Analysis of Collision Safety Associated With Conventional and Crash Energy Management Cars Mixed Within a Consist

Abstract

A collision dynamics model of a passenger train-to-passenger train collision has been developed to simulate the potential safety hazards and benefits associated with mixing conventional and crash energy management (CEM) cars within a consist. This paper presents a comparison of estimated injuries and fatalities for seven collision scenarios based upon the variable mix of conventional and CEM cars. Based on the analysis results, recommended car placement when mixing cars within a consist is identified. The model includes a 6 car cab car-led consist colliding with a 6 car locomotive-led stationary consist. The stationary consist is made up of all conventional cars. The moving consist has a variable mix of conventional and CEM cars. For comparison, the bounding scenarios are: - a moving consist with all conventional cars, and - a moving consist with all CEM cars. The collision speed ranges from 15 to 35 mph. Since the two car designs behave differently under impact conditions, there is a concern that there may be hazards associated with mixing the two designs in the same consist. In none of the cases evaluated is the mixed consist less crashworthy than the conventional consist. The modeling results indicate that the least crashworthy consists are ones in which a conventional cab car is leading any combination of vehicles. The conventional cab car incurs nearly all the damage and prevents trailing cars from participating in energy absorption, whether they are conventional or CEM. The most crashworthy consists are ones in which a CEM cab is leading. The CEM cab can absorb a significant amount of energy without intruding into the occupied volume. The CEM cab also allows trailing cars to participate in energy absorption, which provides further occupant protection. The recommended strategy for car placement is to put the CEM car(s) at the leading end(s) and the conventional car(s) at the trailing end or in the middle of the consist in push-pull operation. There is also significant benefit to placing the seats in the leading CEM car or two so they are rear-facing. Rear-facing seats can reduce the severity of secondary impact injuries because the occupant is already in contact with the seat in the direction of travel and does not develop a significant velocity relative to the seat.

The Influence of Train Type, Car Weight, and Train Length on Passenger Train Crashworthiness

“…The study results presented in this paper, in combination with the study results presented in [2,3], show that CEM cars can be introduced into service with minimum risks and with great potential benefit. Previous studies have shown that the crashworthiness performance of a consist which is a mix of conventional and CEM equipment is never worse than the performance of an all conventional equipment consist in a trainto-train collision, and is always better when a CEM car is the impacting cab car.…”

“…The CEM force crush concept can be viewed as a series of steps, as shown in Figure 3. The CEM curve used for this study is a specific design suggested in [3]. There are other design possibilities that would have the necessary force/crush behavior.…”

“…The third study [3] addressed some of the potential concerns of putting CEM equipment into service. Since rail passenger equipment has a service life in the range of 30 years or more, any new CEM equipment would necessarily be operated mixed with conventional equipment.…”

Preparations for a Train-to-Train Impact Test of Crash-Energy Management Passenger Rail Equipment

“…As part of the rail passenger equipment crashworthiness research, studies have been conducted to evaluate the influence of operational factors in train-to-train collisions [19,20,21]. These studies show that CEM cars can be introduced into service with minimum risks and with great potential benefit.…”

Crush Analyses of Multi-Level Equipment

“…FRA may then propose alternative design strategies to better protect the occupied space of passengers and crewmembers and limit the forces that they are subjected to as they ride out a collision or derailment. In addition to developing alternative design strategies, effectiveness studies were also conducted to demonstrate the potential safety benefits for incremental inclusion of structural and/or interior crashworthiness features [1,2].…”