Differences in Motorcycle Conspicuity-related Factors and Motorcycle Crash Severities in Daylight and Dark Conditions

Previous studies in the United States and internationally suggest that low motorcycle conspicuity, or the inability of the motorcyclist to be seen by other road users, is an important factor associated with the risk of motorcycle crashes. However, there has been limited research on motorcycle conspicuity in the United States in the past two decades, while at the same time, there has been a renewed interest from states in increasing motorcycle conspicuity and motorist awareness. Using motorcycle crash data for Iowa from 2001 to 2008, this paper examines the distribution of conspicuity related factors that could potentially relate to a collision between a motorcycle and another vehicle in daylight and dark conditions using contingency table analysis. Shaheed, Zhang, Gkritza, Hans 2 This paper further examines the distribution of collision configurations (such as “nonmotorcycle” being “at-fault” in rear-end collisions, angle crashes, and sideswipe crashes) and factors (related to “non-motorcycle” vehicle drivers) potentially related to not seeing motorcyclists for different motorcycle crash severity outcomes using contingency table analysis. Finally, this paper develops a multinomial logit model to investigate the effect of potential motorcycle-conspicuity related factors on motorcycle crash severity outcomes. The results from the model show that angle crashes (“non-motorcycle” turning left), rear end crashes (“nonmotorcycle” hitting “motorcycle”), light conditions, failure to yield ROW (right of way) by nonmotorcycle drivers, light conditions and other variables played significant roles in motorcycle crash-injury outcome. The limitations of examining motorcycle conspicuity by analysis of crash data are also discussed.