From 2007 through 2009, there were over 14,000 fatalities that resulted from opposite direction crashes (source: Fatal Analysis Reporting System, NHTSA). Nearly 80% of these crashes occurred on undivided roadways. Countermeasures, such as rumble strips/stripes, delineators, and barriers have proven to reduce both total crashes and serious injury crashes as reported in NCHRP Report 641; however, there is limited guidance on their specific performance. Improved guidance is needed on when and what type of countermeasure is appropriate, and what roadway factors may lead to higher opposite direction crash frequency rates. Additionally, guidance on the progression of countermeasures (i.e., from rumble strips/stripes to additional separation to the addition of barriers) and how these countermeasures could be applied on a systemic basis to proactively address opposite direction crashes is not well documented in AASHTO guidance. Although many opposite direction crash countermeasures have been studied individually, guidance on selecting from a wide range of opposite direction countermeasures does not exist. The median barrier for divided roads and centerline rumble strips for undivided roads have been the most studied countermeasures, but other countermeasures, such as reallocating lane width to create a small buffer median between opposing lanes, may be appropriate in some applications. A comprehensive guide on opposite direction crash countermeasures combined with a better understanding of what roadway factors increase opposite direction crash risk would aid transportation agencies in cost-effectively investing in countermeasures to reduce crashes on their road systems.
The objective of this research was to develop guidelines for the identification, prioritization, and selection of effective countermeasures to reduce or eliminate opposite directional crashes. The guidelines are intended for future possible adoption by the AASHTO Technical Committee on Roadside Safety as an update to the AASHTO Roadside Design Guide.
This project is complete and the final report has been published as NCHRP Research Report 995, "Guidelines for Treatments to Mitigate Opposite Direction Crashes."