An Empirical Approach for Evaluation and Improvement of Roundabouts in Hyderabad

Abstract

Roundabouts are fairly common in busy areas to reduce the conflict points. This study is carried out to evaluate the performance of existing roundabouts to cater the present traffic and suggest improvements for the future traffic.   Due to rapid urbanization they may not work efficiently. In no-lane based heterogeneous traffic conditions performance is based on control delay and degree of saturation (V/C ratio). The main objective of this paper is to evaluate the performance of roundabout by assessing the Level of Service (LOS) using empirical models based on capacity and control delay and to make necessary improvements if required. For this study a total of 6 hour traffic data was used (out of 20 hours) from two roundabouts with 4-legged intersection in Hyderabad with different geometry and traffic characteristics. Data on geometric design elements including entry width, circulating width, weaving length and roundabout diameter measured through field survey during off peak period. Approach volume and entry delay were measured during peak and off-peak periods using video cameras. Evaluation is done using V/C ratio, control delay and LOS, based on the results of evaluation, micro simulation models were developed for poorly performing roundabout using VIISIM and enhancement is provided.