Differences in geometry of pedestrian crashes in daylight and darkness

IntroductionPrevious studies have shown that increased risk in darkness is particularly great for pedestrian crashes, suggesting that attempts to improve headlighting should focus on factors that likely influence those crashes. The current analysis was designed to provide information about how details of pedestrian crashes may differ between daylight and darkness. Method: All pedestrian crashes that occurred in daylight or dark conditions in Michigan during 2004 were analyzed in terms of the variables included in the State of Michigan crash database. Additional analysis of the narratives and diagrams in police accident reports was performed for a subset of 400 of those crashes—200 sampled from daylight and 200 sampled from darkness. Results: Several differences were found that appear to be related to the characteristic asymmetry of low-beam headlamps, which (in the United States) distributes more light on the passenger's side than the driver's side of the vehicle. These results provide preliminary quantification of the how the photometric differences between the right and left sides of typical headlamps may affect pedestrian crash risk.Impact on IndustryThe results suggest that efforts to provide supplemental forward vehicle lighting in turns may have safety benefits for pedestrians.

Research Highlights
► When crossing at intersections, pedestrian crash risk differs in darkness compared to daylight.
► This difference occurs primarily with left-turning vehicles.
► No difference in risk was found with right-turning vehicles.