Accident studies indicate that conventional lap/shoulder belt systems are most effective in low-to-moderate crash severities, but are somewhat ineffective in frontal collisions more severe than a 30 mph fixed-barrier impact. The primary benefit of belt restraints in side and rollover collision modes is the prevention of ejection. However, other means of preventing ejection are also proving to be effective. Extrapolation of available data from the Australian mandatory belt use legislation suggests that U.S. fatalities would be reduced by less than 40%, even with 100% lap-shoulder belt use.
Abstract