At the request of METROLINK, the Federal Railroad

Administration (FRA), with the Federal Transit Administration and the

American Public Transportation Association, formed the ad hoc Crash

Energy Management Working Group in May 2005. This group

developed recommendations for crush zones in passenger rail cars for

METROLINK to include in its procurement specification. The Volpe

Center provided the Working Group with technical information from

the research on passenger rail equipment crashworthiness it is

conducting for FRA. METROLINK released its specification,

including the recommendations from the Working Group, on

September 16, 2005, as part of an invitation for bid.

The specification includes three levels of requirements: train,

car, and mechanism. The train level requirements specify a collision

scenario for which there must be no intrusion into the occupied areas

and limits on the relative velocities at which the operator and

passenger may impact interior surfaces. The car and mechanism level

requirements follow from the train level requirements. The car level

requirements include specifications for a cab end crush zone capable

of absorbing 3.0 million ft-lbs of energy and a non-cab end crush zone

capable of absorbing 2.0 million ft-lbs. There are also specifications

on the crush zone kinematics and on the target force/crush

characteristics. Mechanism level requirements include specifications

for the coupling mechanism, the load transfer mechanism, and the

principal energy absorption mechanism. The coupling mechanism

permits the coupler to push back, allowing the ends of adjacent cars to

remain aligned and come together during an impact. The load transfer

mechanism transmits the load from the adjacent equipment into the

crush zone in a manner that allows the principal energy absorption

mechanism to function as intended. The cab end load transfer

mechanism can include a deformable LD that acts similarly to an

automobile bumper, and resolves eccentric impact loads into loads that

can be appropriately reacted by the supporting structure. The

principal energy absorption mechanism is the section of the carbody

structure intended to deform gracefully and to provide most of the

required energy absorption.

The specification prescribes performance for the train, the cab

and trailer cars, and the mechanisms. Each requirement includes

quantitative criteria for evaluation of compliance. The Working Group

extensively discussed various evaluation methodologies, including

non-linear large deformation finite element analysis and dynamic

component tests, and worked to assure that practical evaluation

methodologies are available for each requirement. For components

critical to the functioning of the crush zone, tests are required. This

paper describes the requirements, the associated criteria, and the

available evaluation techniques. The technical bases driving the need

for each of the requirements are discussed.