Prototype Design of an Engineer Collision Protection System
Authors: Muhlanger Michelle P. , Severson Kristine , Perlman Benjamin , Prabhakaran Anand , Singh Som P. , Vithani Anand R. 
Published: July 2013

This research program was sponsored by the Federal Railroad Administration (FRA) Office of Research and Development in support of the advancement of improved safety standards for passenger rail vehicles. In a train collision, the cab or locomotive engineer is in a vulnerable position at the leading end of the vehicle. As cars with increased crashworthiness are introduced into service, there is a greater potential to preserve the space occupied by the engineer following an accident. In particular, full-scale impact tests have demonstrated the engineer’s space can be preserved at closing speeds up to 30 mph. When sufficient survival space is preserved, the next objective is to protect the engineer from the forces and accelerations associated with secondary impacts between the engineer and the control cab. Given the hard surfaces and protruding knobs in a control cab, even a low speed collision can result in large, concentrated forces acting upon the engineer.

Researchers have designed a passive (i.e., requiring no action by the operator) interior protection system for cab car and locomotive engineers. The occupant protection system will protect engineers from the secondary impact that occurs following a frontal train impact, when the engineer impacts the control console. The protection system will result in compartmentalization of a 95th percentile anthropomorphic test device (ATD), and measured injury criteria for the ATD’s head, chest, neck, and femur that are below those currently specified in Federal Motor Vehicle Safety Standard (FMVSS) 208 [1].

The system that has been developed to protect the engineer includes a specialized airbag and a knee bolster with energy absorbing honeycomb material and deformable brackets. Finite element and lumped mass-spring analyses show the effectiveness of the system in limiting the injury criteria to survivable limits. Component tests have measured the key characteristics of the airbag and the knee brackets and have provided test data necessary to validate the analyses.

Two tests were conducted to validate the airbag model. A static deployment test of the airbag measured the inflation progression, the inflated shape and the internal pressure of the airbag. A drop tower test of the airbag measured the force-crush and energy absorbing characteristics of the airbag. The knee bolster assembly consists of two components. Separate quasi-static tests of the aluminum honeycomb and the knee bolster bracket measured the force-crush and energy absorbing characteristics. The component test results were used to improve the computer model and permit analysis of the entire system.

This paper discusses the prototype design, including background research, baseline definition and prototype development. The initial prototype design is analyzed using computer models. The components are tested to verify and improve the computer models. The test and analysis results are presented. Future work is planned for fabrication of the cab desk and prototype system to be used in a sled test with a 95th percentile ATD.