Stopped-vehicle crashes result in hundreds of fatalities per year

June 3, 2021

Hundreds of people are killed and thousands are injured each year in crashes involving stopped or disabled vehicles that may not have stood out enough to alert drivers to the danger they pose, according to a new study commissioned by a company that makes enhanced hazard lighting systems.

Using federal crash statistics, transportation data analysis firm Impact Research estimated that 566 people were killed and 14,371 injured each year over 2016-18 in crashes on all types of roads involving a disabled vehicle in which visibility was likely a factor. The annual societal cost of those crashes totaled around $8.8 billion in medical payments, lost wages, and the less easily quantified costs of death or disability.

“This study identifies a part of the road safety equation that doesn’t get much attention, despite the size of the problem,” says David Zuby, executive vice president and chief research officer at the Insurance Institute for Highway Safety.

The federal crash databases include codes denoting crashes that involve stopped or disabled vehicles. To estimate how many of those might have resulted because the stationary vehicle wasn’t conspicuous enough, the authors analyzed detailed police reports from a subset of Florida crashes to determine the percentages of different types of collisions that involved a stopped vehicle that was too difficult for other drivers to see. Then they applied those percentages to the broader data set.

They found that 95 percent of these inconspicuous-vehicle crashes occur when a vehicle traveling down the roadway collides with a stationary one. However, more than half the deaths and almost 1 in 5 serious injuries occur when a vehicle strikes a pedestrian who is leaving, working on, or returning to a stopped vehicle. On average, this type of crash kills 300 pedestrians a year, a number that has risen by more than a quarter since 2014.

That increase comes amid a steady rise in pedestrian fatalities, generally. Overall, 6,205 pedestrians were killed on U.S. roads in 2019, up from just 4,109 a decade earlier. An earlier IIHS study found that around 800 pedestrians a year are killed on U.S. interstates and other freeways — about 18 percent of them due to a disabled vehicle.

“These crashes illustrate the potential value of stopped-vehicle-ahead warnings, which are already provided by some navigation apps and could be integrated to work with advanced driver assistance features and more advanced driving automation,” Zuby says. “They’re also a reminder of why we put so much emphasis on good headlights as a vital crash avoidance technology.”

Crashes like these could potentially be eliminated with vehicle-to-vehicle communication, which enables vehicles to wirelessly exchange information about their speed, location, and heading. But long before that technology becomes commonplace, several simpler countermeasures could help, the report suggests.

Earlier research indicates that improving hazard lights so they flash brighter and more frequently and are triggered automatically in the event a vehicle is disabled could reduce crashes. Nearly a third of the collisions in that study involved a stationary vehicle that had its hazards on. Emergency Safety Solutions, which commissioned the Impact Research report, makes one such enhanced hazard lighting system.

Adjustments to the “move over” laws that require drivers to change lanes to give police and emergency services vehicles more room to operate could also help, Impact Research concluded. Such laws are now in place in all 50 U.S. states. But first responders continue to be killed and injured in secondary crashes, prompting the U.S. Government Accountability Office to announce in June 2019 that it would conduct a study to review what might be done to make these laws more effective.

Better traffic management practices could also make a difference. Under one such policy, first responders dispatch two vehicles to every highway incident and use one vehicle primarily to shield the personnel working on the disabled vehicle from oncoming traffic, increasing the visibility of the scene with flares, safety cones and flashing lights.

However, more research is needed there, as well. The most recent Federal Highway Administration report on the subject was written in 2010, before many relevant technologies became available, and its authors were unable to identify specific traffic management procedures that were most effective in preventing secondary crashes.

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