Impact of Multilane Median Openings Zone on Travel Speed

Abstract

Thispaperaims to assess the impact of median openings zone of travel speed. Median openings or Midblock U-turn facilities are often constructed to provide motorists with detour option in circumstances where traffic conflict manoeuvres are eminent and prevalent. In previous studies, it has been shown that median openings will reduce the number of conflicts at relevant intersection.Hence median openings were built on multilane highways in Malaysia.Theirconstruction provoked debate on safety and traffic flow impediment issues. Based on the hypothesis that multilane median openings would cause travel speed reduction; an impact study was carried out at selected sites in Johor, Malaysia during daylight and dry weather conditions. Traffic volume, speed, and vehicle types were collected per road section for two directions continuously for eight weeks. The survey data were supplemented with highway design information culled from the Malaysian Public Works Departments manual. Travel speeds at median opening zone were estimated for both directional traffic flows. Results show significant decrease in travel speed of up to54.2% at the diverging section of the median openings zone. A slight drop of about 5% resulted from median openings zone at the merging section. The paper concluded that median openings zone facilities irrespective of their traffic conflicts minimisation merits will trigger significant travel speed reduction.