Developing Guidelines for Median Barrier Installation: Benefit-Cost Analysis with Texas Data (05-2786)**
Shaw-Pin Miaou, Transmidas Consulting Services
Roger P. Bligh, Texas A&M Transportation Institute
Dominique Lord, Texas A&M University

Guidelines for the installation of median barriers presented in the American Association of State Highway and Transportation Officials’ (AASHTO) Roadside Design Guide have remained essentially unchanged for over 30 years. In recent years, the need for improved guidance has prompted several States to reevaluate their guidelines and has also precipitated a nationwide research project administered by TRB. The objective of the study, on which this paper is based, was to develop improved guidelines for the use of median barriers on new and existing high-speed, multilane, divided highways in Texas. The purpose of this paper is to present some modeling and benefit/cost analysis results from that study, with focus on the results from a particular data set developed under a “cross-sectional with-without” study design. The highways of interest were those classified as Interstates, freeways, and expressways with 4 or more lanes and have posted speed limits of 55 mph (88 km/hr) or higher. The models employed to estimate median-related crash frequencies and severities, including the Poisson-gamma and ordered multinomial logit models, as well as modeling results from a full-Bayes estimation method are presented. Based on the modeling results, a preliminary benefit/cost analysis, in conjunction with some sensitivity analyses, for developing the guidelines for concrete and high-tension cable barriers is described. The paper ends with a discussion on the limitations of this study and potential future extensions.