New IIHS Studies Suggest Lane-Departure Warning, Blind-Spot Detection Doing Their Job
Two studies published by the Insurance Institute for Highway Safety (IIHS) indicate that lane-departure warning and blind-spot detection—safety features that are standard or optional equipment on many light passenger vehicles—are preventing some thousands of potentially fatal crashes on U.S. roads.
Jessica Cicchino, IIHS vice president for research, conducted the studies as part of a series that evaluates different crash-avoidance features by looking at data from police-reported crashes. The data included in police reports includes information on the circumstances of a crash, making it possible to get some idea of how certain safety technologies might prevent or mitigate the accidents they’re designed to address. Cicchino's previous studies found that front crash prevention with autobrake can reduce the rate of front-to-rear crashes by 50%, and that rearview cameras can prevent approximately one out of six backing crashes.
According to the IIHS, results of the new study indicate that lane-departure warning lowers rates of single-vehicle sideswipe and head-on crashes, of all degrees of severity, by 11%, and lowers the rates of injury in crashes of the same types by 21%. The IIHS computes that if all passenger vehicles had been equipped with lane-departure warning, nearly 85,000 police-reported crashes and more than 55,000 injuries would have been prevented in 2015. The IIHS notes that the analysis controlled for driver age, gender, insurance risk level, and other factors that could affect the rates of crashes per insured vehicle year.
A simpler analysis, which did not take driver demographics into account, found that lane-departure warning cut the fatal crash rate by 86%. In that simpler analysis, the rate of all crashes was 18% lower for vehicles equipped with the feature, and the rate of injury crashes was 24% lower.
“This is the first evidence that lane-departure warning is working to prevent crashes of passenger vehicles on U.S. roads,” Cicchino said. “Given the large number of fatal crashes that involve unintentional lane departures, technology aimed at preventing them has the potential to save a lot of lives.”
The lane-departure warning feature is often included in a package of safety features, including front crash prevention, that’s included in a vehicle’s higher trim levels, or offered as a separate option. Thus, it was impossible for the study to separate the effects of those two features. However, the IIHS notes, a 2015 study of lane-departure warning on trucks in U.S. fleets found the technology cut the rate of relevant crashes nearly in half, and a study of Volvo cars in Sweden found a reduction of relevant injury crashes of 53%. The difference between these numbers and the considerably lower numbers reported in the IIHS study could be attributed to drivers’ tendency to turn off the lane-departure warning feature. The study also notes that the lane-departure warning is useless without an appropriate response from the driver. The IIHS recently examined 631 lane-drift crashes and found that 34% of the drivers were physically incapacitated.
The new study includes vehicles with optional lane-departure warning from six manufacturers: General Motors (GM), Honda Motor Co. (Honda), Mazda Motor Corp. (Mazda), Mercedes-Benz, Subaru Corp., and Volvo Group (Volvo). The automakers provided information about the presence of optional features on specific vehicles by vehicle identification number (VIN). Researchers used 2009-15 crash data from states that provided VINs of the crash-involved vehicles, making it possible to identify the vehicles and determine if they had lane-departure warning.
Cicchino included Fiat Chrysler Automobiles, GM, Honda, Mazda, Mercedes-Benz and Volvo vehicles, and used the same method, in studying blind-spot detection systems. In this case, she focused on crashes in which the vehicles were changing lanes or merging.
Controlling for other factors that can affect crash risk, blind-spot detection lowers the rate of all lane-change crashes by 14% and the rate of lane-change crashes with injuries by 23%, according to the IIHS.
“Blind-spot detection systems work by providing additional information to the driver,” Cicchino concluded. “It's still up to the driver to pay attention to that information and use it to make decisions. That said, if every passenger vehicle on the road were equipped with blind-spot detection as effective as the systems we studied, about 50,000 police-reported crashes a year could be prevented.”