SUBURBAN HIGHWAY CROSS SECTIONS: MEDIAN VERSUS TWO-WAY LEFT-TURN LANE DESIGNS. FINAL REPORT

The purpose of this study was to examine the existing state of the art with regard to the selection of a roadway cross-section for a suburban arterial road. The goal was to develop guidelines to choose between alternative treatments in different situations with respect to land use, traffic volume, travel speed, etc. The primary focus of this research was on arterial highways in developing suburban areas, and two alternative treatments -- nontraversable medians and two-way left-turn lanes (TWLTLs). Several mathematical models were examined, but were found to be not universally applicable. The following investigations were performed to gain additional information: (1) a survey of highway design engineers of different state departments of transportation to identify their experience and preference; (2) an analysis of accidents on Tennessee highways with TWLTLs and medians, respectively; and (3) an analysis of traffic delay on road segments with a TWLTL and a median, respectively, using the simulation model known as NETSIM.