Daylight Saving Time Influences on Fatal Road Crashes Vary by Light Conditions and Road User Type

A comprehensive study by the Insurance Institute for Highway Safety examines the impact of daylight saving time (DST) on road safety by analyzing fatal crash data from 2010 to 2019. The research focused on the contiguous United States, considering the 5-week periods before and after the biannual time changes in spring and fall. The findings reveal a distinct pattern: fatal crashes among motor vehicle occupants increased by 12% following the spring shift to DST, while decreasing by 7.1% after the fall change. Conversely, pedestrians and bicyclists experienced a 13% increase in fatal crashes after the fall change but a significant 24% decrease following the spring change.

These trends underscore the substantial influence of ambient light conditions on road safety. Specifically, lighter mornings in the fall lead to fewer pedestrian and bicyclist fatalities, whereas darker mornings in the spring increase these incidents. The study suggests that the adjustments in daylight not only shift the timing of peak traffic but also affect drivers’ visibility and reaction times, particularly impacting vulnerable road users like pedestrians and bicyclists.

Given these findings, the study advocates for enhanced infrastructure for pedestrians and bicyclists and the development of advanced vehicle technologies aimed at preventing crashes. This approach is crucial for adapting to the changing light conditions brought about by DST adjustments, ultimately aiming to improve overall road safety.