Treatment of Narrow Medians on Four-Lane Rural Roadways

The objective of this study was to investigate alternatives to paved mountable medians that have been used in the past on sections of four-lane, partially controlled access roads where right-of-way is restricted. These mountable medians present obvious operational problems due to the 3-inch difference in height as compared to the through lanes. In addition, construction and maintenance problems are associated with mountable medians because of the height differential. A telephone survey of 16 states was conducted to determine their policy for separation of rural four-lane roads with partial control of access and narrow medians. Accident analyses comparing roads in Kentucky with and without mountable medians were also performed. Considering results from the survey and the accident analysis, it was determined that the flush median (rather than a mountable median) was an appropriate application for separation of rural four-lane roads with partial control of access and medians less than 20 feet wide.