AbstractSevere injuries among motorcyclists have been increasing over the past decade in Iowa. Motorcyclists account for only 0.44% of vehicle-miles traveled in the state, but make up 14% of all fatalities. Identification of high-risk drivers is needed to inform prevention activities. The purpose of this study was two-fold: 1) examine the predictors of a driver being charged in a motorcycle crash and 2) examine the relationship between driver traffic-related charge histories and non-collision and collision motorcycle crashes. Methods: Iowa Department of Transportation motorcycle crash data were linked to Iowa Court Information System data from 2011 to 2015. Drivers were classified into three groups: non-collision motorcyclists, collision motorcyclists, and other vehicle drivers. Frequency distributions of driver charge and conviction types were examined. A multivariable logistic regression model was built to study characteristics associated with driver charge status. Traffic-related charge histories of all the drivers were also examined. A GLM model with negative binomial distribution, adjusting for age and sex, was used to calculate the rate ratio of previous charges between different types of drivers. Results: A total of 7466 drivers were involved in motorcycle crashes during this study period; 2385 (31.9%) non-collision motorcyclists, 2586 (34.6%) collision motorcyclists, and 2495 (33.5%) other vehicle drivers. Charged motorcyclists were significantly more likely to be male, younger, under the influence of drugs or alcohol, not wearing a helmet, and have contributed a cause to the crash. The same was true for other vehicle drivers, with the exception of sex. Other vehicle drivers received the highest conviction rate (83.1%), compared to collision (68.1%) and non-collision (59.0%) motorcyclists. Administrative charges (e.g., no valid license) were the most common charge type among motorcyclists (36.5%), while failure-to-yield was most common for the other vehicle drivers (32.1%). Non-collision motorcyclists had a significantly higher number of charges during the three years preceding the crash compared to motorcyclists involved in collisions with other vehicles (Rate Ratio=1.05, 95%CI:1.00-1.10; p = 0.049). However, in motorcycle-motor vehicle collisions, the other vehicle drivers had fewer charges (Rate Ratio = 0.89; 95% CI: 0.84-0.94) during the three preceding years than the motorcyclists. Conclusions: Motorcyclists at high-risk of crashing may be identified through their history of traffic violations. Prevention approaches may include targeted law enforcement activities, training, and increased driver penalties for traffic violations. 

Dr. Cara Hamann  – is a Faculty Associate in Epidemiology and the Training and Education Core Coordinator for the Injury Prevention Research Center at the University of Iowa. Her main research interest is transportation safety, with a focus on vulnerable and high-risk road users, including motorcyclists, bicyclists, pedestrians, and novice and older drivers. Her work includes studies of adult and child bicyclist risk exposure and examination of charges and convictions in bicycle, motorcycle, and pedestrian crashes. She is also involved in teen driver safety and child passenger restraint research and is active in outreach and advocacy related to vulnerable road user safety. She has a PhD in epidemiology from the University of Iowa and a Master’s in Public Health from the University of North Texas Health Science Center..

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