Abstract
The Laboratory of Accidentology, Biomechanics and studies of Human Behavior PSA RENAULT (LAB, F) have been carrying out road accident studies for 40 years. It now owns a database including 15,500 inspected cars corresponding to 28,000 occupants with 73,000 detailed injuries. During the last forty years, this accident data collection has helped the French car manufacturers to provide a better protection to the car occupants involved in a collision.
This paper aims at showing the interest of the follow-up of car fatalities causations coupled with long term studies in Biomechanics. For this purpose, it presents, as an example, the chronological evolution of the improvements in passive safety technologies since the 80’s and their effectiveness assessed in terms of injuries reduction for the front car occupants involved in frontal impacts.
In 1980, 12,510 persons died on French roads. Among these fatalities, more than a half were car occupants. Among them 47% died in a frontal collision: all body regions were highly vulnerable, i.e. sustained serious or fatal injuries. Road traffic fatalities dramatically decreased over the last three decades to reach the number of 3,994 fatalities in 2010.
Accident analysis shows that the light structures of cars built in the 80’s had to be made stiffer to provide front car occupants with a better protection in frontal impacts.
Subsequently, in the beginning of the nineties, the tendency was in the stiffening of the structure of cars. A significant decrease of the head and neck injury risks was then observed due to the release of head airbags for the drivers (in France) at the same period.
The tendency was reversed for the thorax and abdomen creating a real challenge for car manufacturers. In fact, vehicle stiffness maintained high decelerations applied by the seatbelt to the thorax of the front car occupants in frontal impacts and seat structures collapsed and increased abdominal injuries due to submarining. This issue was partially addressed by car manufacturers in the last nineties by the introduction of load limiters and stronger front seat stiffness.
In the years 2000, the car were beneficing of stiffer front structure elements in conjunction with the implementation of improved frontal airbags and new load limiters coupled with new generations of seatbelt pretensioners. Passive safety was then thought through a comprehensive concept. All body regions have directly benefited from these last improvements: serious injuries and fatal risks have considerably decreased. Thanks to the passive safety technologies (among others) fatal and serious injury rate of the belted front occupants in frontal impacts was divided by half over the last three decades.
Keywords: Passive safety, injury mechanism, accident analysis, occupant protection, frontal impact