New research from the Insurance Institute for Highway Safety (IIHS) shows lane departure warning and blind spot detection are preventing crashes on US roads.

Jessica Cicchino, IIHS Vice President for research, evaluated different crash avoidance features by looking at data from police-reported crashes. The police reports included information on the circumstances of a crash, making it possible to look specifically at the types of crashes that can be addressed by particular technologies, rather than just looking at general crash rates.

Cicchoni’s previous studies found that front crash prevention with autobrake cuts the rate of front-to-rear crashes in half and that rear-view cameras can prevent about one in six reversing crashes.

Results of the study indicate that lane departure warning lowers rates of single-vehicle, sideswipe and head-on crashes by 11%, as well as lowering the rate of injurious crashes by 21%. Therefore, if all passenger vehicles had been equipped with lane departure warning, approximately 85 000 police-reported crashes and 55 000 injuries could have been prevented in 2015. The analysis considered driver age, gender, insurance risk level and other factors that could affect the rates of crashes.

In a simpler analysis that didn’t account for driver demographics, it was found that lane departure warning cuts the fatal crash rate by 86%, the rate of all crashes was 18% lower, and the rate of injurious crashes was 24% lower.

“This is the first evidence that lane departure warning is working to prevent crashes of passenger vehicles on US 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 analysis uncovered direct benefits in the form of lower claim rates from lane departure warning. On many vehicles, lane departure warning is bundled with front crash prevention, making it impossible to separate the effects, as insurance data doesn’t include the type of crash. On the few vehicles studied that don’t bundle the feature, no benefits for lane departure warning have been found.

However, a 2015 study of lane departure warning on trucks in US fleets found the technology cut the rate of relevant crashes by nearly half, and a study of Volvo cars in Sweden found a reduction of relevant injury crashes of 53%.

Compared with those results, the new findings of an 11% reduction in all relevant crashes and a 21% reduction in injurious crashes are modest. IIHS says one reason may be that US drivers of passenger vehicles frequently turn off the lane departure warning. Researchers don’t know what percentage of the time lane departure warning was turned on in the earlier studies, but if drivers in a new study had kept the feature on all the time, the results would be in line with the benefits found in the earlier studies, Cicchino estimates.

Another factor affecting the size of the benefit is that lane departure warning requires an appropriate response from drivers, but researchers found that 34% of drivers in a lane-drift study had not been physically capable of making that appropriate response.

The study included vehicles from six different companies that had optional lane departure warning, General Motors, Honda, Mazda, Mercedes-Benz, Subaru and Volvo. The car companies 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 vehicles involved in crashes, making it possible to identify the vehicles and to determine if they had lane departure warning.

Cicchino used the same method to examine blind spot detection system, which provide a visual alert when an adjacent vehicle is in the driver’s blind spot. In this case, she focused on crashes in which the vehicles were changing lanes or merging. Fiat Chrysler, General Motors, Honda, Mazda, Mercedes-Benz and Volvo vehicles were included in the study.

Blind spot detection was found to lower the rate of all lane-changing crashes by 14% and the rate of lane change crashes with injuries by 23%.

“Blind spot detection systems work by providing additional information to the driver. It’s still up to the driver to pay attention to that information and use it to make decisions,” Cicchino said. “That said, if every passenger vehicle on the road was equipped with blind spot detection as effective as the systems we studied, about 50 000 police-reported crashes a year could be prevented.”