Identification of Causal Factors and Potential Countermeasures for Fatal Rural Crashes

Gary A. Davis
October 2005
Report no. Mn/DOT 2005-42


This project was divided into three phases. In phase 1 ten fatal run-off-road crashes were reconstructed from crash scene diagrams and investigation reports. We found evidence of excessive speed in five of these, and a failure to properly use seatbelts eight of the ten. For seven of these we found that barriers complying with Test Level 3 of NCHRP Report 350 would probably have stopped the crashing vehicle's encroachment. In phase 2 we developed a vehicle trajectory simulation model and used it reconstruct five fatal median-crossing crashes. We found clear evidence of excessive speed in one of these, and in three of the five the encroaching vehicle would probably have been restrained by Test Level 3-compliant barriers. In phase 3 five teams of traffic safety professionals reviewed accident reports from a sample of fatal rural crashes, with the aim of identifying possible causal factors and potential countermeasures. The most frequently identified causal factors were driver inexperience and failure to properly use restraints, while provision of rumble strips, improvements to roadsides or cross-slopes, and provision of guardrails or barriers were the most frequently-cited countermeasures.

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