SUV Rollover Risks

Despite advances, SUVs pose a higher rollover risk.

Despite great advances in safety technology, vehicles with higher ground clearance still pose a higher rollover risk than vehicles that sit lower. Because one of the key defining characteristics of sport utility vehicles (SUVs) is their greater height, they are more likely to roll over in an accident than passenger cars. However, today's SUVs are significantly safer than earlier models and are equipped with safeguards to avoid a rollover.

Simple Physics

Unfortunately, technology cannot defy the laws of physics. These laws dictate that an object with a higher center of gravity is less stable and easier to topple than an object of similar weight with a lower center of gravity. We all understand this concept intuitively. Prop up a block of wood lengthwise, and it is easier to topple with the push of a finger. Place it on its tall side, to make it short, and it is far more difficult, maybe even impossible, to topple the same object.

Because of this simple fact, sports cars sit low to the ground, and many are nearly impossible to roll over, even if you try. A low and wide sports car will almost always slide sideways if you push it beyond its limits, just like the wood block placed on its side is more likely to slide on the carpet, as opposed to rolling over, when pushed. An SUV or a tall truck, however, can easily topple when pushed beyond the limits of adhesion.

High Up

SUVs were marketed as go-anywhere type of alternatives to cars. Soon, however, it became obvious that the vast majority of people weren't really going anywhere near rough terrain in their SUVs, but simply driving them on paved city streets.

The most important reasons people purchase these vehicles are their higher ground clearance and more interior space. A higher seat gives the driver a commanding view of the road and makes it easier to get in and out of the vehicle.

It is also easier to load and unload items onto a SUV, and many parents find it easier to work with child seats placed on the high rear seat of an SUV, as opposed to bending down to get to the infant on the relatively low back seat of a car.

This higher seat position is impossible to achieve, of course, without increasing the overall height of the vehicle. Greater interior space, likewise, is largely a function of more vertical room in the vehicle. Therefore, SUVs have to be taller if they are to satisfy the consumers' needs.

Statistics

Government statistics clearly show a higher risk of rollover for SUVs, compared to all other vehicle types.

According to the National Highway Transportation Safety Administration, passenger cars have an average chance of rollover of 12 percent in a single-vehicle crash, whereas SUVs have a 27 percent chance of a rollover under similar conditions. The rollover risk for SUVs is higher than vans and pickups as well.

Note that, the range for rollover risks is fairly broad among SUVs, with some carrying a rollover risk of more than 40 percent, while others could have a mere 15 percent chance of rolling over. On average, however, SUVs tend to roll over far more easily than cars.

Electronics Help

The most important technological advancement to avoid rollover accidents is electronic stability control or ESC. ESC does not increase the available adhesion, but it will make it harder to unintentionally exceed the limits of the vehicle.

Depending on the model, ESC systems may vary in their precise mode of action and sophistication, but they usually prevent rollovers by selectively applying brakes on one or two wheels of the vehicle to help the driver retain control during heavy maneuvers.

In simpler terms, the systems will prevent the vehicle from assuming a position on the road where the lateral forces will exceed the amount of traction the tires can provide. ESC will not prevent every possible rollover but will reduce the probability of a rollover. A list of vehicles equipped with ESC is available on the government's SaferCar website.

Better Driving

In addition to choosing an SUV equipped with ESC, drivers can minimize the risk of a rollover by learning how to better control their vehicles. Learning proper maneuvering techniques, avoiding harsh maneuvers and using caution on rural roads are important elements of operating an SUV safely. The government's SaferCar website offers tutorials as well as important tips on these and other safety issues.

References

• Safer Car: Vehicle Class Comparison
• Safer Car: List of Vehicles with ESC
• Safer Car: Proper Maneuvering Techniques