Abstract
The first portion of this thesis examines bicyclist, automobile driver, vehicle, environmental, and roadway characteristics that influence cyclist injury severity in order to determine which factors should be addressed to mitigate the worst bicyclist injuries. An ordered probit model is used to examine single bicycle-single vehicle crashes from Virginia police crash report data from 2010 to 2014. Five injury severity levels are considered: fatalities, severe injuries, minor or possible injuries, no apparent injuries, and no injury. The results of this study most notably found automobile driver intoxication to increase the probability of a cyclist fatality six-fold and double the risk of a severe injury, while bicyclist intoxication increases the probability of a fatality by 36.7% and doubles the probability of severe injury. Additionally, bicycle and automobile speeds, obscured automobile driver vision, specific vehicle body types (SUV, truck, and van), vertical roadway grades and horizontal curves elevate the probability of more severe bicyclist injuries. Model results encourage consideration of methods to reduce the impact of biking and driving while intoxicated such as analysis of bicycling under the influence laws, education of drunk driving impacts on bicyclists, and separation of vehicles and bicycles on the road. Additionally, the results encourage consideration of methods to improve visibility of bicyclists and expectation of their presence on the road.
After the conclusion of the Virginia police crash data analysis, an analysis of nationwide bicycling under the influence laws and bicycle crashes was undertaken. Ultimately the nationwide data on bicycle fatality crashes from the fatality analysis reporting system proved to be insufficient to answer the questions posed, whether bicycling under the influence laws improve safety. As another outcome of the Virginia police crash data analysis a survey deployment project was completed, described in part two of this thesis. The purpose of this survey in part is to capture elements of bicycle data that were found to be lacking in the police crash reports. The survey development and analysis enhances the quality and quantity of available bicycle data in Virginia through the design and distribution of a survey throughout the state. The survey is particularly intended to capture bicyclist attitudes and perceptions of safety as well as bicycle crash data, as bicycle crashes are heavily under reported in police reported crash databases. The data is then analyzed using various statistical modeling techniques. The results of this survey most notably show very high levels of underreporting of bicycle crashes, only 12% of the crashes recorded in this survey were reported by the police. Additionally, the results of this work show that lack of knowledge concerning bicycle laws was associated with lower levels of confidence towards biking. Education could have an impact not only towards helping people be safer bicyclists on the road, but to bring more people on the road to start with. Additionally, it was found that when bicyclists act appropriately at traffic signals, by stopping they are less likely to be involved in car crashes. This could also be influenced by better education on how bicyclists are required to act on the road.
