Run-Off-Road Crashes: An On-Scene Perspective

Run-off-road (ROR) crashes, which usually involve only a single vehicle, contribute to a large portion of fatalities and serious injuries to motor vehicle occupants. In this study, the National Motor Vehicle Crash Causation Survey (NMVCCS) data collected at crash scenes between 2005 and 2007 is used to identify the ROR critical pre-crash event, assess the critical reason for the ROR critical event, and examine associated factors present in the pre-crash phase of the ROR crash. The effect of antilock brake system (ABS) and electronic stability control (ESC) on ROR crashes is also evaluated. The results show that over 95 percent of the critical reasons for single-vehicle ROR crashes were driver-related. The most frequently occurring category of critical reasons attributed to drivers was driver performance errors (27.7%) such as “overcompensation” and “poor directional control,” followed by driver decision errors (25.4%) such as “too fast for curve” and “too fast for conditions,” critical non-performance errors (22.5%) such as “sleeping” and “heart attack/other phys-ical impairment,” and recognition errors (19.8%) such as “internal distractions” and “external distractions.” With the presence of alcohol in the driver, as high as 46.9 percent of driver-related critical reasons for single-vehicle ROR crashes were driver performance errors. The logistic regression analysis shows that the most influential factors in the occurrence of single-vehicle ROR crashes were the factors “driver inattention,” “driver was fatigued,” and “driver was in a hurry.” In the NMVCCS crashes, for the vehicles equipped with both ABS and ESC, 7.5 percent ran off the road, while for the vehicles equipped with neither ABS nor ESC, 14.6 percent ran off the road. The odds of being involved in ROR crashes for the vehicles equipped with neither ABS nor ESC were 2.1 times greater than the odds for the vehicles equipped with both ABS and ESC. The combined effect of ABS and ESC systems on reducing the ROR crashes is significant, which is consistent with prior evaluation of the long-term effect of ABS and ESC based on the FARS and GES data. This study is the National Highway Traffic Safety Administration’s first effort in evaluating the effectiveness of crash avoidance technologies with the NMVCCS data.