Glance at the world’s fastest race cars and you’ll notice some striking similarities. They’re all wider than they are tall and extremely low-slung. That’s because the laws of physics dictate that the lower a vehicle’s centre of gravity, the better it will corner at high speeds. However, low-slung vehicles don’t take kindly to deep snow, potholes or rough terrain. That’s why many Canadians have opted for sport-utility vehicles (SUVs) in recent years.
These hulking machines – which are often favoured by motorists looking for an added margin of safety – have an Achilles heel. Their higher centre of gravity makes them more prone to rollovers during high-speed crashes.
Just as a person on a bar stool is more prone to tipping over than someone in an armchair (even if they’ve both had the same number of drinks), SUVs tend to be more top-heavy than cars and thus more tipsy at the limits. While rollovers are rare, they’re particularly destructive. They occur in only one out of every 25 crashes in Canada, but they’re responsible for four out of every 25 crash deaths. About 25,000 rollover crashes occur annually in Canada, resulting in 15,000 to 17,000 injuries and 500 deaths. According to the U.S. Department of Transportation’s National Highway Traffic Safety Administration (NHTSA), the fatality rate for SUV occupants in rollovers is nearly triple the rate for those in cars.
These grim statistics prompted the NHTSA to introduce a set of rollover resistance ratings in 2001. The rating system relates how top-heavy a vehicle is to the risk of a rollover in a single-vehicle crash. A vehicle that rates one star out of five has a rollover risk in a crash of more than 40 per cent. A vehicle rated five stars has a rollover risk of less than 10 per cent. Predictably, SUVs fare worse in the ratings than cars. The rating system has been criticized, however, because it’s based on a mathematical formula rather than on road-handling tests. After all, it’s on the road where the driver – not just the vehicle – plays a key role in most so-called accidents.
Just as it’s important for people perched on bar stools to be aware of their surroundings and their drinking limits, it’s important for drivers to adjust to road conditions and avoid actions that could make them dangerously tipsy.For instance, a sleepy driver may wander onto the shoulder and be startled by the wheels hitting the gravel. If you hit the brakes and swerve back toward the road, you increase your risk of rolling, says Jim White, chief of vehicle systems research for the road safety directorate of Transport Canada. The better strategy? Ease up on the accelerator, let the vehicle slow down and, when it’s safe to do so, pull back onto the pavement. Stay in control and know your vehicle’s rollover risk because, if you own an SUV, any off-road excursions should be by choice and not chance.
Maryanna Lewyckyj is consumer advocate for the Toronto Sun. She conducts car care seminars for women through her company, Autophobics Anonymous.
Don’t roll the dice when you drive. Heed these tips: