— Before you turn off that pesky lane departure chime or blind spot warning light, consider this: Such crash-avoidance technology can lower collision rates by double-digit percentages, according to new studies by the Insurance Institute for Highway Safety.
The agency analyzed police-reported crash data, confirming reported vehicle identification numbers with a handful of participating automakers to determine which crashed cars had the two systems. Controlling for demographics, IIHS found lane departure warning systems reduced rates of single-vehicle, sideswipe and head-on crashes by 11 percent, while blind spot warning systems reduced the rate of all crashes involving lane changes by 14 percent.
If every passenger car had lane departure warning, IIHS says nearly 85,000 police-reported crashes wouldn't have happened in 2015. It's the "first evidence that lane departure warning is working to prevent crashes of passenger vehicles on U.S. roads," said Jessica Cicchino, vice president of research at IIHS, in a statement.
Meanwhile, some 50,000 police-reported crashes could be prevented each year if all cars had blind spot warning systems, she added.
But the potential for crash prevention may seem modest given how IIHS found in 2016 that another major safety technology, forward collision warning with automatic emergency braking, could reduce rear-end crashes by 39 percent. Still, researchers suspect the results for lane departure warning don't reflect the technology's full potential. Many drivers turn it off, IIHS notes, and a large portion of lane-drift crashes occur when drivers fall asleep or get ill — conditions that limit the effect of a warning.
Insurers have yet to correlate lower claim rates for vehicles with lane departure warning systems, in many cases because automakers bundle them with other active safety features, so it's difficult to isolate the effects. But Cicchino thinks that if all drivers with the feature simply kept it on, crash-prevention rates could be much higher.
How much? Try a reduction of 179,000 crashes each year. That's the number of crashes where lane departure warning is relevant, according to a 2010 estimate by IIHS that assumed "lane departure warning worked perfectly and drivers left it turned on," spokesman Russ Rader said.
Lane departure warning entered the U.S. market in pricey luxury models more than a decade ago, but it's now offered on cars as cheap as the Toyota Yaris and Honda Fit. Many systems now incorporate steering assist to nudge you back from the dividing line or even center your car in its lane altogether. Blind spot warning systems, now standard on mass-market cars like the 2018 Hyundai Sonata, have also seen a similar trickle-down, with assistive steering on some models as well.
IIHS didn't distinguish crash reductions for warning systems with steering assist, however. The study only looked at crash reductions for "the overall feature," Rader told .
"We haven't been able to isolate the more advanced lane departure systems yet," he said.
It remains to be seen if the research will prompt the agency to factor lane departure or blind spot warning systems into its model-specific safety awards. It's the first time "in the U.S. that we have established data that lane departure warning works, so it's possible in the future, but [there are] no plans right now," Rader said.
Automatic braking, which virtually the entire auto industry has pledged to make standard by 2022, gets a dynamic evaluation as part of the agency's crash tests.