Rollover accidents are serious, about one out of six light vehicle fatalities occurs in a rollover accident, for heavy trucks it's about 50%. Sometimes the rollover event is not the fault of the vehicle. It is not that difficult, for example, to roll a car if it leaves the highway, especially following an impact. Here the issue may be the crashworthiness of the vehicle with respect to foreseeable rollover events; if, as is often the case, the occupants are injured due to excessive roof crush.

Some vehicles are very prone to rollover on the road without a wheel trip, they can be upset by the tire forces generated by steering maneuvers. Heavy trucks are a good example of this, because they are high and narrow they go over very easily. Not much can be done about this except to provide protection for the driver in a rollover accident. But some light vehicles - mostly four wheel drive sports/utility vehicles - can also be made to rollover in response to driver steering input. They exhibit this behavior because they are too narrow (and also too short) for their height.

Rollover propensity is an issue which has been litigated extensively but is not regulated. Manufacturers have defended poor designs on the basis of theories about performance requirements for the types of vehicles involved. The theories are all false in our view, and not that difficult to refute.

A case study: The Bronco II

Occupant protection in rollovers: a European view...

For more on heavy truck (semi's) rollovers go to the Truck Safety page .