Recent research has shown that traditional safety evaluation methods have been inadequate in accurately determining the effectiveness of roadway safety measures. In recent years, advanced statistical methods have been utilized in traffic safety studies to more accurately determine the effectiveness of roadway safety measures. These methods, particularly hierarchical Bayesian statistical techniques, have the capabilities to account for the shortcomings of traditional methods. Hierarchical Bayesian modeling is a powerful tool for expressing rich statistical models that more fully reflect a given problem than a simpler model could. This paper uses a hierarchical Bayesian model to analyze the effectiveness of two types of road safety measures: raised medians and cable barriers. Several sites where these safety measures have been implemented in the last 10 years were evaluated using available crash data. This study analyzes the effectiveness of raised medians and cable barriers of roadway safety by determining the effect each has on crash frequency and severity at selected locations. The results of this study show that the installation of a raised median is an effective technique to reduce the overall crash frequency and severity on Utah roadways. The analysis of cable barriers showed that cable barriers were effective in decreasing cross-median crashes and crash severity.



College and Department

Ira A. Fulton College of Engineering and Technology; Civil and Environmental Engineering



Date Submitted


Document Type





Bayesian, cable barriers, raised medians, safety, transportation