Comparison of Occupant Fatality Factors in Underride Passenger Car Accidents in India and USA

Underride accidents constitute around 5% and 4% of all accidents in India and the US respectively. Yet, the occupant fatality risk is the highest in this accident configuration when compared to other configurations for passenger cars. Especially in India, the fatality rate is even higher due to minimal usage of underride protection devices in the front, rear and sides of commercial vehicles along with poor passenger vehicle crashworthiness. This study specifically aims to compare the factors influencing occupant fatality in the rear underride accidents in India and the US. Given the large number of variables involved in an accident and their complex interaction in a small duration, it was realized that a statistical analysis of this nature will only give an insight into the accident risk trends. The influencing factors are identified by performing Principal Component Analysis (PCA), which is a linear feature extraction technique. The accident databases considered for this study are Road Accident Sampling System India (RASSI) and National Automotive Sampling System-Crashworthiness Data System (NASS-CDS). After querying, about 88 cases from RASSI and 202 cases from NASS-CDS were extracted, where a passenger vehicle was involved in a rear underride accident with a commercial vehicle. The relevant variables involved in the rear underride accidents were initially identified for analysis, followed by an observation of their trends. The data corresponding to these variables were analyzed using PCA. The variables which had the highest influences were identified by their corresponding loading scores. The results were discussed to understand and compare the variables that influence rear underride accidents in India and the US. The limitation of the study is that the accident data collected in RASSI database is not yet representative of national accident data, and that NASS-CDS data has minimal information regarding commercial vehicle involved in the accident.