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Status Report, Vol. 45, No. 5 | May 20, 2010 Subscribe

New estimates of benefits of crash avoidance features on passenger vehicles

Current crash avoidance features could prevent or mitigate about 1 of every 3 fatal crashes and 1 of every 5 serious or moderate injury crashes involving passenger vehicles. As many as 1.9 million crashes could be prevented or mitigated each year. This is the Institute's latest estimate of the safety potential of equipping all passenger vehicles with 4 crash avoidance features already on the market. The Institute shared its first effectiveness estimates in 2008 (see Status Report special issue: crash avoidance features, April 17, 2008). Now that more systems are on the road, the updated projections take into account limitations of current systems.

The fresh numbers follow the 2009 release of survey results indicating most early adopters are using the crash avoidance features in Volvos and Infinitis to be safer drivers (see "Luxury owners embrace systems to skirt crashes," Nov. 18, 2009).

The 4 new technologies the Institute studied include lane departure warning/prevention, forward collision warning/mitigation, side view assist (also known as blind spot detection), and adaptive headlights. In line with the 2008 study, a main finding is that lane departure warning has the potential to prevent or mitigate the most fatal crashes, while forward collision warning appears to have the greatest promise for reducing crashes of lower severity. Side view assist doesn't show as much potential simply because not as many serious crashes are relevant to this technology.

"This is a best-case-scenario estimate," explains Anne McCartt, the Institute's senior vice president for research. "We're not sure yet if the benefits will play out in everyday driving. A lot depends on whether the systems work as they're designed to and then whether drivers take the right corrective actions in response."

The Institute's earlier projections were based on ideal systems and ideal drivers. Researchers projected what future features might accomplish. This time around, they restricted the analysis to current systems and their limitations, including if bad weather affects operation. Crash data are from the National Automotive Sampling System General Estimates System and the Fatality Analysis Reporting System.

"The 4 kinds of crash avoidance technology we studied are relevant to about a third of crashes," McCartt points out. "These features are in some passenger vehicle models right now, and we expect them to go into more and more new passenger vehicles during the upcoming model years."

Annual crashes potentially prevented
or mitigated by type of system
 AllInjuryFatal
Forward collision warning1,165,00066,000879
Lane departure warning179,00037,0007,529
Side view assist395,00020,000393
Adaptive headlights142,00029,0002,484
Total unique crashes1,866,000149,00010,238
Percentage of crashes potentially prevented
or mitigated by crash avoidance features
 AllInjuryFatal
All passenger vehicle crashes5,825,000698,00033,035
Total unique crashes1,866,000149,00010,238
Percentage of crashes32%21%31%

Forward collision warning

More passenger vehicle occupants die in frontal crashes than in any other kind of crash. This technology detects when a vehicle is too close to one in front or to an object and then alerts the driver. In some cases this feature initiates braking and tightens safety belts if the driver doesn't respond promptly.

Forward collision warning has the potential to prevent or mitigate as many as 1.2 million crashes, or 20 percent of the 5.8 million police-reported passenger vehicle crashes that occur each year. The technology could prevent or mitigate as many as 66,000 crashes involving serious and moderate injuries as well as 879 fatal crashes each year. These estimates don't count injury crashes involving pedestrians or bicyclists. Some technologies in the works aim to safeguard these vulnerable groups. A new finding is that an additional 80,000 nonfatal injury crashes and 4,754 fatal crashes each year could be prevented or mitigated by systems that can detect pedestrians or bicyclists.

Lane departure warning

Head-on crashes, sideswipes, and crashes into off-road objects might be prevented by camera-based systems to detect when a driver begins to drift from a lane without signaling a turn. Then the system warns the driver to act, and sometimes is accompanied by a prevention feature that actively resists moving out of a lane. This technology has the potential to prevent or mitigate as many as 37,000 nonfatal injury crashes, 7,529 fatal crashes, and about 179,000 crashes a year overall. Current systems have some limitations, though. They don't operate at less than about 40 mph and won't give reliable warnings if lane markers are absent or obscured.

Side view assist

Mirrors on the rear and side help drivers keep track of nearby motorists, but blind spots on either side still allow adjacent vehicles to "hide." Side view assist uses sensors to detect vehicles approaching from behind and entering blind spots. Crashes that side view assist might address make up about a quarter, or 395,000, of lane-changing crashes per year. These involved 20,000 moderate-to-serious injury and 393 fatal crashes.

Adaptive headlights

These improve nighttime visibility on curves by pivoting as drivers steer around bends and corners. The count of relevant crashes amounts to roughly 142,000 per year, including nearly 2,500 fatal ones.

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