Developed in the early 1980's, the flail space model has become the standard method for estimating occupant risk in full-scale crash tests involving roadside safety features. The widespread availability of airbags and increased seat belt usage rates in today's vehicle fleet, however, raise serious questions regarding the validity of the model. Recent implementation of Event Data Recorder (EDR) technology in a number of late model vehicles presents a different perspective on the assessment of the validity of occupant risk based on the flail space model. EDRs are capable of electronically recording data such as vehicle speed, brake status and throttle position just prior to and during an accident. Of particular interest is the EDRs ability to document the deceleration of a vehicle during a collision event. This thesis presents a methodology utilizing EDR data to investigate the capability of the flail space model to predict injury to airbagrestrained occupants. Results of a preliminary analysis are presented based on implementation of the developed methodology on a limited data set.

A major part of the analysis is limited to the occupant impact velocity due to complications in estimating the occupant ridedown acceleration from the available EDR data. The longitudinal occupant impact velocity is found to be a good predictor of overall injury, chest injury and, to a lesser extent, lower extremity injury. For the head, and upper extremity body region, the longitudinal occupant impact velocity is a weak predictor of injury. In the analyzed data set, the occupant impact velocity is found to be more significant predictor of overall occupant injury than the occupant ridedown acceleration.