Towards a better understanding of modern roundabouts

Abstract

The use of the modern roundabout in South Africa as an alternative form of intersection control is gaining popularity with road authorities. There are however groups within the road user fraternity, and road authorities, who have the perception that roundabouts in South Africa do not have the benefits (safety and capacity) that have been determined internationally, both for vehicle and non-motorised transport users. A recent survey of 37 roundabouts in the Western Cape has confirmed that there is a lack of application of design standards and an inconsistent approach to the design of roundabouts. This inconsistency applies to both single- and multi-lane roundabouts in urban and rural areas. The purpose of this paper is twofold: to highlight what are some of the elements of the roundabouts that could be contributing to the perception relating to safety and to increase the designer’s awareness of the interacting nature of the different design elements. These elements will be compared to design guidelines developed in several countries including Australia, Germany, United Kingdom and United States of America. The goal, beyond this paper, is to develop guidelines for the design and implementation of roundabouts in the Western Cape.