The purpose of this paper is the comparison of the protection efficiency between three-point belt and air bag systems under various crash conditions.
Dynamic tests have been performed with subcompact vehicles (Renault R 12) in which two dummies were restrained, either by three-point belts with load limiting devices, or by air bags consisting of solid gas generators and bags including porous outlets (the driver's knees were protected by a collapsable structure).
Three types of crashes were chosen:
frontal barrier crash at 50 km/h (13,9 m/s)
head-on crash between two vehicles with overlap at 50 km/h (13,9 m/s)
crash against a guardrail at 80 km/h (22 m/s) with 30° angle of incidence.
The comparison drawn from commonly used biomechanical indices shows that the three-point belt ensures a protection in each analysed crash type but it should be improved in order to reduce head deceleration. The air bag results depend on the crash type and show the problems of adaptation in a subcompact vehicle.
The frontal barrier crash tests conducted with another type of dummy reveal that the results obtained for the two restraint types depend on the dummy, so that the efficiency assessment is difficult.