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Benefits of daytime running lights

This study evaluated the effects of daytime running lights (DRLs) on two-vehicle, head-on crashes of passenger vehicles during daylight, dawn, and dusk. Two control dimensions were used: type of crash (the control being single-vehicle crashes) and light condition (the control being darkness). The data analyzed were U.S. fatal crashes for 1994 (during which time fewer than 1% of passenger vehicles were equipped with DRLs), 1999, 2004, and 2009 (during which time about 40% of passenger vehicles were equipped with DRLs). The results indicate that over the period examined (which had a large increase in the installation of DRLs), fatal, two-vehicle, head-on crashes (as percentages of singlevehicle crashes) were reduced more in daylight, dawn, and dusk than in darkness. Based on the present data, it is estimated that in 2009, DRLs reduced fatal, two-vehicle, head-on crashes by 8% in daylight and 28% in dawn and dusk.