Research Papers

Motorcyclist Crash Responsibility: The Effect of Driver Age and Motorcycle Displacement

Version 1
Date added June 30, 2016
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Category 2016 CARSP XXVI Halifax
Tags Research and Evaluation, Session 4B
Author/Auteur Sacha Dubois
Stream/Volet Research and Evaluation
Slidedeck Presentation Only (no paper submitted)

4B - Dubois


Background/Context: In lay persons terms, motorcycle displacement (measured in CCs – cubic centimeters) is essentially a measurement of power. The higher the engine CCs the more powerful the motorcycle resulting in greater acceleration and speed. However, the vehicle will also be heavier, more difficult to control, and require longer braking distances.
Aims/Objectives: The goal of our study was to examine the effect of displacement on crash responsibility while considering motorcyclists’ age.

Methods/Target Group: We used data collected in the Fatality Analysis Reporting System for motorcyclists involved in a fatal crash in the U.S.A. between 1987 and 2009. To rule out the influence of alcohol and drugs, only motorcyclists with confirmed negative alcohol and drug blood tests were included. Because the majority of motorcyclists involved in fatal crashes were male (~97%), female motorcyclists were excluded from the analyses. We employed a case control design where cases had committed one or more Unsafe Driver Actions (UDAs), the proxy measure of responsibility; controls had no UDAs recorded. Odds ratios were computed via logistic regression examining the effect of motorcyclists’ age and motorcycle displacement (up to 1500 CCs, in 250 CC increments) on crash responsibility by any UDA committed, and also for the top three individual UDAs committed. Given the anticipated curvilinear effect of age and displacement, both linear and quadratic terms were included in the model. To explore the potential interaction between age and displacement (both linear and quadratic terms) the interaction terms were also included.

Results/Activities: Between 1987 and 2009 there were 12,047 male motorcyclists involved in a fatal crash whom tested negative for both alcohol and drugs and displacement data were available. Sixty-one percent of motorcyclists committed one or more UDAs (n=7,328). The top three individual UDAs were: Speeding (36%, n=4,369), Weaving (22%, n=22.4%), and Erratic Driving Behavior (7%, n=841). For motorcyclists aged 20, the odds of committing any UDA were greater by 19% (OR: 1.19; 95% CI: 1.07,1.33), 27% (OR: 1.27; 1.08,1.50), and 21% (OR: 1.21; 1.00,1.46) for displacement values of 500, 750, and 1000 CCs respectively, compared to 250 CCs. Similar odds were seen for motorcyclists aged 30, 40, and 50 years of age. By 60 years of age and older, higher displacement values did not significantly change the odds of committing any UDA. Of the top three individual UDAs the most pronounced changes in odds by displacement were seen for speeding. For motorcyclists age 20, the odds of speeding were greater by 95% (OR: 1.95; 1.75,2.17), 173% (OR: 2.73; 2.32,3.21), 175% (OR: 2.75; 2.29, 3.31), and 100% (OR=2.00; 95% CI: 1.59, 2.52) for displacement values of 500, 750, 1000, 1250 respectively compared to 250 CCs. This trend continued thru ages 30 to 60.

Discussion/Deliverables: Given these results education and legislative measures should be considered. For example, develop training interventions focusing on control, stability, and breaking differences given the vehicles greater weight and power. Legislatively, licensing tiers could be employed based on displacement and educational requirements.

Conclusions: Education and legislative measures could curb the trend seen between higher levels of displacement and crash responsibility.

Sacha Dubois