How It Works: Stability Control Brings Stability to SUV Segment
Electronic stability control (ESC) systems are already commonplace among the luxury car set, and are now becoming more and more available on entry-level vehicles as well, especially SUVs. Just look at the standard equipment lists on a new Hyundai Tucson or Kia Sportage, both selling for around $20K, and Ford and Chrysler Group have announced that all upcoming SUVs will feature ESC across their respective lineups. Ford’s recently updated Explorer was testament to this initiative, as is Dodge’s upcoming 2007 Durango. These aren’t the only brands to adopt the ESC credo either. No, expect this trend to expand throughout an SUV segment that is doing its best to restore confidence after rollover incidents did their part in slowing sales, as well as become more available within the passenger car segment too.
And just what is stability control? To explain further, ESC systems use a vehicle’s antilock brake mechanisms to push and pull a wayward vehicle back in the direction the driver is steering. While it is possible for an ESC system to engage on dry pavement, they are most useful during slippery conditions, such as wet, snowy and/or gravel road surfaces. Simply explained, if a vehicle oversteers, or slides sideways at the rear wheels, ESC applies an appropriate level of force to the opposite front brake, and other braking points if necessary, in order to realign the vehicle’s rear quarters. Similarly, if a vehicle is understeering, or pushing forward on the front wheels, breaking traction and potentially causing an unintentional lane change, ESC will apply the brakes to the inside wheels to pull the car back into its lane.
While not all ESC systems are identical, the hardware used is similar. Certainly there are variations in the way the systems are programmed to respond to a loss of control, with some stability control systems activated sooner than others and some still that will cause a vehicle to slow down faster when needed, but that’s about it. The individual effectiveness of these systems does vary, however, due to such aforementioned parameters as well as the efficiency of the antilock braking system being deployed, the weight and dimensions of the vehicle, agility of its suspension system, and so on.
Incidentally, electronic stability control goes by many names. GM has named its version StabiliTrac, while Ford calls ESC AdvanceTrac. DaimlerChrysler uses Electronic Stability Program (ESP), with other names including Vehicle Dynamics Control (Subaru), Dynamic Stability Control (Volvo), Vehicle Stability Assist (Honda), and Vehicle Stability Control (Toyota).
Whatever the name, what matters more is that stability control systems, in general, save lives. According to a U.S. National Highway Traffic Safety Administration (NHTSA) study, single-vehicle crash risks for cars were reduced by 35 percent while a 67 percent reduction was experienced by SUVs equipped with ESC systems. Fatal single-vehicle crashes were reduced about 30 percent (cars) and 63 percent (SUVs). An Insurance Institute for Highway Safety (IIHS) study experienced similar findings.
“For most drivers ESC isn’t likely to activate frequently. For example, it won’t prevent most of the fender-bender crashes that occur so often in stop-and-go traffic,” says Susan Ferguson, Institute senior vice president for research. “ESC is designed to help a driver in the relatively rare event of loss of control at high speed or on a slippery road.”
Together these studies indicate that widespread application of ESC could save more than 7,000 American lives per year; and another 700 in Canada if you go by the 10 percent population rule. If all vehicles on U.S. roads had ESC, it might prevent as many as 800,000 of the 2 million or so single-vehicle crashes that occur each year. Incidentally, about half of the 28,000 fatal passenger vehicle crashes that occur each year in the U.S. involve a single vehicle.
Moral of the story: make sure your next vehicle is equipped with electronic stability control, it’s a lifesaver.