[Code of Federal Regulations]

[Title 49, Volume 4]

[Revised as of October 1, 2005]

From the U.S. Government Printing Office via GPO Access

[CITE: 49CFR238.5]



[Page 644-652]

 

                        TITLE 49--TRANSPORTATION

 

       CHAPTER II--FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF 

                             TRANSPORTATION

 

PART 238_PASSENGER EQUIPMENT SAFETY STANDARDS--Table of Contents

 

                            Subpart A_General

 

Sec. 238.5  Definitions.



    As used in this part--

    AAR means the Association of American Railroads.

    APTA means the American Public Transit Association.

    Actuator means a device directly actuated by the movement of the 

brake cylinder piston which provides an indication of the piston travel.

    Administrator means the Administrator of the Federal Railroad 

Administration or the Administrator's delegate.

    Alerter means a device or system installed in the locomotive cab to 

promote continuous, active locomotive engineer attentiveness by 

monitoring select locomotive engineer-induced control activities. If 

fluctuation of a monitored locomotive engineer-induced control activity 

is not detected within a predetermined time, a sequence of audible and 

visual alarms is activated so as to progressively prompt a response by 

the locomotive engineer. Failure by the locomotive engineer to institute 

a change of state in a monitored control, or acknowledge the alerter 

alarm activity through a manual reset provision, results in a penalty 

brake application that brings the locomotive or train to a stop.

    Anti-climbing mechanism means the parts at the ends of adjoining 

vehicles in a train that are designed to engage when subjected to large 

buff loads to prevent the override of one vehicle by another.

    Bind means restrict the intended movement of one or more brake 

system components by obstruction, increased friction, or reduced 

clearance.

    Block of cars means one car or multiple cars in a solid unit coupled 

together for the purpose of being added to, or removed from, a train as 

a solid unit.

    Brake, air or power brake means a combination of devices operated by 

compressed air, arranged in a system, and controlled manually, 

electrically, or pneumatically, by means of which the motion of a rail 

car or locomotive is retarded or arrested.

    Brake, disc means a retardation system used on some rail vehicles, 

primarily passenger equipment, that utilizes flat metal discs as the 

braking surface instead of the wheel tread.

    Brake, dynamic means a train braking system whereby the kinetic 

energy of a moving train is used to generate electric current at the 

locomotive traction motors, which is then dissipated through banks of 

resistor grids or back into the catenary or third rail system.

    Brake, effective means a brake that is capable of producing its 

required designed retarding force on the train. A brake is not effective 

if its piston travel is in excess of the maximum prescribed limits. On 

vehicles equipped with nominal 12-inch stroke brake cylinders, the brake 

is not effective if its piston travel exceeds 10\1/2\ inches.

    Brake indicator means a device, actuated by brake cylinder pressure, 

which indicates whether brakes are applied or released.

    Brake, inoperative means a primary brake that, for any reason, no 

longer applies or releases as intended or is otherwise ineffective.

    Brake, on-tread friction means a braking system that uses a brake 

shoe that



[[Page 645]]



acts on the tread of the wheel to retard the vehicle.

    Brake, parking or hand brake means a brake that can be applied and 

released by hand to prevent movement of a stationary rail car or 

locomotive.

    Brake pipe means the system of piping (including branch pipes, angle 

cocks, cutout cocks, dirt collectors, hoses, and hose couplings) used 

for connecting locomotives and all rail cars for the passage of air to 

control the locomotive and car brakes.

    Brake, power means ``air brake'' as that term is defined in this 

section.

    Brake, primary means those components of the train brake system 

necessary to stop the train within the signal spacing distance without 

thermal damage to friction braking surfaces.

    Brake, secondary means those components of the train brake system 

which develop supplemental brake retarding force that is not needed to 

stop the train within signal spacing distances or to prevent thermal 

damage to friction braking surfaces.

    Brake shoes or pads aligned with tread or disc means that the 

surface of the brake shoe or pad, respectively, engages the surface of 

the wheel tread or disc, respectively, to prevent localized thermal 

stress.

    Braking system, blended means a braking system where the primary 

brake and one or more secondary brakes are automatically combined to 

stop the train. If the secondary brakes are unavailable, the blended 

brake uses the primary brake alone to stop the train.

    Calendar day means a time period running from one midnight to the 

next midnight on a given date.

    Class I brake test means a complete passenger train brake system 

test and inspection (as further specified in Sec. 238.313) performed by 

a qualified maintenance person to ensure that the air brake system is 

100 percent effective.

    Class IA brake test means a test and inspection (as further 

specified in Sec. 238.315) performed by a qualified person of the air 

brake system on each car in a passenger train to ensure that the brakes 

apply and release on each car in the train in response to train line 

commands.

    Class II brake test means a test and inspection (as further 

specified in Sec. 238.317) performed by a qualified person of brake 

pipe integrity and continuity from the controlling locomotive to the 

rear unit of a passenger train.

    Collision posts means structural members of the end structures of a 

vehicle that extend vertically from the underframe to which they are 

securely attached and that provide protection to occupied compartments 

from an object penetrating the vehicle during a collision.

    Control valves means that part of the air brake equipment on each 

rail car or locomotive that controls the charging, application, and 

release of the air brakes, in response to train line commands.

    Corner posts means structural members located at the intersection of 

the front or rear surface with the side surface of a rail vehicle and 

which extend vertically from the underframe to the roof. Corner posts 

may be combined with collision posts to become part of the end 

structure.

    Crack means a fracture without complete separation into parts, 

except that, in a casting, a shrinkage crack or hot tear that does not 

significantly diminish the strength of the member is not a crack.

    Crash energy management means an approach to the design of rail 

passenger equipment which controls the dissipation of energy during a 

collision to protect the occupied volumes from crushing and to limit the 

decelerations on passengers and crewmembers in those volumes. This may 

be accomplished by designing energy-absorbing structures of low strength 

in the unoccupied volumes of a rail vehicle or passenger train to 

collapse in a controlled manner, while providing higher structural 

strength in the occupied volumes. Energy deflection can also be part of 

a crash energy management approach. Crash energy management can be used 

to help provide anti-climbing resistance and to reduce the risk of train 

buckling during a collision.

    Crash refuge means a volume with structural strength designed to 

maximize the survivability of crewmembers



[[Page 646]]



stationed in the locomotive cab during a collision.

    Crewmember means a railroad employee called to perform service 

covered by the Federal hours of service laws at 49 U.S.C. 21103 and 

subject to the railroad's operating rules and program of operational 

tests and inspections required in Sec. 217.9 and Sec. 217.11 of this 

chapter.

    Critical buckling stress means the minimum stress necessary to 

initiate buckling of a structural member.

    Emergency brake application means an irretrievable brake application 

resulting in the maximum retarding force available from the train brake 

system.

    Emergency window means that segment of a side-facing glazing panel 

which has been designed to permit rapid and easy removal in an emergency 

situation.

    End structure means the main support structure projecting upward 

from the underframe of a locomotive, passenger car, or other rail 

vehicle. The end structure is securely attached to the underframe at 

each end of a rail vehicle.

    50th-percentile adult male means a person weighing 164 pounds (plus 

or minus 3 pounds) and possessing the following dimensions: erect 

sitting height: 35.7 inches (plus or minus 0.1 inch); hip breadth 

(sitting): 14.7 inches (plus or minus 0.7 inch); hip circumference 

(sitting): 42 inches; waist circumference (sitting): 32 inches (plus or 

minus 0.6 inch); chest depth: 9.3 inches (plus or minus 0.2 inch); and 

chest circumference: 37.4 inches (plus or minus 0.6 inch).

    Foul means restrict the intended movement of one or more brake 

system components because the component is snagged, entangled, or 

twisted.

    FRA means the Federal Railroad Administration.

    Fuel tank, external means a fuel containment volume that extends 

outside the car body structure of a locomotive.

    Fuel tank, internal means a fuel containment volume that does not 

extend outside the car body structure of a locomotive.

    Full-height collision post, corner post, or side frame post means 

any vertical framing member in the rail car body structure that spans 

the distance between the underframe and the roof at the car body section 

where the post is located. For collision posts located at the 

approximate third points laterally of an end frame, the term ``full-

height'' applies to posts that extend and connect to supporting 

structural members in the roof at the location of the posts, or to a 

beam connected to the top of the end-frame and supported by the roof 

rails (or anti-telescoping plate), or to both.

    Full service application means a brake application which results in 

a brake cylinder pressure at the service limiting valve setting or 

equivalent.

    Glazing, end-facing means a glazing panel located where a line 

perpendicular to the exterior surface of the panel makes an angle of 50 

degrees or less with the longitudinal center line of the rail vehicle in 

which the panel is installed. A glazing panel that curves so as to meet 

the definition for both side-facing and end-facing glazing is considered 

end-facing glazing.

    Glazing, exterior means a glazing panel that is an integral part of 

the exterior skin of a rail vehicle and has a surface exposed to the 

outside environment.

    Glazing, side-facing means a glazing panel located where a line 

perpendicular to the exterior surface of the panel makes an angle of 

more than 50 degrees with the longitudinal center line of the rail 

vehicle in which the panel is installed.

    Handrails means safety appliances installed on either side of a rail 

vehicle's exterior doors to assist passengers and crewmembers to safely 

board and depart the vehicle.

    Head end power means power generated on board the locomotive of a 

passenger train used for purposes other than propelling the train, such 

as cooking, heating, illumination, ventilation and air conditioning.

    In passenger service/in revenue service means a train or passenger 

equipment that is carrying, or available to carry, passengers. 

Passengers need not have paid a fare in order for the equipment to be 

considered in passenger or in revenue service.

    In service, when used in connection with passenger equipment, means:



[[Page 647]]



    (1) Passenger equipment subject to this part that is in passenger or 

revenue service in the United States; and

    (2) All other passenger equipment subject to this part in the United 

States, unless the passenger equipment:

    (i) Is being handled in accordance with Sec. Sec. 238.15, 238.17, 

238.305(d), or 238.503(f), as applicable;

    (ii) Is in a repair shop or on a repair track;

    (iii) Is on a storage track and is not carrying passengers; or

    (iv) Has been delivered in interchange but has not been accepted by 

the receiving railroad.

    Interior fitting means any component in the passenger compartment 

which is mounted to the floor, ceiling, sidewalls, or end walls and 

projects into the passenger compartment more than 25 mm (1 in.) from the 

surface or surfaces to which it is mounted. Interior fittings do not 

include side and end walls, floors, door pockets, or ceiling lining 

materials, for example.

    Lateral means the horizontal direction perpendicular to the 

direction of travel.

    Locomotive means a piece of on-track rail equipment, other than hi-

rail, specialized maintenance, or other similar equipment, which may 

consist of one or more units operated from a single control stand with 

one or more propelling motors designed for moving other passenger 

equipment; with one or more propelling motors designed to transport 

freight or passenger traffic, or both; or without propelling motors but 

with one or more control stands. This term does not include a locomotive 

propelled by steam power unless it is used to haul an intercity or 

commuter passenger train. Nor does this term include a freight 

locomotive when used to haul a passenger train due to failure of a 

passenger locomotive.

    Locomotive cab means the compartment or space on board a locomotive 

where the control stand is located and which is normally occupied by the 

engineer when the locomotive is operated.

    Locomotive, cab car means rail rolling equipment intended to provide 

transportation for members of the general public that is without 

propelling motors but equipped with one or more control stands.

    Locomotive, controlling means the locomotive from which the 

locomotive engineer exercises control over the train.

    Locomotive, MU means rail rolling equipment self-propelled by any 

power source and intended to provide transportation for members of the 

general public; however, this term does not include an MU locomotive 

propelled by steam power unless it is used to haul an intercity or 

commuter passenger train.

    Longitudinal means in a direction parallel to the normal direction 

of travel.

    Luminescent material means material that absorbs light energy when 

ambient levels of light are high and emits this stored energy when 

ambient levels of light are low, making the material appear to glow in 

the dark.

    L/V ratio means the ratio of the lateral force that any wheel exerts 

on an individual rail to the vertical force exerted by the same wheel on 

the rail.

    MIL-STD-882 means a military standard issued by the United States 

Department of Defense to provide uniform requirements for developing and 

implementing a system safety plan and program to identify and then 

eliminate the hazards of a system or reduce the associated risk to an 

acceptable level.

    Mph means miles per hour.

    95th-percentile adult male means, except as used in Sec. 

238.447(f)(2), a person weighing 215 pounds and possessing the following 

dimensions: erect sitting height: 38 inches; hip breadth (sitting): 16.5 

inches; hip circumference (sitting): 47.2 inches; waist circumference 

(sitting): 42.5 inches; chest depth: 10.5 inches; and chest 

circumference 44.5 inches.

    Occupied volume means the volume of a rail vehicle or passenger 

train where passengers or crewmembers are normally located during 

service operation, such as the operating cab and passenger seating and 

sleeping areas. The entire width of a vehicle's end compartment that 

contains a control stand is an occupied volume. A vestibule is typically 

not considered occupied, except when it contains a control stand for use 

as a control cab.



[[Page 648]]



    Ordered, as applied to acquisition of equipment, means that the 

acquiring entity has given a notice to proceed to manufacture the 

equipment that represents a firm financial commitment to compensate the 

manufacturer for the contract price of the equipment or for damages if 

the order is nullified. Equipment is not ordered if future exercise of a 

contract option is required to place the remanufacturing process in 

motion.

    Override means to climb over the normal coupling or side buffers and 

linking mechanism and impact the end of the adjoining rail vehicle or 

unit above the underframe.

    Passenger car means rail rolling equipment intended to provide 

transportation for members of the general public and includes a self-

propelled car designed to carry passengers, baggage, mail, or express. 

This term includes a passenger coach, cab car, and an MU locomotive. In 

the context of articulated equipment, ``passenger car'' means that 

segment of the rail rolling equipment located between two trucks. This 

term does not include a private car.

    Passenger coach means rail rolling equipment intended to provide 

transportation for members of the general public that is without 

propelling motors and without a control stand.

    Passenger equipment--means

    (1) All powered and unpowered passenger cars, locomotives used to 

haul a passenger car, and any other rail rolling equipment used in a 

train with one or more passenger cars. Passenger equipment includes--

    (i) A passenger coach,

    (ii) A cab car,

    (iii) A MU locomotive,

    (iv) A locomotive not intended to provide transportation for a 

member of the general public that is used to power a passenger train, 

and

    (v) Any non-self-propelled vehicle used in a passenger train, 

including an express car, baggage car, mail car, freight car, or a 

private car.

    (2) In the context of articulated equipment, ``passenger equipment'' 

means a segment of rail rolling equipment located between two trucks 

that is used in a train with one or more passenger cars. This term does 

not include a freight locomotive when used to haul a passenger train due 

to failure of a passenger locomotive.

    Passenger station means a location designated in a railroad's 

timetable where passengers are regularly scheduled to get on or off any 

train.

    Permanent deformation means the undergoing of a permanent change in 

shape of a structural member of a rail vehicle.

    Person means an entity of any type covered under 1 U.S.C. 1, 

including but not limited to the following: a railroad; a manager, 

supervisor, official, or other employee or agent of a railroad; any 

owner, manufacturer, lessor, or lessee of railroad equipment, track, or 

facilities; any independent contractor providing goods or services to a 

railroad; and any employee of such owner, manufacturer, lessor, lessee, 

or independent contractor.

    Piston travel means the amount of linear movement of the air brake 

hollow rod (or equivalent) or piston rod when forced outward by movement 

of the piston in the brake cylinder or actuator and limited by the brake 

shoes being forced against the wheel or disc.

    Power car means a rail vehicle that propels a Tier II passenger 

train or is the lead vehicle in a Tier II passenger train, or both.

    Pre-revenue service acceptance testing plan means a document, as 

further specified in Sec. 238.111, prepared by a railroad that explains 

in detail how pre-revenue service tests of passenger equipment 

demonstrate that the equipment meets Federal safety standards and the 

railroad's own safety requirements.

    Primary responsibility means the task that a person performs during 

at least 50 percent of the time that the person is working. The totality 

of the circumstances will be considered on a case-by-case basis in 

circumstances where an individual does not spend 50 percent of his or 

her workday engaged in any one readily identifiable type of activity. 

Time spent supervising employees engaged in the functions of 

troubleshooting, inspection, testing, maintenance, or repair of train 

brake



[[Page 649]]



and mechanical components and systems covered by this part shall be 

considered work which is generally consistent with the function of 

troubleshooting of such systems and components for the purpose of the 

definition of this term and the definition of ``Qualified Maintenance 

Person.''

    Private car means rail rolling equipment that is used only for 

excursion, recreational, or private transportation purposes. A private 

car is not a passenger car.

    Public highway-rail grade crossing means a location where a public 

highway, road or street, including associated sidewalks or pathways, 

crosses one or more active railroad tracks at grade.

    Qualified maintenance person means a qualified person who has 

received, as a part of the training, qualification, and designation 

program required under Sec. 238.109, instruction and training that 

includes ``hands-on'' experience (under appropriate supervision or 

apprenticeship) in one or more of the following functions: 

troubleshooting, inspection, testing, maintenance, or repair of the 

specific train brake and other components and systems for which the 

person is assigned responsibility. This person shall also possess a 

current understanding of what is required to properly repair and 

maintain the safety-critical brake or mechanical components for which 

the person is assigned responsibility. Further, the qualified 

maintenance person shall be a person whose primary responsibility 

includes work generally consistent with the above-referenced functions 

and is designated to:

    (1) Conduct Class I brake tests under this part;

    (2) Conduct exterior calendar day mechanical inspections on MU 

locomotives or other passenger cars and unpowered vehicles under this 

part; or

    (3) Determine whether equipment not in compliance with this part may 

be moved as required by Sec. 238.17.

    Qualified person means a person who has received, as a part of the 

training, qualification, and designation program required under Sec. 

238.109, instruction and training necessary to perform one or more 

functions required under this part. The railroad is responsible for 

determining that the person has the knowledge and skills necessary to 

perform the required function for which the person is assigned 

responsibility. The railroad determines the qualifications and 

competencies for employees designated to perform various functions in 

the manner set forth in this part. Although the rule uses the term 

``qualified person'' to describe a person responsible for performing 

various functions required under this part, a person may be deemed 

qualified to perform some functions but not qualified to perform other 

functions. For example, although a person may be deemed qualified to 

perform the Class II brake test required by this part, that same person 

may or may not be qualified to perform the Class IA brake test or 

authorize the movement of defective equipment under this part. The 

railroad will determine the required functions for which an individual 

will be deemed a ``qualified person'' based upon the instruction and 

training the individual has received pursuant to Sec. 238.109 on a 

particular function.

    Railroad means any form of nonhighway ground transportation that 

runs on rails or electromagnetic guideways and any entity providing such 

transportation, including--

    (i) Commuter or other short-haul railroad passenger service in a 

metropolitan or suburban area and commuter railroad service that was 

operated by the Consolidated Rail Corporation on January 1, 1979; and

    (ii) High speed ground transportation systems that connect 

metropolitan areas, without regard to whether those systems use new 

technologies not associated with traditional railroads; but does not 

include rapid transit operations in an urban area that are not connected 

to the general railroad system of transportation.

    Refresher training means periodic retraining required by a railroad 

for employees or contractors to remain qualified to perform specific 

equipment inspection, testing, or maintenance functions.

    Repair point means a location designated by a railroad where repairs 

of the type necessary occur on a regular basis. A repair point has, or 

should



[[Page 650]]



have, the facilities, tools, and personnel qualified to make the 

necessary repairs. A repair point need not be staffed continuously.

    Respond as intended means to produce the result that a device or 

system is designed to produce.

    Rollover strength means the strength provided to protect the 

structural integrity of a rail vehicle in the event the vehicle leaves 

the track and impacts the ground on its side or roof.

    Roof rail means the longitudinal structural member at the 

intersection of the side wall and the roof sheathing.

    Running brake test means a test (as further specified in Sec. 

238.319) performed by a qualified person of a train system or component 

while the train is in motion to verify that the system or component 

functions as intended.

    Running gear defect means any condition not in compliance with this 

part which involves a truck component, a draft system component, a 

wheel, or a wheel component.

    Safety appliance means an appliance required under 49 U.S.C. chapter 

203, excluding power brakes. The term includes automatic couplers, hand 

brakes, sill steps, handholds, handrails, or ladder treads made of steel 

or a material of equal or greater mechanical strength used by the 

traveling public or railroad employees that provide a means for safely 

coupling, uncoupling, or ascending or descending passenger equipment.

    Safety-critical means a component, system, or task that, if not 

available, defective, not functioning, not functioning correctly, not 

performed, or not performed correctly, increases the risk of damage to 

passenger equipment or injury to a passenger, crewmember, or other 

person.

    Semi-permanently coupled means coupled by means of a drawbar or 

other coupling mechanism that requires tools to perform the uncoupling 

operation. Coupling and uncoupling of each semi-permanently coupled unit 

in a train can be performed safely only while at a maintenance or shop 

location where personnel can safely get under a unit or between units.

    Semi-monocoque means a type of rail vehicle construction where the 

shell or skin acts as a single unit with the supporting frame to resist 

and transmit the loads acting on the rail vehicle.

    Shear strength means the ability of a structural member to resist 

forces or components of forces acting perpendicular to compression or 

tension forces, or both, in the member.

    Shock absorbent material means material designed to prevent or 

mitigate injuries due to impact by yielding and absorbing much of the 

energy of impact.

    Side posts means main vertical structural elements in the sides of a 

rail vehicle.

    Side sill means that portion of the underframe or side at the bottom 

of the rail vehicle side wall.

    Single car test means a comprehensive test (as further specified in 

Sec. 238.311) of the functioning of all critical brake system 

components installed on an individual passenger car or unpowered 

vehicle, other than a self-propelled passenger car, used or allowed to 

be used in a passenger train.

    Single car test device means a device capable of controlling the 

application and release of the brakes on an individual passenger car or 

an unpowered vehicle, other than a self-propelled passenger car, through 

pneumatic or electrical means.

    Skin means the outer covering of a fuel tank and a rail vehicle. The 

skin may be covered with another coating of material such as fiberglass.

    Spall, glazing means small pieces of glazing that fly off the back 

surface of the glazing when an object strikes the front surface.

    Switching service means the classification of freight cars according 

to commodity or destination; assembling of cars for train movements; 

changing the position of cars for purposes of loading, unloading, or 

weighing; placing of locomotives and cars for repair or storage; or 

moving of rail equipment in connection with work service that does not 

constitute a train movement.

    Telescope means override an adjoining rail vehicle or unit and 

penetrate into the interior of that adjoining vehicle or unit because of 

compressive forces.

    Terminal means a starting point or ending point of a single 

scheduled trip for a train, where passengers may get



[[Page 651]]



on or off a train. Normally, this location is a point where the train 

would reverse direction or change destinations.

    Tier I means operating at speeds not exceeding 125 mph.

    Tier II means operating at speeds exceeding 125 mph but not 

exceeding 150 mph.

    Tourist, scenic, historic, or excursion operations means railroad 

operations that carry passengers, often using antiquated equipment, with 

the conveyance of the passengers to a particular destination not being 

the principal purpose. Train movements of new passenger equipment for 

demonstration purposes are not tourist, scenic, historic, or excursion 

operations.

    Trailer car means a rail vehicle that neither propels a Tier II 

passenger train nor is the leading unit in a Tier II passenger train. A 

trailer car is normally without a control stand and is normally occupied 

by passengers.

    Train means a locomotive unit or locomotive units coupled, with or 

without cars. For the purposes of the provisions of this part related to 

power brakes, the term ``train'' does not include such equipment when 

being used in switching service.

    Train brake communication line means the communication link between 

the locomotive and passenger equipment in a train by which the brake 

commands are transmitted. This may be a pneumatic pipe, electrical line, 

or radio signal.

    Train, commuter means a passenger train providing commuter service 

within an urban, suburban, or metropolitan area. The term includes a 

passenger train provided by an instrumentality of a State or a political 

subdivision of a State.

    Train, long-distance intercity passenger means a passenger train 

that provides service between large cities more than 125 miles apart and 

is not operated exclusively in the National Railroad Passenger 

Corporation's Northeast Corridor.

    Train, passenger means a train that transports or is available to 

transport members of the general public. If a train is composed of a 

mixture of passenger and freight equipment, that train is a passenger 

train for purposes of this part.

    Train, short-distance intercity passenger means a passenger train 

that provides service exclusively on the National Railroad Passenger 

Corporation's Northeast Corridor or between cities that are not more 

than 125 miles apart.

    Train, Tier II passenger means a short-distance or long-distance 

intercity passenger train providing service at speeds that include those 

exceeding 125 mph but not exceeding 150 mph.

    Trainset, passenger means a passenger train.

    Transverse means in a direction perpendicular to the normal 

direction of travel.

    Ultimate strength means the load at which a structural member 

fractures or ceases to resist any load.

    Uncoupling mechanism means the arrangement for operating the coupler 

by any means.

    Underframe means the lower horizontal support structure of a rail 

vehicle.

    Unit means passenger equipment of any type, except a freight 

locomotive when used to haul a passenger train due to failure of a 

passenger locomotive.

    Unoccupied volume means the volume of a rail vehicle or passenger 

train which does not contain seating and is not normally occupied by 

passengers or crewmembers.

    Vehicle, rail means passenger equipment of any type and includes a 

car, trailer car, locomotive, power car, tender, or similar vehicle. 

This term does not include a freight locomotive when used to haul a 

passenger train due to failure of a passenger locomotive.

    Vestibule means an area of a passenger car that normally does not 

contain seating and is used in passing from the seating area to the side 

exit doors.

    Witness plate means a thin foil placed behind a piece of glazing 

undergoing an impact test. Any material spalled or broken from the back 

side of the glazing will dent or mark the witness plate.

    Yard means a system of tracks within defined limits provided for the 

making up of trains, storing of cars, or other purposes.



[[Page 652]]



    Yard air test means a train brake system test conducted using a 

source of compressed air other than a locomotive.

    Yield strength means the ability of a structural member to resist a 

change in length caused by a heavy load. Exceeding the yield strength 

may cause permanent deformation of the member.



[64 FR 25660, May 12, 1999, as amended at 65 FR 41305, July 3, 2000; 67 

FR 19989, Apr. 23, 2002]