This study examines the trends, characteristics, as well as contributory causes associated with run-off-road (ROR) and non-run-off-road (NROR) crashes. Likelihood ratios of these causes for ROR crashes with respect to NROR crashes are assessed using the Bayesian Statistical Approach. Nighttime, weekends, adverse weather, rural area, gravel and curved roads, higher speed limits, wet and icy road surface, and utility vehicles are found to be the common characteristics of ROR crashes. Fell asleep, ill or medical condition, driving under the influence, too fast for conditions, tires and wheels, strong winds, freezing rain, shoulders, ruts, holes, and bumps are found to have the greatest likelihood ratios and as such have a greater role in contributing to ROR crashes than NROR crashes.
