Restraint systems are either active or passive. If active (usually safety belts), they offer good individual effectiveness and low cost, but because of low use rate, have low benefit on the societal (national) level. Passive systems eliminate dependency on use rate, therefore promise high societal benefit, but usually at high cost in dollars and/or convenience. Such restraints, whether active or passive, serve primarily to augment passive protection already offered in passenger cars like the energy absorbing column, high penetration windshield glass, etc., which accident data indicate can provide a basic level of protection, and do help reduce the effects of a collision.
