Our retired CHiP 'OldBaldGuy' has posted before stating he never saw a restraining belt failure. I've had one occasion to use a knife in a roadside emergency. A VW convertable was in an accident.The driver's door was buckled and the passenger side blocked by a retaining wall. Older Beetles are somewhat notorious for fuel line leaks and engine fires. There was some fuel leakage and the driver screaming to get out. I cut the top open and he climbed out. Then I had to literally force him into my tank Volvo. Standing anywhere on a California freeway is asking for it. My greatest concern is going off the roadways. Stories are legion of people found injured or deceased sitting wrecked beyond immediate view. I would be more concerned with a accessable cellphone, whistle or best of all portable horn on a compressed charge.