The debate over Daylight Saving Time's impact on road safety drew fresh attention April 10, when David Harkey, president of the Insurance Institute for Highway Safety (IIHS), testified before the U.S. Senate Committee on Commerce, Science, and Transportation. Addressing lawmakers, Harkey emphasized that changing the clocks twice a year does not appear to be a major factor in America’s road safety crisis.
“Whatever you decide to do about the clock, I hope you will also consider actions to keep pedestrians and bicyclists safe, especially after sundown,” Harkey said in his written testimony.
Harkey placed the discussion in the context of a troubling national trend: traffic fatalities surpassed 42,000 in 2022, marking a more than 30% increase since 2014. To address the crisis, IIHS has launched its 30x30 initiative, which aims to reduce crash fatalities by 30% by 2030.
A recent IIHS study analyzed crash patterns around the time changes and revealed a nuanced picture. Pedestrian deaths tend to fall when the country switches to Daylight Saving Time in spring, while vehicle occupant deaths rise. In the fall, as standard time resumes, the pattern reverses -- vehicle occupant fatalities decline and pedestrian deaths increase.
Taken together, these seasonal shifts result in a small net effect: an annual reduction of 26 pedestrian or bicyclist fatal crashes and an increase of 29 vehicle occupant fatal crashes. The variation in pedestrian deaths is directly linked to changes in daylight hours, while no clear trend was found for vehicle occupant fatalities.
“If you are looking for concrete guidance on whether to keep the current twice-yearly time changes, … the evidence does not point definitively one way or another,” Harkey said. “What our study does reinforce is that pedestrians and bicyclists are at greater risk in low light conditions.”
To address these risks, Harkey urged lawmakers to prioritize proven safety interventions. These include infrastructure enhancements such as improved crosswalk lighting, pedestrian hybrid beacons and rectangular rapid flashing beacons. In addition, reducing vehicle speeds through lower speed limits, speed cameras and road designs that encourage slower driving can significantly improve safety for vulnerable road users.
