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Study Finds Crash Avoidance Features Really Do Reduce Crashes

Study Finds Crash Avoidance Features Really Do Reduce Crashes

Autonomous braking and adaptive headlights yield biggest benefits

July 5th, 2012 by James Limbach of ConsumerAffairs in News

Some of those high-tech gadgets they're putting on cars really do make you safer. 

Insurance claim analyses by the Highway Loss Data Institute (HLDI) show that  collision avoidance systems -- particularly those that can brake autonomously -- along with adaptive headlights, which shift direction as the driver steers, show the biggest crash reductions. 

On the other hand, lane departure warning appears to hurt, rather than help, though it's not clear why, and other systems -- such as blind spot detection and park assist -- aren't showing clear effects on crash patterns yet.  

"As more automakers offer advanced technologies on their vehicles, insurance data provide an early glimpse of how these features perform in the real world," said Matt Moore, vice president of HLDI, an affiliate of the Insurance Institute for Highway Safety (IIHS). "So far, forward collision technology is reducing claims, particularly for damage to other vehicles, and adaptive headlights are having an even bigger impact than we had anticipated."Â 

Systems studied 

The crash avoidance systems studied were all offered as optional equipment. The automakers supplied HLDI with identification numbers of vehicles that had each feature, allowing HLDI to compare the insurance records for those vehicles with the same models without the feature. 

In each analysis, HLDI controlled for factors that could influence claim rates, including driver age and gender, garaging state and collision deductible.  

Forward collision avoidance 

Forward collision warning systems alert the driver if the vehicle is gaining on the traffic ahead of it so quickly that it is about to crash. Some of these systems also are equipped with autonomous braking, meaning the vehicle will brake on its own if the driver doesn't respond in time.  

Claims for the front-to-rear collisions that forward collision avoidance systems are meant to address are common under property damage liability (PDL) coverage, and HLDI found the technology reduces PDL claim frequency. Claim frequency under collision coverage, which includes many of the same crashes that fall under property damage liability but also a lot of single-vehicle crashes that these systems are not designed to address, was reduced but by a smaller amount. Some reductions also were seen for injury claims. 

Adaptive headlights 

Adaptive headlights respond to steering input to help a driver see around a curve in the dark. The headlights' horizontal aim is adjusted based on the speed of the vehicle, direction of the steering wheel and other factors so that the lights are directed where the vehicle is heading. 

Damage claims fell as much as 10 percent with adaptive headlights. That was surprising, since only about 7 percent of police reported crashes occur between 9 p.m. and 6 a.m. and involve more than one vehicle. An even smaller percentage are multiple-vehicle, nighttime crashes occurring on a curve, where adaptive headlights would be expected to have an effect. 

It's possible that other differences between the adaptive headlights and conventional ones besides steerability -- for example, in brightness or range -- may have played a role in reducing crashes with other vehicles. However, those differences weren't consistent among all vehicles in the analysis.  

Researchers had expected that the biggest effects from adaptive headlights would be on single-vehicle crashes reflected in collision coverage. Collision claim frequency did fall, but only by a little. However, injury claims of all types, both for injuries to occupants of the insured vehicles and to other road users, fell substantially for all but one make. 

Lane departure warning 

In contrast to the better-than-expected results for adaptive headlights, lane departure warning systems from Buick and Mercedes appeared to have the opposite of their intended effect. Both were associated with increased claim rates under collision and PDL coverages and for injuries to occupants of the insured vehicles. Although the increases were not statistically significant, the results suggest these particular systems aren't reducing overall crashes. 

Volvos with lane departure warning had lower claim frequencies under most coverages than Volvos without the feature, but those vehicles also had forward collision warning with auto brake, which more likely accounts for the benefits.  

IIHS researchers previously calculated that if all vehicles had lane departure warning, the technology could prevent or mitigate up to 7,529 fatal crashes, provided the systems worked as intended and drivers always responded appropriately. That potential stems from the large proportion of fatal crashes that are a result of a vehicle leaving the roadway. 

However, as a proportion of all crashes, not just fatal ones, drifting off the road is not common. That may help explain why no benefit has shown up so far in the claims data. The HLDI results also could point to problems with the current technology, which relies on cameras to track lane markings and thus isn't effective if the markings aren't clearly visible. 

HLDI has yet to look at lane departure prevention, which, unlike a warning system, actively keeps a vehicle in its lane and could have a very different impact on claims. 

"Just as forward collision warning systems that include autonomous braking cut crashes more sharply than those that don't, lane departure prevention systems that don't rely on a driver's response may hold more promise than the systems HLDI has looked at so far," says David Zuby, chief research officer at IIHS. "The lane departure prevention systems are newer and less common than the warning systems, so we'll have to wait for more data before we can look for a pattern there."Â