The Effect of Raised Median on Traffic Flow and Its Remedial Measures: Case Study in Jimma Town

Abstract

The development of raised medians is an important access management technique commonly used in urban settings. It can be used to control or restrict mid-block left turns, U-turns or crossing maneuvers for implementing of alternative left-turn and U-turn movements. The insufficient design and installation of raised medians with respect of median width, spacing of median opening and length of median opening has an effect on the effective traffic operation by causing delay in travel time of through traffic movements as well as on traffic safety which generates traffic accidents between road users of both vehicles and pedestrians The objective of this research project is to develop guidelines that supplement the ERA manual for the design of operationally effective and safe raised medians and the use of alternative movements on urban roadways. To fulfill this goal the researcher has reviewed and synthesized national and international practices, conducted survey of traffic characteristics of both vehicular and pedestrian and field studies, explored the design issues relating to raised medians and alternative movements, and developed guidelines for future implementation of raised medians and representative alternative movements in Ethiopia. The results of this study provide recommendations on some critical design issues in the use of raised medians, including median widths, the techniques of landscaping and fencing of the medians, placement of median openings, and the median opening length.