OPERATIONAL ANALYSIS OF UNSIGNALIZED INTERSECTION AND ROUNDABOUT UNDER MIXED TRAFFIC FLOW CONDITION OF SELECTED INTERSECTIONS IN ADAMA CITY

Abstract

Urban traffic congestion is currently severe in most cities in the world due to economic and social development. Prevalently, Ethiopia is one of the countries that are in rapid economic development. This influences the travel pattern of the community from their origin to any destination. Adama is one of busy transportation center in Ethiopia. The city is situated along the road that connects Addis Ababa with Dire Dawa. A large number of trucks use this same route to travel to and from the seaports of Djibouti. A little attention has been paid to junctions and their capacities. There are a few studies conducted to assess the capacity of junctions in Adama. The main objective of this study was to evaluate operational performance on both unsignalized and roundabout junctions which are necessary for transport professional’s and governors to put tangible information for future traffic growth of Adama city. This thesis addresses the most important element of operational performance of unsignalized intersections and roundabouts traffic intersections in Adama City on capacity analysis. The methodology employed for this study was the quantitative descriptive research design which used quantitative data and analyzed using SIDRA 8.1 intersection software model. The movements of the vehicles were observed at three roundabouts and seven unsignalized intersections for a duration of two hours. The necessary geometric data for the analysis (average entry width, circulatory road width, number of entry and circulatory lanes, and island diameter), traffic movement data with vehicle characteristics and pedestrian volume were collected. The capacity analysis was done based on the gap acceptance method that is adopted by SIDRA 8.1 software program. Based on analysis results, Derartu Tulu roundabouts and six of selected unsignalized intersections i.e Mebrathayil,Sartera,Wonji,Tikur Abay and Alem Hotel junctions are currently serving in poor condition of level of service of F by having v/c ratio >1. Genda Gara and Medanihalem roundabouts are serving at their best operating condition having level of service A.The rest two unsignalized intersection Geda and Diamond Cafe have level of service of D and C respectively. The overall level of service of the unsignalized intersections and roundabouts are serving at poor level of service. Thus, after carrying out additional detail investigation and taking into consideration future traffic growth appropriate improvement should be made by concerned bodies