional and operational requirements.	N	1483
galvanic isolation	P	A method of electrical isolation where neither the signal nor the common of the output of the isolator is dc coupled to the signal or common of the input of the isolator, except for low level leakage associated with non-ideal components.	N	1476 1482.2
gap		The shortest distance measured through air, between parts of different potential.	N	16
grounding		The establishment of a low-impedance circuit or path to a designated ground plane or location.	N	16
hardware failure	P	A change in the characteristics of a system hardware element beyond its design tolerances.	N	1483
hazard	P	An existing or potential condition that can result in a mishap.	N	1483 1473
head end power		Train-lined auxiliary power provided from a locomotive to other cars in the train.	N	Not Used
headway	P	The time interval between the passing of the front ends of successive vehicles or trains moving along the same lane or track in the same direction.	Y	1474.1
health	P	Summary information regarding the current ability of a system or subsystem to perform its intended function.	N	1482.1 1482
heating ventilation and air conditioning (HVAC) compressor pull down	A	The condition wherein the air conditioning system in the car is turned on and is required to cool a car that has been sitting in the heat of the day. NOTE – This condition usually presents the highest/longest sustained power demands to the auxiliary inverter.	N	1476
heavy rail transit	P	A mode of rail rapid transit generally characterized by fully grade-separated construction, operating on exclusive rights of way, and station platforms at the floor level of the vehicles.	D	1475 1474.1 1476
heavy rail vehicle	P	A vehicle operating on a heavy rail transit system. Typically, electrically propelled, bi-directional, capable of operating in multiple unit, and designed for rapid, high-level boarding and discharging of passengers.	N	1475 1476
high discharge rate (H)		Typically for discharges above 3.5C5A up to 7C5A in accordance with IEC 60623.	N	1536
human computer interface		The set of stimuli that a user experiences when in and around a computer terminal including but not limited to a user interface, the work area furnishings and environmental elements consisting of bio-mechanical stresses, light, sound, temperature, and air quality.	N	1474.2
implementation level	P	The level of verification at which system components implementing vital functions are comprehensively identified and analyzed to verify that all functions identified as vital are implemented fail-safely.	N	1483
independent operation	P	The ability, when supplied with appropriate energy, and with control signals from internal sources or through one or more coupler interfaces, to perform all of the functions of which the installed equipment is intended to be capable.	N	1473
interface	A	The points where two or more physical systems or subsystems meet to transfer energy or information.	N	1476
interlocking	P	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 predefined order, thereby preventing opposing or conflicting train movements.	Y	1474.1
intermediate voltage power supply (IVPS)	A	Power supply which converts the third rail or catenary high voltage dc or ac into an intermediate voltage dc or ac to feed other power supplies.	N	1476
lay-up condition	A	Idle condition of the equipment and systems between service operations.	N	1476
light-emitting diode	P	See IEEE Dictionary.	N	1477
light rail transit	P	A mode of rail transit characterized by its ability to operate on exclusive rights-of-way, street running, center reservation running, and grade crossings and to board and discharge passengers at track or vehicle floor level.	Y	1475 1474.1 1476
light rail vehicle	P	A vehicle which operates on a light rail transit system, capable of boarding and discharging passengers at track or vehicle floor level.	Y	1475 1476
liquid crystal display	P	See IEEE Dictionary.	N	1477
load shedding	P	See IEEE Dictionary.	N	1476
load weighing	P	A function incorporated in the propulsion or friction brake system which measures changes in sprung vehicle weight. Its purpose is to permit control of tractive effort in order to achieve a constant effort-to-weight ratio for a given master control command.	N	1475
locked rotor current	P	See IEEE Dictionary.	N	1476
low discharge rate (L)		Typically for discharges up to 0.5C5A in accordance with IEC 60623.	N	1536
low voltage power supply (LVPS)	A	A power supply, which provides dc power to the low voltage devices or circuits contained on the vehicle. It can also be configured to charge the vehicle battery.	N	1476
manufacturer	A	See: builder	N	1476 1536
master control	P	The trainborne device or system directly providing the control signals to the train.	N	1475 1474.1
master controller	P	A physical device utilized by a human operator to provide the master control of a train.	N	1475
mean time between hazardous events (MTBHE)	P	Where hazardous events and the equipment, which may precipitate them are defined at the system level. The hazardous events included in MTBHE are those whose consequences are of a given severity, as determined by the organization generating the safety goals.	N	1483
Medium discharge rate (M)		Typically for discharges above 0.5C5A up to 3.5C5A in accordance with IEC 60623.	N	1536
mishap	P	An unplanned event or series of events resulting in death, injury, occupational illness, or damage to or loss of equipment or property, or damage to the environment; an accident.	N	1483
monitoring		The measurement of parameters which are then available for storage, display and/or processing.	N	1482
movement authority	P	The authority for a train to enter and travel trough a specific section of track, in a given direction. Movement authorities are assigned, supervised, and enforced by a communications-based train control system to maintain safe train separation, and to provide protection through interlockings.	N	1474.1
multi-cell unit		Two or more battery cells permanently connected.	N	1536
multiple unit	P	A system of simultaneous control of all vehicles in a consist from one master control through the means of trainlines.	D	1475
network communication timing	P	See IEEE Dictionary.	N	1475
no motion	P	A safety-critical function utilized to indicate that the train is at zero speed or sufficiently close to zero speed. Used to inhibit the ability of the doors to open when the train is moving, and can be used for functions such as emergency brake reset, that may require an indication of the no motion condition.	N	1475
operational status		Summary information regarding the current ability of a system or subsystem to perform its intended function.	N	Not Used
operator		The organization which establishes the rail transit system design criteria and technical requirements for the vehicle it intends to operate on its system.	N	RT-1
“panic” brake	P	Using any available form of braking, whether or not fail-safe, to obtain the shortest possible stopping distance.	N	1475
parallel	P	In a propulsion system, the motor circuit in which the final parallel or series-parallel motor connection is achieved and the maximum voltage available per motor is applied.	N	1475
parking brake	P	A means that supplies static braking forces to maintain a vehicle or train in a no motion state.	N	1475
passenger information sign	P	A device which displays, annunciates or communicates transit trip information to passengers, also, between passengers and vehicle crew.	N	1477
passenger mass		The mass of each passenger used in the calculation of the structural loads, fully seated load (AW1) through structural load (AW4), shall be a minimum 75 kg (65 lb).	N	RT-1
penalty brake	P	A function of the automatic train protection portion of the master control system, accomplished by a safety critical full-service or emergency brake application. NOTE-Although most commonly associated with an overspeed operating condition, penalty brake initiated for a variety of reasons, depending on the vehicle design and the requirements of the authority having jurisdiction.	N	1475
penalty overspeed condition		A condition requiring the application of the penalty brake by the automatic train protection subsystem in order to assure safe train operation	N	1472.2
performance evaluation		The technical assessment of a system or system component to determine how effectively operating objectives have been achieved.	N	1482
Personal Computer Memory Card International Association		An association to standardize methods for connecting peripherals to portable computers.	N	1477
pneumatic brake pipe	P	A pressurized air line, continuous over the length of the train, used variously to indicate train integrity, provide indication of a emergency condition, equalize reservoir pressures, or propagate a brake application signal.	N	1475
power “knock out”	P	A function, derived from friction brakes being applied above a low preset level on any truck, that removes propulsion power on every vehicle in the train.	N	1475
propulsion system	P	The system of motors, drive mechanisms, controls, and other devices that propels or retards a vehicle.	M	1475
purchaser	P	The entity which contractually acts as the customer.	N	1475
reaction time	P	See IEEE Dictionary.	N	1475
ready to run load vehicle loads (AW0)		The mass of vehicle ready to run with all mounted components including full operating reserves of windshield fluid, sand, etc., and the mass of the train operator but without any passenger load.	N	RT-1
redundancy	P	The existence in a system of more than one means of accomplishing a given function.	Y	1475 1474.1
regenerative brake	P	A form of dynamic brake in which the electrical energy generated by braking is returned to the power supply line, provided to on-board loads, or a combination thereof during the braking cycle instead of being dissipated in resistors.	M	1475
rheostatic brake	P	A form of dynamic brake in which the electrical energy generated by braking is dissipated as heat in on-board resistors during the braking cycle.	N	1475
reliability	P	The probability that a system will perform its intended functions without failure, within design parameters, under specific operating conditions, and for a specific period of time. NOTE-The ambient environmental conditions for operation are specified by the authority having jurisdiction, or, in the absence of such specifications, by IEEE P1478/D4.0.	M	1475 1474.1
remanufactured (vehicle)		A vehicle that, in order to extend its service life, has been structurally restored and had installed new or remanufactured components totaling a cost of 60% or more of then-prevailing vehicle replacement costs. NOTE-The act of rebuilding or remanufacturing is to be interpreted as a major rehabilitation, tantamount, in certain regulatory contexts, to building anew. It should not be confused with overhaul, which is to be interpreted as a scheduled maintenance action implicit in the defined service life of the vehicle.		Not Used
resistive loads	A	Loads for which the current supplied by the low voltage power supply/battery varies proportionally to the source voltage. NOTE – These loads will demand less current when the source voltage is switched from the low voltage power supply to the battery. Typically, relays fall into this category.	N	1476
response time	P	See IEEE Dictionary.	N	1475
reverse	P	The direction of operation which is opposite to forward.	N	1475
reverser	A	(A) The portion of the master controller used to change the commanded direction of train movement. (B) A circuit device used to change motor connections in order to change the direction of motor rotation and thus train movement.	N	1475
safe	P	Having acceptable risk of the occurrence of a hazard.	N	1483
safe braking model	P	An analytical representation of a train’s performance while decelerating to a complete stop, allowing for a combination of worst-case influencing factors and failure scenarios. A communication-based train control equipped train will stop in a distance equal to or less than that guaranteed by the safe braking model.	N	1474.1
safety		Freedom from those conditions that can cause death, injury, occupational illness, or damage to or loss of equipment or property, or damage to the environment.	N	Not Used
safety assurance		A characteristic of the implementation of a system which assures a level of safe operation.	N	1483
safety assurance concept	P	A design concept applied to processor-based systems which assures the fail-safe implementation of identified functions, including safe operation in the presence of hardware failures and/or software errors. Examples are: Checked Redundancy; Diversity and Self-Checking; Numerical Assurance; and N-Version Programming.	N	1483
safety critical	P	A term applied to a system or function, the correct performance of which is critical to safety of personnel and/or equipment. A term applied to a system of function, the incorrect performance of which may result in an unacceptable risk of a hazard. See also: fail-safe. NOTE-A safety-critical designation may require the incorporation of additional special safety design features. NOTE-Vital functions are a subset of safety-critical functions.	N	1475 1474.1 1483 1473
safety validation	P	A structured and managed set of activities which demonstrate that the system, as specified and implemented, performs the intended functions and that those functions result in overall safe operation. Validation answers the question, “Did we build the right system?”	N	1483
safety verification	P	A structured and managed set of activities which identify the vital functions required to be performed by the system, and demonstrate that the system, including its subsystems, interfaces and components, implements the vital functions fail-safely to a level that meets the allocated system safety goals. Verification answers the question, “Did we build the system right?”	N	1483
sampling rate	P	The frequency with which the event recorder regularly monitors an input channel to determine its value.	N	1482.1
sanding	P	Dropping or blowing of sand or similar material on the top of the rail head to increase the coefficient of friction to obtain better adhesion.	N	1475
screen		The total, full physical viewing area of display monitors.	N	1474.2
self-revealing component failures	P	Component failures whose effects on system operation are immediately and clearly apparent to a properly trained person.	N	1483
series	P	In a propulsion system, the motor connection in which all motors are connected in series for the purpose of supplying them with some fraction (usually one-half) of the available voltage..	N	1475
service	P	The operation of the vehicles under normal conditions with or without revenue passengers.	D	1475
service braking (maximum)	P	A nonemergency brake application that obtains the (maximum) brake rate that is consistent with the design of the brake system, retrievable under the control of master control.	M	1475 1474.1
service revenue	P	Transit service excluding deadheading or layovers. Any service scheduled for passenger trips.	Y	1474.1
short-time operating voltage		A supply voltage, operation at which for a defined period of time will not damage the apparatus.	N	16
slide, wheel	P	See wheel slide.
slip, wheel	P	See wheel slip.
snow brake	P	A constant application of light friction brake intended to create enough heat to mitigate the buildup of snow and ice which would interfere with the brake actuators.	N	1475
software error	P	A error in a system software element which, when executed, results in unintended system operation.	N	1483
spin, wheel	P	See wheel spin.
state of charge factor	A	Actual capacity of a battery expressed as a percentage of a fully charged. NOTE – This is based on experience, application (cycling/float service), and charging parameters.	N	1476
status		The condition or state of a system, component, or parameter at a particular time.	N	1482
step signal	P	See IEEE Dictionary.	N	1475
storage rate	P	The frequency with which sampled signals are recorded in crashworthy non-volatile memory. The event recorder may store any signal less often than it samples.	N	1482.1
straight air brake	P	An arrangement of brakes whereby air is admitted from the main reservoir through a brake valve to the straight air pipe to the brake cylinders in the operating unit. NOTE-In most rail transit vehicle applications, an electro-pneumatic overlay is utilized to assist in the straight air brake command transmission.	N	1475
straight air pipe	P	A method of transmitting a pneumatic command from the active cab to the straight air brake equipment on each vehicle in the operating unit.	N	1475
stroke width	P	In character recognition, the distance between two stroke edges, measured perpendicular to the stroke centerline.	N	1477
structural energy absorption zone		Section of carbody where controlled deformation is allowed while the integrity of the remaining carbody is maintained. This zone is usually at the ends of the carbody.	N	RT-1
structural load vehicle loads (AW4)		AW1 plus 8 passengers per m^2 (6.7 passengers per yd^2) in standing areas, and train operator on board..	N	RT-1
subsystem	P	See IEEE Dictionary.	N	1475 1482
supplier	P	The entity which contractually acts as the source of a product. NOTE-The supplier may or may not be the actual builder.	N	1475 1476 1536
“switch” (position)	P	In a propulsion system, the historic name for the lowest level of positive tractive effort and power; so called because it is typically utilized for slow-speed switching movements such as yard moves, train makeup, etc.	N	1475
system	P	See IEEE Dictionary (19).	N	1482
system load vehicle loads (AW2)		AW1 plus 4 passengers per m^2 (3.3 passengers per yd^2) in standing areas, and train operator on board..	N	RT-1
system safety	P	The application of engineering and management principles, criteria, and techniques to optimize all aspects of safety within the constraints of operational effectiveness, time, and cost throughout all phases of the system life cycle.	N	1483 1474.1
system safety goals - qualitative		A qualitative expression of the level of fail-safety which shall be achieved by a system, expressed in terms which can be realistically compared to the results of the safety verification process.	N	Not Used
system safety goals - quantitative	P	A quantitative limit of the probability and/or frequency with which any vital function fails to be implemented safely.	N	1483
system safety program	P	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 the system life cycle.	N	1483 1474.1
system safety program plan	P	A formal document that fully describes the planned safety tasks required to meet the system requirements, including organizational responsibilities, methods of accomplishment, milestones, depth of effort, and integration with other program engineering and management functions.	N	1483
time constant	P	See IEEE Dictionary.	N	1475
time critical	P	Applications where the communications delay is bound to a fixed upper limit, independent from the load conditions.	N	1473
time, dead	P	See dead time.	N	1475
time, reaction	P	See reaction time.	N	1475
time, warm-up	P	See warm-up time.	N	1475
topology	P	The geometric pattern or configuration of intelligent devices and how they are linked together for communications.	N	1473
track brake	P	A magnetic friction brake that compresses against the running rail and is activated by an electrical signal.	D	1475
traction system	P	See: propulsion system.		1475
tractive effort	P	That force generated at the wheel-rail interface as a result of the action of the propulsion system. It may be either positive, indicating motoring/powering, or negative, indicating brake.	D	1475
train	P	A consist of one or more basic operating units.	D	1475 1473 1477 1474.1
train control system	P	The system for controlling train movement, enforcing train safety, and directing train operations.	N	1477
trainline(s)	P	Wires and/or pipes routed though and between vehicles or units by means of couplers, jumpers, or other means so that power or signals may be transmitted to all vehicles of the train.	N	1475
trainline interoperability	P	The ability of basic operating units that constitute a train to communicate successfully with each other through coupler interface(s), without limitation as to the sequence or orientation of the basic operating units within the train, and without requirement for manual configuration other than optional manual confirmation of basic operating unit sequence within the train.	N	1473
transport time	P	See IEEE Dictionary.	N	1475
trip switch/cock	P	A device mounted on the truck of a vehicle, responding to a raised arm on the wayside, used to cause an emergency brake application if a train attempts to pass a mandatory stop signal.	N	1475
truck	P	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. If powered, it may also contain traction motors and associated drive mechanisms.	Y	1475
unit	P	See: basic operating unit.	Y	1475 1473 1474.1
unsafe	P	Having unacceptable risk of the occurrence of a hazard.	N	1483
user interface		That portion of the human-computer interface in which the communication based train control (CBTC) user interacts with the CBTC system to observe/or perform functions implemented by the CBTC system.. Includes, but not limited to, displays, audible indicators, tactile entries, cursor positioning device implementations, voice input devices.	N	1474.2
user profile		A definition of the audio, visual, language and physical characteristics of the communication based train control user.
vehicle	P	A land conveyance assembly for carrying or transporting people or objects, capable of traversing a guideway, having structural integrity and general mechanical completeness but not necessarily designed for independent operation.	Y	1475 1473 1474.1 1477 1476 1536
vehicle mass		The mass of vehicle ready to run, consisting of the completely assembled body with all mounted components, including full operating reserves of windshield fluid, sand, etc., and the weight of the operator, but without any passenger load. Classified as AW0.	N	RT-1
vital	P	See: safety critical	N	1473
vital function	P	A function in a safety critical system, which is required to be implemented in a fail-safe manner. Note – Vital functions are a subset of safety-critical functions.	N	1483 1474.1
warm-up time	P	See IEEE Dictionary.	N	1475
weak field	P	In a propulsion system, a motor connection or operating mode in which the exciting field current is less than the full field value.	N	1475
weight, actual	P	See actual weight.
weight, crush loaded	P	See crushed loaded weight.
weight, empty	P	See actual weight.
wheel diameter compensation	P	A function which corrects for either the wear of the wheel(s) or the difference(s) in rolling diameter between different wheels on the vehicle or both.	N	1475
wheel slide	P	During braking, the condition existing when the rotational speed of the wheel is slower than that for pure rolling contact between tread and rail/running surface. Note – For convenience and simplicity, the definition of wheel slide, wheel slip, and wheel spin ignore the presence of the microslip phenomenon generally called “creep” physically necessary to generate longitudinal force at the wheel-rail interface.	N	1475
wheel slip	P	The condition existing when the rotational speed of the wheel does not correspond with pure rolling contact between tread and rail/running surface. Note – For convenience and simplicity, the definition of wheel slide, wheel slip, and wheel spin ignore the presence of the microslip phenomenon generally called “creep” physically necessary to generate longitudinal force at the wheel-rail interface.	N	1475
wheel spin		During acceleration, the condition existing when the rotational speed of the wheel is faster than that for pure rolling contact between tread and rail/running surfaces. Note – For convenience and simplicity, the definition of wheel slide, wheel slip, and wheel spin ignore the presence of the microslip phenomenon generally called “creep” physically necessary to generate longitudinal force at the wheel-rail interface.	N	1475
window		In a graphical user interface, a defined portion of the display screen that is separated by a from from the rest of the screen and which may be opened, closed, resized and moved by the user.	N	1474.2

REFERENCE STANDARDS

The information contained in this listing is based upon the standard drafts as listed below:

WG	No.	Draft	Date.	Description
	ASME
	RT-1	D3	09/25/00	Structural Requirements for Light Rail Transit Vehicles
	RT-2			Structural Requirements for Heavy Rail Transit Vehicles
	IEEE
1	1473	1999		Communication Protocol on Trains
2	1474.1	1999		Communications-Based Train Control (CBTC) Performance and Functional Requirements
2A	P1474.2	D2.0	10/00	User Interface Requirements in Communications Based Train Control (CBTC ) Systems
2B				CBTC Wayside Environmental Requirements
3	P1482	D699	06/99	Rail Vehicle Monitoring and Diagnostic Systems
3A	1482.1	1999		Rail Transit Vehicle Event Recorders
4	1483	2000		Verification of Vital Functions in Processor-Based Systems Used in Rail Transit Control
5	1475	1999		Functioning of and Interfaces among Propulsion, Friction Brake and Train-borne Master Control on Rail Transit Vehicle
6	1476	2000		Passenger Train Vehicle Auxiliary Power Systems Interfaces
7	1477	1998		Passenger Information System for Rail Transit Vehicles
8	P1478	D9.0	07/12/00	Environmental Conditions for Rail Transit Car Electronic Equipment
9	P1544			Transit Communications Interface Profiles for Rail Transit Systems
10	P1536		03/01/00	Rail Transit Vehicle Battery Physical Interface
11	P16	D1.4	06/21/00	Electrical and Electronic Control Apparatus on Rail Vehicles
12	P1558			Software Documentation
13	P1536	D2.0	02/01	Electrical Sizing of NiCad Batteries
14	P1570	D1.0	07/00	The Interface Between the Rail Subsystem and the Highway Subsystem at a Highway Rail Interface

Note: P indicates proposed standard. Standards that are issued do not contain the P prior to the number.

Revisions

Version 1: May 8, 1998

Version 2: May 28, 1998

Added version numbers to this document.

The following definitions were modified: adhesion, basic operating unit, braking effort, consist, control voltage, derail detector, electric coupler, emergency brake, fade, load weighing, master control, no motion, parking brake, safety critical, train, trainlines(s), wheel slide, track brake, unit, wheel slip, and wheel spin.

These changes are based upon P1475 D 4.1.

Version 3 June 8, 1998

Added health for P1482.1

Version 4 June 17, 1998

Includes abbreviations and added other document usage to the definition table.

Added definitions for manufacturer.

Modified the FRA Event Recorder to FRA Compliant Event Recorder.

Version 5 September 11, 1998

Abbreviations were added for AWG, ML, MTBE, MTBF, PD, PV and TCRP.

Definitions were added for doors closed, doors locked, headway, manufacturer, movement authority and topology.

Definitions were revised for apparatus interoperability, basic operating unit, brake – emergency, brake – track, consist, control voltage, coupler interface, doors open, load weighing, parallel, safety critical, series, topology, and weight – actual.

Version 6 September 17, 1998

Abbreviations were added for EMC, HEP, LVPS, and NEMA.

Abbreviation usage added for ANSI in 1476.

Definitions were added for aging factor, constant power load, HVAC compressor pull down, rebuilt, remanufactured, resistive load, sampling rate, state of charge, and storage rate.

Definition usage deleted for failure in 1482.1.

Definition usage added for authority having jurisdiction and vehicle in 1476

Version 7 October 3, 1998

Definition for automatic train supervision was revised to include a note.

Version 8 November 3, 1998

Corrected abbreviations for FRA and FTA.

Definition for block was changed to use the IEEE Dictionary.

The definition of safety critical was changed based on the recirculation ballot.

Version 9 December 1, 1998

Added definitions the mean time between hazardous events and self-revealing component failures.

Revised definitions for hardware failure, mishap, safe, safety critical, software error and unsafe.

These changes were based upon P1483 version D0.14.

Version 10 January 22, 1999

Corrected abbreviation for IEC and location of NFPA abbreviation.

Added definitions for aging factor (previous IEEE Dictionary), constant current loads and interface (previously IEEE Dictionary).

Revised definitions for constant power loads, HVAC compressor pull down, lay-up condition and resistive loads.

Version 11 June 8,1999

Added abbreviations for AAR, ASCE, CENELEC, EMI, FMEA, ITE, MTTR, MTTRS, NOAA, RF, SAE, SSHIA, SSn-FTA, SVP and UL.

Added status column to definition section.

Added definitions for buff load, carbody, closing speed, crashworthiness, crush load, designer, energy absorption load, operator, primary injury, safe braking model, seated load, secondary injury, system design load, vital and vehicle mass.

Updated definitions for auxiliary wayside system, communication-based train control, concept level, coupler interface, fail-safe, fault tree analysis, functional fault tree, functional level, heavy rail transit, implementation level, mean time between hazardous events, movement authority, safe braking model, safety critical, time critical and trainline interoperability.

Added additional usage to ATO and time critical.

Added a table to define the classes associated with 1478 environmental Standards for Rail Transit Equipment.

Added ASME RT1 standard to table to indicate the agreed upon joint usage of definitions between the two organizations.

Added working groups 9 through 12 to Reference Standards Table.

Version 12 July 2, 1999

Corrected abbreviation for IEC.

Added abbreviation for IVPS.

Added definitions for galvanic isolation, intermediate voltage power supply (IVPS), load shedding and low voltage power supply (LVPS).

Corrected definitions for aging factor, constant current loads, constant power loads, and heating ventilation and air conditioning(HVAC) compressor pull down.

Updated revision level for standard P1476.

Version 13 July 15, 1999

Corrected definition for functional fault tree.

Updated revision level for standard P1483.

Version 14 October 14, 1999

Modified definitions for carbody, crashworthiness, end sill compression (buff load) and system design load.

Buff load was changed to end sill compression (buff load).

Deleted designer and operator.

Version 15 January 7, 2000

Added abbreviation for BC.

Corrected abbreviation for TRCP.

Corrected definitions for aging factor, constant power load, galvanic isolation, intermediate voltage power supply and resistive loads.

Updated revision levels for various reference standards.

Version 16 November 27, 2000

Added abbreviations for AASHTO, ACSES, APTA, AREMA, GPS, GUI, ITS, MDS and NTCIP.

The definition status was revised to include published indicated by the letter “P”. Published means accepted by the standard’s editors.

Definitions were revised to agree with the final wording and format used by the standard’s editors.

Definitions were revised to agree with the latest drafts of the standards as listed in the reference standards table.

Added definitions for ambient temperature, bonding, corona effect, creepage, designer, display, ergonomics, function key, gap, grounding, passenger mass, screen, user interface and window.

Deleted definitions for FRA compliant event recorder, primary injury, rebuilt and secondary injury.

Deleted the 1478 class definition table, as the classifications were not used in the final standard.

Version 17 December 6, 2000

Corrected abbreviation for APTA.

Version 18 February 13, 2001

Added abbreviations for ampere hours.

Added definitions for high discharge rate, low discharge rate, medium discharge rate, and multi-cell unit.

Added usage of 1536 to abbreviations and definitions.

Added 1536 revision level to reference standards table.

Version 19 April 12, 2002

Added definitions for communication based train control user, control action, display screen, function key, penalty overspeed condition, short-time operating voltage and user profile.

Modified definitions for display, user interface and windows.

Added ASME RT-2 standard to reference standard table.

Corrected Software Documentation working group number form P1588 to P1558.

definitions.doc