WASHINGTON-An insurance industry study of vehicles with four-wheel antilock brakes has found that they are involved in as many accidents, and sustain as much damage as those without the highly touted ABS systems. However, a federal regulator disagrees, saying there are flaws in the study by the Highway Loss Data Institute (HLDI), and more definitive data is needed before determining whether ABS is successful in preventing passenger car accidents.
``The study is interesting, but people probably need to stay tuned for further information,'' said Barry Felrice, associate administrator for rulemaking at the National Highway Traffic Safety Administration.
NHTSA currently is accepting comment on whether to require antilock braking systems on passenger cars and light trucks. Mr. Felrice faulted the HLDI study, among other things, for including too few cars and not breaking down available data far enough.
The HLDI is an affiliate of the non-profit Insurance Institute for Highway Safety, which is supported by the insurance industry and dedicated to reducing highway injury, death and property damage.
The antilock brake study appeared in the Jan. 29 issue of Status Report, an IIHS publication.
``What will surprise a lot of people is that antilocks are not reducing either the frequency or the cost of on-the-road crashes that result in insurance claims for vehicle damage,'' the study said.
Brian O'Neill, president of the IIHS and HLDI, said ``there is a perception out there that antilock brakes are going to allow you to stop on a dime in any crash situation. That is not true.''
The institute based its findings on a study of 95,000 insurance claims. It conducted surveys of seven General Motors Corp. vehicles comprising three 1991 and 1992 model groups, including the Chevrolet Cavalier/Pontiac Sunbird, Chevrolet Corsica/Beretta and Chevrolet Lumina/Pontiac Trans Sport. The study showed virtually no difference in claim frequency or losses between 1991, when the cars did not have ABS, and 1992, when they did.
Mr. Felrice, however, questioned the HLDI's use of only three car models-all from the same manufacturer-for its study.
``There are no Ford Escorts, Honda Accords, Geo Prizms or anything else,'' he said. ``The study doesn't look at trucks at all; trucks and sports vehicles have had ABS for a much longer time than passenger cars.''
ABS doesn't help as much on dry pavement as on wet, the study said, because maximum braking is easily achieved on dry pavement with or without antilocks.
Test demonstrations have shown that antilock brakes can prevent skids and spins during sudden stops. The new study did not explain why ABS didn't curtail the number and severity of accidents in everyday driving.
But previous studies indicate most accidents are not caused by uncontrolled skids, and that drivers either don't know how to use ABS, or take less care in driving ABS-equipped vehicles.
The HLDI study also cited the problem with driver inexperience. ``Drivers traditionally are trained to brake gently on a slippery road or to pump their brakes to avoid a skid,'' it said. ``But it's firm, continuous brake pressure that's required to activate antilocks, which should never be pumped.''
When a driver steps on the brake pedal, an antilock brake system recognizes when the wheels are about to lock up and cause the vehicle to skid. The system applies and releases the brakes several times a second, keeping the wheels turning and the vehicle under control.
Mr. Felrice agreed with the HLDI that lack of driver knowledge about antilock brakes may be a problem. This only points out the need to educate motorists about the proper use and capabilities of ABS, he said.
The HLDI study also doesn't divide crashes between frontal and rear-end, a distinction Mr. Felrice felt was important.
``In ABS, your frontal crashes will decrease, but rear-end collisions might increase because the person behind you might not have antilock brakes,'' he said. ``As more vehicles have ABS, that may cut rear-end crashes too.''
``Our concern is that a bad message not get out there about ABS,'' said Jay Minotas, insurance industry relations manager for GM. ``There are a lot of benefits to ABS, and we know they're there.''
Mr. O'Neill said he didn't know whether the HLDI study would cause the insurance industry to withdraw the discounts it offers drivers who have ABS.
``By our charter and tax status, we're not involved in the insurance business,'' Mr. O'Neill said. ``It's an individual choice for each insurer, and in some jurisdictions, the discount for ABS is actually mandatory.''
The insurance group also said it still believes cars and minivans should have antilock brakes. But it also said the study showed that they should be considered secondary safety devices, behind air bags and seat belts.
About 43 percent of all cars sold in the 1993 model year were equipped with ABS. But Congress has asked NHTSA to consider requiring them on all cars.
Although the insurance group examined only cars and minivans with antilock brakes on all four wheels, a preliminary government study showed that rear-wheel antilock brakes on trucks and sport-utility vehicles might reduce non-fatal off-road accidents.
That study, released last December, found that antilock brakes did little to prevent fatal or multi-vehicle accidents. But it found that vehicles with antilock brakes had 5 percent to 15 percent fewer fatal collisions with pedestrians or cyclists and fewer collisions with animals.
Meanwhile, NHTSA is accepting comments until March 7 on possible ABS requirements.
This report included information from the Associated Press.