Abstract
Keywords - Accident analysis, crashworthiness, injury probability, statistics, JNCAP
Abstract - Effect of factors on occupant injury in automobile accidents in Japan was analysed from comprehensive perspective. Relationships among the factors were also carefully scrutinized. ITARDA (Institute for Traffic Accident Research and Data Analysis) database compiled based on police data were used for the analysis. 147 models were selected for the analysis based on registered numbers. Vehicle weight, and size, etc., which were independently investigated, were selected as explanatory variables together with driver age characteristics, seatbelt use rate and model year. The influence of each factor was successfully captured. The effect of vehicle mass was clearly discernible in major injury indices. In addition, the higher the vehicle height is, the smaller the accident-incurred rate becomes. Moreover, factors influencing fatal accident-incurred units per 10,000 registered vehicles include vehicle height and model year. At the same time factor parameters have found to correlate with each other in various combinations. When looking at the age group, although 30-49 years old showed lower injury risk compared to other age groups, the reason behind this was found not only because they drive safely, but because they choose larger vehicles. On the contrary, age group of less than 25 years old displayed higher injury risk not only because some of them tend to drive on high-risk behaviour, but also they frequently drive smaller cars.
Latter half of the present study discusses the influence of 24 models evaluated in JNCAP on field accidents focusing only on frontal crashes belted drivers involved. Before the analysis, relationships between factor parameters such as JNCAP performances, vehicle mass and size was identified. The confirmed relationship contains vehicle height and side impact performance, and vehicle length and frontal impact performance. Other clear relationships were not identified. Some relationships were detected in both full-lap and offset frontal impacts over vehicles involved occupant injuries per 10,000 units.
Data without any modification on age, and gender, etc., were used for the analysis. Direct evaluation of relationship between explanatory variables and objective variables without any modification is primarily crucial. This is because parameter modification may fail to obtain accurate influence of the parameters a researcher focuses on, if explanatory variables the researcher does not focus on have great influence on the focused parameters.