Alcohol-involvement continues to be a prominent factor in motorcycle crashes. Automobile-driver drinking and driving has been researched extensively, and the relationship between drivers' blood alcohol concentrations (BAC) and crash risk is well-understood. Unfortunately, our current understanding of the effects of BAC on motorcycle operation is insufficient. This project examined a variety of approaches by which the effects of alcohol on motorcycle rider impairment and crash risk can be measured. A two-volume report was prepared.

Vol. I: Synthesis Report on Alternative Approaches with Priorities for Research
(Report # DOT HS 810 761)

Various research methods were reviewed in the literature (see Volume II, Literature Review), and an expert panel was convened for detailed discussion and prioritizing of possible methods. Different methods were grouped by assessed scientific value and estimated cost. Generally, it was determined that methods using existing data would be the lowest cost, but would also have the lowest scientific value. Conversely, the best data will come from new, more detailed data collection methods specifically defining the population-at-risk. Methods examined include “field” studies that collect actual highway data, and “simulator” or “closed course” studies that collect data in a controlled setting. Priorities for future research were assigned to each methodology. The highest priority methodologies were assigned to “Contemporary Case Control,” Simulation and Induced Exposure studies.

Vol. II: Literature Review Report
(Report # DOT HS 810 762)

A literature search was performed that focused on: (1) past research on impaired motorcycle operation; (2) past research methodologies used to understand alcohol’s effects on human performance, including laboratory simulation, closed-course operation, self-report surveys, crash investigation, and analysis of archival crash data; and (3) methodologies used to measure exposure in populations-at-risk, including roadside surveys. The literature review revealed a dearth of research on impaired motorcycle operation relative to the objectives of this project. The collection of BAC data from on-road non-crash-involved motorcycle riders was the most significant need identified from the review. A total of 143 reports and Web sites were reviewed for this project and described in detail in Appendices A and B of this report. Sixty-one of these are cited in the two volumes of this report. An in-house study of fatal motorcycle crashes was also conducted and discussed in this report.