Crashworthiness strategies, which include crash energy

management (CEM), pushback couplers, and push/pull

operation, are evaluated and compared under specific collision

conditions. Comparisons of three strategies are evaluated in

this paper:

- Push versus Pull Operation (Cab Car Led versus

Locomotive Led Consists)

- Conventional versus CEM Consists

- Incremental CEM versus Full-CEM

Rail cars that incorporate CEM are designed to absorb collision

energy through crushing of unoccupied structures within the

car. Pushback couplers are designed to recede into the draft sill

under collision loads and enable the car ends to come into

contact, minimizing the likelihood of lateral buckling.

Push/pull operation refers to operating either a locomotive (pull

mode) or a cab car (push mode) at the leading end of the train.

Five cases using combinations of these three strategies are

evaluated. The basic collision scenario for each case analyzed

in this paper is a train-to-train collision between like trains.

Each train has a locomotive, four coach cars, and a cab car. The

impact velocity ranges from 10 to 40 mph.

The following five cases are evaluated:

1. All conventional cars with a cab car leading (baseline

case)

2. All conventional cars with a locomotive leading

3. Conventional coach cars with pushback couplers, with

CEM cab car leading

4. All CEM cars with a cab car leading

5. All CEM cars with a locomotive leading

A one-dimensional lumped-mass collision dynamics model

is used to evaluate the effectiveness of each strategy, or

combination of strategies, in terms of preserving survivable

space for occupants and minimizing secondary impact velocity

(SIV). Test data is used to correlate SIV with head, chest, and

neck injury. Probability of serious injuries and fatalities are

calculated based on calculated car crush and injury values. The

maximum crashworthy speed, or the maximum impact speed at

which everyone is expected to survive, is calculated for each

case.

Of the five cases evaluated, the scenario of a cab car led

conventional consist represents the baseline level of

crashworthiness. The highest levels of crashworthiness are

achieved by a consist of all CEM cars with a locomotive

leading, followed by all CEM cars with a cab car leading. The

results indicate that incremental improvements in collision

safety can be made by judiciously applying different

combinations of these crashworthiness strategies. A CEM cab

car leading conventional cars that are modified with pushback

couplers enhances the level of crashworthiness over a

conventional cab car led consist and provides a level of

crashworthiness equal to a locomotive leading conventional

passenger cars.