Daylight Saving Time Changes Could Affect Drivers’ Safety: IIHS

Researchers are urging lawmakers to focus on proven ways to keep drivers and pedestrians safe during daylight saving time changes.

A new study suggests that the biannual clock changes for daylight saving time do not necessarily reduce the number of nighttime auto accidents, and may actually increase the risk of traffic problems.

The findings come amid growing concerns over the rising number of traffic fatalities deaths recorded in recent years. Since 2014, crash deaths have increased by 30%, and pedestrian fatalities have surged 83% since 2009. Experts warn the U.S. may be facing a road safety crisis, especially since most deadly accidents happen in the dark. 

Despite less than a quarter of all roadway travels occurring at night, nearly half of all crash fatalities, and 77% of pedestrian deaths happen during the darkest hours.

As a result of these fatality trends, the Insurance Institute for Highway Safety (IIHS) released a new report this month, examining whether shifts to or away from daylight saving time improve roadway safety. The findings indicate that changing clocks during daylight saving hours can shift ambient light at peak travel times, which can cause more auto accidents, resulting in a greater number of roadway fatalities.

IIHS president, David Harkey, submitted the written testimony to the U.S. Senate Committee on Commerce, Science, and Transportation on April 10, during a hearing held on whether to continue the annual switch between daylight saving time and standard time.

Harkey’s testimony looked at morning and evening crash patterns in the weeks surrounding daylight saving time changes and found that the evidence does not provide a definitive answer with regard to roadway safety on the effectiveness of turning back the clocks.

For example, pedestrian safety improves after “springing ahead,” while vehicle occupants fare better after “falling back.” Overall, there’s an annual decrease of 26 crashes involving pedestrian or bicyclist fatalities, but an increase of 29 crashes with vehicle occupant fatalities.

The results reinforce the idea that pedestrians and bicyclists face greater risks in low light, with changes in pedestrian crash deaths linked to daylight levels. No clear pattern was found for vehicle occupant fatalities.

The IIHS is urging policymakers to prioritize proven measures for pedestrian and bicyclist safety, including better lighting, caution signs, lower speed limits, safety cameras and road designs that slow down drivers.

“We at IIHS are alarmed by the rising toll of crashes on our nation’s roads and dismayed by an apparent lack of urgency to fix the problem. For this reason, we recently launched an initiative we are calling 30×30—a goal to reduce U.S. fatalities 30% by 2030,” Harkey said. “Achieving this reduction will require a concerted effort by all stakeholders. For our part, IIHS has laid out a series of concrete research, testing, and education actions that we are undertaking as part of our 5-year strategic plan.”

A previous 2020 study from University of Colorado researchers found a 6% increase in fatal car crashes the week after “spring forward,” while a 2023 study published in the journal Health Economics revealed fewer serious car accidents occurred during daylight saving time, with an increase happening during the autumn transition back to standard time.