SAFETY IS NO ACCIDENT

Modern cars and light trucks offer an alphabet soup of active safety helpers. Just how effective are they?

- CSABA CSERE

EVER SINCE ANTI-LOCK BRAKES STARTED TO PROLIFERATE IN THE 1980s, our cars and trucks have come with an increasing variety of advanced driver-assistance systems, or ADAS. A modern vehicle might have electronic stability control (ESC), forward-collision warning (FCW), automated emergency braking (AEB), various devices to help keep it in its lane, adaptive cruise control, and more. But do these systems contribute measurably to safety?

A little over 20 years ago, I wrote a column examining anti-lock-braking systems (ABS) and ESC. Each worked exactly as promised, and we were—and are—big fans of both. But did they improve safety? Good studies existed for the technologies, and to our shock, we found no evidence that ABS improved safety at all. ESC, on the other hand, was a blowout winner, reducing single-vehicle fatal crashes by 40 percent in one study and 56 percent in another. Subsequent studies have largely confirmed these observations.

The difference seems to be that anti-lock brakes require a skilled driver to actualize their benefits. It turns out that many people don’t press the brake pedal very hard—even when facing impending doom—nor do they try to steer around obstacles while braking. So drivers weren’t taking advantage of the technology. Meanwhile, with ESC, all a driver needs to do is continue steering in the general direction desired while the technology helps the car go where the driver intends.

Given these benefits, the National Highway Traffic Safety Administration (NHTSA) made ESC mandatory starting with the 2012 model year. This essentially made ABS mandatory too, which wouldn’t make sense except that the technology was a precursor to ESC. Without the ability of ABS to control all four of a vehicle’s brakes individually, ESC would be impossible.