The impact of weather, road surface, time-of-day, and light conditions on severity of bicycle-motor vehicle crash injuries.

ABSTRACT

BACKGROUND: This study examined whether environmental variables including weather, road surface, time-of-day, and light conditions were associated with the severity of injuries resulting from bicycle-motor vehicle crashes. METHODS: Using log-binomial regressions, we analyzed 113 470 police reports collected between 2000 and 2014 in four U.S. states with environmental and injury severity information. "Severe" injuries included fatal and incapacitating injuries, and "non-severe" included non-incapacitating, possible or no-injuries. RESULTS: Light condition was significantly associated with the injury severity to the bicyclist with more severe injuries at dawn (RR = 1.62 [95%CI 1.35-1.94]) and during darkness (both lighted and unlighted roads 1.32 [1.24-1.40], respectively, 1.57 [1.41-1.76]) as compared to daylight. In these conditions of low visibility, risk was further increased during early morning hours before 7 am (1.61 [1.22-2.13]). CONCLUSIONS: Crashes in low light conditions and during early morning hours are more likely to result in higher injury severity.