Roadway Median Treatments – Phase 1 and Phase 2

This research project examined relationships among crash rates, cross section design elements, and other operational attributes of multilane urban and suburban roadways in Arkansas. Crash rates for four cross section categories (roadways with no median, roadways with occasional left-turn lanes, roadways with continuous two-way left turn-lanes, and roadways with raised or depressed medians) were compared. Freeways were not considered. Crash histories were examined for cross section types, speed limits, volumes, widths of through lanes, presence of curb or shoulder, outer shoulder widths, median widths, and the densities of various types of access. Some variables were correlated, and it was suspected that such correlations can skew crash prediction models. Generally, the raised or depressed median group had slightly lower crash rates. The findings can help planners and designers when selecting the median type and cross section design for multilane roadways in rural areas that face future urban development, and in urban areas.