Cross-median crashes are typically violent collisions with a high probability of multiple serious injuries and deaths. Previous research has shown that while cross-median crashes are not as common as other types of median-related crashes, they have a fatality rate that is disproportionately high. Many of these severe cross-median crashes can be prevented with adequate barrier protection. However, the decision of whether or not to use a median barrier should take into account the overall changes in the characteristics of median-related crashes that will result, including the frequency and severity of barrier impacts. There is a need for an analysis of the characteristics of median-related crashes and an investigation into the use of median barriers to identify changes to current standards, specifications, and procedures for median barrier need, selection, and placement that will result in the highest practical level of safety. Under this project, new guidelines were developed to assist highway engineers with the evaluation of median barrier need such that the highest practical level of median safety can be achieved. The recommended guidelines are based on analysis of median-related crashes in Texas. The crash data were used to develop crash statistical models for the various types of median-related crashes. Based on the estimates derived from the frequency and severity models and crash costs used by the Texas Department of Transportation (TxDOT), an economic analysis of median barrier need was performed. Guidelines for installing median barriers on divided, access-controlled freeways were developed as a function of average annual daily traffic (AADT) and median width. Guidance based on mean cross-median crash rate was also developed to assist engineers with evaluation of median barrier need on existing highway facilities.
Samenvatting