The results of the bidisciplinary accident investigation indicate that the frequency of side impact accidents is high (20 percent of car accidents) and especially that they are more serious than other accidents.

The first part of the study shows that the severity of injuries increases with intrusion, especially for occupants seated on the impacted side.

In the second part, the results of car-to-car side impact crashes, with and without intrusion, are analysed. It is shown that nonintrusion, because of stiffened side steel plates, decreases the accelerations and forces exerted on struck car dummies, while not appreciably increasing those applied on the restrained dummies in striking cars.

This leads us to think that it is possible to reduce the severity of side impact accidents by preventing intrusion.

Since early 1970, the Impact Research Laboratory of the French National Highway Safety Organisation has been carrying out a bidisciplinary investigation on highway accidents occuning in the Lyon area. [1] In 1972, a second team was set up at Salon-de-Provence (near Marseille), to work in cooperation with the local hospital.