Vehicle Occupant Nationality Study: Japanese

Abstract

Few previous studies have compared postures for drivers of different nationalities. In the current study, 73 Japanese citizens who were licensed to drive in Japan participated in a laboratory study of driving posture, belt fit, and body shape using methods identical to those used in an earlier study of US drivers. The data from the two studies were pooled for analysis. As expected, the Japanese study population was shorter in stature and lower in body weight than the US study population. In general, the effects of nationality were small compared to the residual variance in the regressions. After accounting for body size, the Japanese study population placed their seats 13.5 mm further rearward than the US study population and were an average of 1.2 degrees more reclined. Importantly, no significant differences between study populations in the effects on posture of steering wheel position or seat height were found. The lap belt placement was much closer to the pelvis in the Japanese study population; most of this difference could be accounted for by lower body mass index. Statistical body shape models for standing and seated postures were developed using pooled data from 235 US and Japanese subjects. The results showed differences in body shape after accounting for stature, body weight, sitting height and age that were primarily concentrated in the torso. The results of the study are limited by the lack of Japanese individuals with high body mass and age greater than 60 years.