A mixed logit analysis of two-vehicle crash severities involving a motorcycle

•The factors affecting two-vehicle motorcycle crash severity outcomes are examined.•A random parameter model is used to account for the limited police-reported information on motorcycle conspicuity.•A wide range of factors significantly influences crash severity outcomes.•Roadway surface condition, clear vision, speed limit, light conditions and helmet use are among the key factors influencing severe injury crashes.•Five factors were found with non-uniform effects on minor and lower severity outcomes.

Using motorcycle crash data for Iowa from 2001 to 2008, this paper estimates a mixed logit model to investigate the factors that affect crash severity outcomes in a collision between a motorcycle and another vehicle. These include crash-specific factors (such as manner of collision, motorcycle rider and non-motorcycle driver and vehicle actions), roadway and environmental conditions, location and time, motorcycle rider and non-motorcycle driver and vehicle attributes. The methodological approach allows the parameters to vary across observations as opposed to a single parameter representing all observations. Our results showed non-uniform effects of rear-end collisions on minor injury crashes, as well as of the roadway speed limit greater or equal to 55 mph, the type of area (urban), the riding season (summer) and motorcyclist's gender on low severity crashes. We also found significant effects of the roadway surface condition, clear vision (not obscured by moving vehicles, trees, buildings, or other), light conditions, speed limit, and helmet use on severe injury outcomes.