The effectiveness of Daytime Running Lights for passenger vehicles

  • Published: U.S. Department of Transportation, National Highway Traffic Safety Administration (NHTSA); Report number DOT HS 811 029, 2008
  • Authors: Wang J-S
  • Date Added: 25 Jan 2014
  • Last Update: 25 Jan 2014
  • Format: pdf


To evaluate the effects of daytime running lights (DRLs) against three types of target crashes:

  1. Two-passenger vehicle crashes excluding rear-end crashes

  2. Single-passenger vehicle to pedestrians/cyclists crashes

  3. Single-passenger vehicle to motorcycle crashes.


Each crash type was examined at three crash severity levels – fatal, injury, and all severity. The basic approach was a control-comparison analysis of real-world crash involvements for DRL-equipped vehicles and non-DRL vehicles. Ratio of odds ratios were used to derive the DRL effects and a 95-percent confidence interval was used to infer statistically significant conclusions. The Fatality Analysis Reporting System (FARS) and the State Data System were the crash data sources used for this analysis.

Key Findings:

  • The analysis found that DRLs have no statistically significant overall effects on the three target crashes.

  • When combining these three target crashes into one target crash, the DRL effects were also not statistically significant.


NHTSA, FARS, State data, daytime running lights, DRL, ratio of odds ratios, simple odds, statistical analysis.


The summary of results shows the trends identified. These are not reported in the abstract summary due to the lack of significance at the 95 percent level.