Performance Evaluation of Roundabouts and Stop Control Intersection in Nekemte Town, Oromia Region, Ethiopia

Abstract

Roundabouts and stop control intersections are generally considered to be essential points within the urban road network. Currently, the operational level of a Nekemte town road network indicates that traffic police are on duty at peak hours to regulate traffic operations. Hence, this study on the performance evaluations of roundabouts and stop control intersections in Nekemte town helps to study and advocate performance improvement measures for possible future concerns during junction planning, designing, and traffic operational tasks in the town. In this research, the three existing roundabouts with three, four, and five approaches and three stop control intersections on the major road corridors of the town which represent significant traffic and pedestrian activities have been selected. The research focused on analyzing the performance measures, vehicle distribution, pedestrian interaction, and travel patterns at town intersections. The methodology employed in this study was the quantitative and qualitative descriptive approach to research design. The necessary geometric data required for the analysis were collected from each intersections. Traffic movement data with vehicle characteristics and pedestrian volume were collected from the study area with a video camera followed by manual extraction and in case of the video camera was inappropriate to install and video recording was not allowed, manual recording using a skilled field observer was involved. The analysis and evaluation were by SIDRA INTERSECTION 8.0 (Signalized and unsignalized Intersection Design and Research Aid) on the basis of 2010 highway capacity manual. The result of the analysis for the selected samples of roundabouts and stop control intersections of Nekemte town indicated that; Second Round (Marfata Lammaffaa) roundabouts and near to Wegagen hotel two-way stop control intersection is congested for existing traffic flow experiencing beyond capacity, excessive delay, and very long queuing at peak hour. Based on the design life demand analysis, the result of analysis indicates that most of the intersection worst movement will be forced flow or congested after three to five years except near to the Benori pension all-way stop control intersection. The inadequacy of geometric elements, high proportions of the pedestrian’s volume, a high proportion of motorcycle taxi (Bajaj), and relatively high composition of left turn and U-turn movement of vehicle was the root cause for the intersections to have poor performance. Also, improper traffic marking and traffic sign indirectly influences the performance level of these intersection. The performance level of the roundabouts will be improved by revising with a design requirement of modern roundabouts specifications. While near to Wegagen hotel two-way stop control intersection will be improved by upgrading to signalization. Town public bus transport system should be practiced and some percentage of motorcycle taxi (Bajaj) should be rerouted from major routes to increase the capacity of the intersection.