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Status Report, Vol. 45, No. 6 | June 19, 2010 Subscribe

Stability control reduces fatal crash risk by a third

Electronic stability control (ESC) for passenger vehicles remains one of the most effective technologies yet developed for preventing fatal crashes, especially single-vehicle rollovers. ESC helps drivers in the event of loss of control at high speeds or on slippery roads. It lowers the risk of a deadly crash by 33 percent and cuts the risk of a single-vehicle rollover by 73 percent.

These are the main findings of a new Institute study updating earlier estimates of the crash-avoidance technology's benefits. The new estimates are about 7-10 percentage points smaller than the Institute found in 2006. One reason may be differences in the way early ESC-equipped vehicles were driven and how they were used compared with the vehicles of today.

"Sports cars and luxury models were the first to get ESC," says Anne McCartt, Institute senior vice president for research. "People tend to drive these cars faster and more aggressively than family vehicles, getting into the risky situations that lead to the loss of control crashes ESC is designed to prevent."

Lots of everyday drivers "rarely get into situations where ESC would take over," McCartt adds. "The good news is that ESC still works well when it's needed. That's why it's one of the requirements for Top Safety Pick."

ESC could have prevented an estimated 15,600 fatal crashes in 2002-08 if all new passenger vehicles had been equipped with the technology.

First introduced in 1995, ESC helps drivers control their vehicles during high-speed maneuvers like entering curves too fast or swerving to avoid animals on slippery highways (see "Update: electronic stability control," June 13, 2006). Even before a driver knows there's a problem, ESC senses when a vehicle strays from the intended travel path or begins to spin out. Then the system automatically brakes individual wheels and sometimes reduces throttle to keep the vehicle under control and moving in the intended direction of travel.

In the latest study, Institute researchers examined a total of 10 years of crash data, comparing fatal crash involvement rates per registered passenger vehicle for identical models with and without ESC. Data on fatal crashes during 1999-2008 were from the Fatality Analysis Reporting System, a federal database of fatal crashes in all 50 states.

ESC reduces fatal crash risk by 49 percent in single-vehicle passenger vehicle crashes and 20 percent in multiple-vehicle crashes. Effectiveness estimates are higher for SUVs than for cars — 35 percent for SUVs compared with 30 percent for cars — but the difference isn't statistically significant. SUVs tend to have a higher center of gravity than cars, so they are more likely to get into the kinds of loss-of-control and rollover crashes that ESC helps prevent.

Many single-vehicle crashes involve rolling over, and ESC plays a big role in preventing these types of crashes. ESC was associated with a 73 percent reduction in single-vehicle rollover fatal crash involvement risk and a 59 percent reduction in single-vehicle fatal crash risk on wet or slippery roads. For the 2010 model year, ESC is standard on 88 percent of cars, 100 percent of SUVs, and 62 percent of pickups. By 2012 all new cars, SUVs, and pickups must have ESC.

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