PATTERNS OF WHEELCHAIR RESPONSE AND SEATING-SYSTEM FAILURES IN FRONTAL-IMPACT SLED TESTS Miriam A. Manary, Laura M. Woodruff, Gina E. Bertocci, and Lawrence W. Schneider University of Michigan Transportation Research Institute University of Pittsburgh ABSTRACT Data from 259 frontal impact sled tests of commercial wheelchairs and seating systems were compiled and retrospectively analyzed. These data have general application to the development of additional design and performance requirements for transit wheelchair (WC) standards, and are specifically needed to guide the design and performance specifications of a reusable surrogate wheelchair base (SWCB) that can be used for frontal-impact testing of WC seating systems. BACKGROUND Section 19 of ANSI/RESNA WC/Vol.1 Wheelchairs Used as Seats in Motor Vehicles (WC/19), establishes performance standards for WCs that are used as seats in motor vehicles in an effort to improve the safety of WC riders in the event of a motor vehicle crash (1). WC/19 is a test of a complete WC, including the frame and seating system, but many WC users need to interchange WC frames and seating to meet their individual needs. Crash testing of each combination of WC frame and seating system is costly and time consuming. Therefore, a method of testing seating systems in isolation to verify their appropriateness for the transit environment is advantageous. Work by Ha, et al., (2) attempted to determine seating system integrity through low-cost, quasi-static testing but these methods do not simulate the dynamic interactions of the occupant/WC system and are not considered to be a suitable alternative to dynamic testing. Another approach is a reconfigurable, reusable surrogate wheelchair base (SWCB) that can accommodate a variety of WC seating systems. An initial prototype has been developed but in order to enhance the performance and the acceptability of the SCWB, it is desirable to match its features to the relevant performance characteristics of commercial WCs. OBJECTIVES The general objective was to quantify and document the kinematics, performance characteristics, and failure modes of different types of WCs and WC seating systems during frontal impact tests conducted at UMTRI since January 1998. An immediate objective was to use a subset of these data to guide the design and performance specifications of a SWCB that can be used for dynamic testing of WC seating systems independent of commercial WC bases. METHODS UMTRI sled test reports, photographs, and high-speed videos from WC/19 tests sponsored by seventeen WC and WC seating companies were reviewed to establish a set of over forty variables related to frontal-impact tests of WCs and WC seating systems. These variables include physical descriptors of the WC, the test setup geometry, and the size and weight of the anthropomorphic test device (ATD) used, peak ATD excursions, ATD accelerations, peak WC excursions, WC side-view rotational kinematics, WC frame deformation, seating-system failure modes, as well as peak tiedown and restraint forces. Seating system failures were of particular interest for validating the ability of the SWCB to produce similar types and levels of seating system loading as observed with commercial WC frames.