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Status Report, Vol. 48, No. 6 | August 8, 2013 Subscribe

Small overlap front crashes aren't just a U.S. issue, German study finds

Small overlap crashes account for a quarter of frontal crashes of all severities in Germany, a new study of insurance claims indicates. The finding is in line with IIHS research and adds more evidence that the Institute's newest vehicle ratings program addresses problems seen in real-world collisions.

Small overlap front crashes involve an overlap of as much as 25 percent of a vehicle's front end. The Institute's 40 mph small overlap front test is designed to replicate what happens when the front corner of a vehicle collides with another vehicle or an object. Introduced in 2012, the test is especially demanding of safety belt and airbag systems. IIHS is the only organization that currently includes a small overlap test in its crash test program providing consumers with comparative vehicle safety information (see "Small overlap crashes: New consumer-test program aims for even safer vehicles," Aug. 14, 2012).

In an attempt to quantify the problem in Germany, researchers at the German Insurers Accident Research (UDV) arm of the German Insurance Association analyzed insurance claims data to determine the prevalence of small overlap front crashes in relation to other crash configurations and identify the characteristics of these crashes and the patterns of injuries that occur in them.

Researchers examined claims data for 3,242 crashes involving passenger cars in Germany during 2002-09. All of the crashes in the database involved personal injury claims and vehicle damage costs of 15,000 euros or more ($19,000). More than half were frontal impacts. Small overlap crashes accounted for about 25 percent of frontal crashes and 15 percent of all crashes.

In a 2009 IIHS study of vehicles with good ratings for frontal crash protection, small overlap crashes accounted for nearly a quarter of the frontal crashes involving serious or fatal injury to front seat occupants (see "Crashes in the real world don't always mirror tests, so new frontal tests merit exploration," March 7, 2009).

In the German study, nearly two-thirds of car-to-car small overlap front crashes occurred on rural roads, with 37 percent on or near a curve. Looking at circumstances, 40 percent of crashes happened as drivers turned off the road or turned into or crossed a road. Nearly a third of the crashes were classified as "driving accidents" involving driver error. Of these, 74 percent took place near a curve.

"This gives reason to believe that a collision with a small overlap often happens because the party responsible for the [crash] gets into the oncoming lane unintentionally as a result of a driving error or due to inappropriate speed," the authors say. They note that crash avoidance systems might help to prevent some of these crashes.

Looking at injury patterns, small overlap crashes resulted in more lower extremity injuries than other frontal crashes. About 40 percent of all serious injuries (Abbreviated Injury Scale of 3) were to drivers' lower legs and feet. In contrast, only 24 percent of drivers in large overlap crashes had these injuries. What's more, drivers injured in small overlap crashes were nearly twice as likely to be unable to work for three months or longer as drivers in large overlap crashes.

"In the small overlap cases, which were more costly, the high costs involved were demonstrably attributable to complex foot injuries of the drivers involved that take a long time to heal," the authors note.

In the IIHS small overlap front test, dummy injury measures indicate that lower leg and foot injuries would be likely in many new vehicles. One of these is the Mercedes-Benz C-Class. The 2012 C-Class was among the 11 luxury/near-luxury cars IIHS evaluated in its inaugural round of tests. The C-Class earned a poor rating overall, including poor for lower leg and foot protection. Intruding structure caused the dummy's right foot to become wedged beneath the brake pedal. Intrusion into the footwell also was a problem for the Acura TSX, BMW 3 Series, Lexus IS 250/350 and Lexus ES 350. All earned poor ratings for lower leg and foot protection.

Since then, manufacturers have been making design changes to improve protection in small overlap front crashes. Initially, the Institute's new test raised questions among some automakers about its relevance to the types of crashes that happen outside the U.S.

Findings of the UDV study of crashes in Germany confirm that the small overlap crash problem isn't unique to the U.S. The authors conclude that crashes "involving a small overlap are at least as relevant as [crashes] involving a large overlap in the damage claims of insurers" and justify "efforts to implement countermeasures."

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