Traffic engineering solutions for minimizing delays and risks at roundabouts

Abstract

Introduction of a roundabout is a proven method of minimizing delays and risks at an intersection simply due to the reduction in number of conflict points, implementation of give way rule, single directional circulation and reduced speed due to the lateral displacement. However, there arestill opportunities and desires for improvements in reducing the delav and increasing the safety at roundabouts. The safety risk and delay is significant when vehicular volume is high. Roundabout performance can degrade if precautions are not taken eitherduring the design or the operation phases. Therefore this study is focused on seeking traffic engineering solutions to minimize the delav and risk of accidents at roundabouts to be implemented at design and construction stages. During the study, it was realized that a solution should be obtained through both literature reviews and data analysis. Therefore a comprehensive literature review was carried out on related sub topics. Crash and geometric data were collected for two normal roundabouts and analysed. Increasing the diameter of the central island up to the required level specified by the guidelines, decreasing the approach curve radius, elevating the circulating carriageway with respect to the approach carriage by introducing a ramp for the entering vehicles are proposed for the roundabouts as traffic engineering solutions.