Rollover SUV Safety Testing

•Proposed Rollover Testing
More than 10,000 people die each year in rollover crashes. This can happen in almost any vehicle, so manufacturers use lab settings to roll vehicles over to verify if they can withstand an accident without jeopardizing passenger safety. This has helped lead to safety developments such as side-curtain and head airbags.

Does the U.S. government check vehicles to see if they're rollover prone? Well, sort of. The National Highway Traffic Safety Administration offers rollover-resistance ratings for new cars, light trucks, and SUVs. These ratings aren't based on actual track tests or laboratory rollover crash tests. Instead, they're a mathematical computation for each vehicle, which NHTSA calls the Static Stability Factor, and are based on the vehicle's track width and center of gravity. The SSF was originally chosen over real testing because it best estimates a vehicle's propensity to roll over when it's tripped by impacts with curbs, soft soil, potholes, guardrails, or other hazards that unweight a vehicle and help it tip over.

While the majority of rollovers are of the tripped variety, there are also those in which tire-to-road friction is the only external force acting on the vehicle that rolls over. In other words, a driver swerves to avoid something in the road and loses control. The vehicle slides on the pavement and tips over on its own without striking anything that forces it to roll over. NHTSA says the best way to judge how well a particular vehicle will do in these untripped rollovers is to put them through a series of track tests at highway speeds. These proposed tests involve a series of maneuvers conducted by NHTSA using a computer automated steering controller in place of a human test driver to assure accuracy and repeatability. Each vehicle tested receives a star rating of one to five, with five being best. While the testing procedure has yet to be finalized, Congress has mandated that NHTSA implement this kind of testing for the current model year for select cars, trucks, and SUVs.

Passenger vans, such as the Chevrolet Express and the Ford E-Series, are getting extra attention in the area of rollovers. Recent NHTSA research has found that the risk of a rollover is greatly increased when 10 or more people ride in a 15-passenger van. This increased risk occurs because the passenger weight raises the vehicle's center of gravity and causes it to shift rearward. As a result, the van has less resistance to rollover and handles differently from other commonly driven passenger vehicles, making it more difficult to control in an emergency situation. Placing any load on the roof also raises the center of gravity and increases the likelihood of a rollover.

While no specific new laws regarding 15-passenger vans have been enacted, NHTSA is conducting additional research into how to make full-size vans safer. It says that over the past decade, 80 percent of people killed in rollover crashes in 15-passenger vans were unbelted. Because of this, NHTSA says no research is needed for it to recommend that using seatbelts can dramatically reduce occupant risk of being killed or sustaining serious injury in a rollover.