WASHINGTON—Yet another recent study suggesting that anti-lock brakes may be more hazardous than conventional systems has caused widespread puzzlement in the automotive industry. According to the study by the Insurance Institute for Highway Safety, cars equipped with anti-lock brakes were 24 percent more likely than cars without ABS to be in crashes that killed their own occupants. The organization researches auto safety issues for the insurance industry.
``We've all been puzzled'' by the findings, said a spokesman for the American Automobile Manufacturers Association. ``We think there's nothing wrong with ABS technology, though. There may be a problem with driver interaction with the technology.''
Insurance institute President Brian O'Neill now thinks ``everything about the on-the-road performance of anti-lock brakes'' is a puzzle.
``I'm sure what we're finding has some driver effects—drivers over-driving, not properly understanding how ABS works. We still don't know,'' he said.
Previous studies on ABS effectiveness conducted by auto manufacturers, the National Highway Traffic Safety Administration (NHTSA), the Canadian government and the insurance institute also failed to show that the systems have clear benefits.
Focus on fatal crashes
The studies have shown anti-lock brakes provide some benefit on slippery, wet roads, but also an increased likelihood that cars equipped with ABS-will be involved in single-vehicle crashes.
That would account for the results of the study released last December by the Insurance Institute for Highway Safety. The new study was the first to focus solely on fatal crashes.
Using NHTSA's Fatal Accident Reporting System data, the institute evaluated the crash experiences of two sets of cars to gauge the performance of those with ABS:
One set comprised mid- to late-1980s sports and luxury cars that had no ABS available one year and standard ABS the next, and no other significant design change.
That part of the study covered crashes that occurred from 1986-95 and included 485 crashes of cars with ABS and 493 crashes of cars that did not have ABS.
The other set were less expensive and available to a broader range of customers: 1991-92 Chevrolet Cavaliers, Corsicas and Berettas; Pontiac Sunbirds and Grand Ams; and Buick Skylarks.
ABS was unavailable on those cars in 1991, but General Motors Corp. made the systems standard for the 1992 model year.
Crashes involving the GM cars occurred from 1993-95 and included 485 involving ABS cars and 581 without ABS.
The GM vehicles fared somewhat better in the Insurance Institute study than the older-model luxury cars.
The GM cars were in 22 percent fewer multiple-vehicle fatal accidents on dry roads than non-ABS cars and 13 percent fewer on wet roads. They were involved in 74 percent fewer pedestrian deaths than non-ABS cars on wet roads and 14 percent fewer on dry roads.
But people in the GM cars with ABS were in 19 percent more fatal single-car crashes on dry roads than non-ABS cars and 44 percent more single-car fatalities on dry roads.
The luxury/sport cars were involved in 20 percent more of the fatal multiple-car crashes on dry roads than non-ABS cars and 65 percent more single-vehicle crashes on wet roads.