The role of traffic circles in constrained urban environments

Abstract

Paper presented at the 33rd Annual Southern African Transport Conference 7-10 July 2014 "Leading Transport into the Future", CSIR International Convention Centre, Pretoria, South Africa.

National and international literature generally promotes traffic circles (roundabouts) as safe, efficient and cost effective alternatives to priority and signalised intersections. Research was conducted in eThekwini to evaluate the role of traffic circles in constrained urban environments. When priority intersections start experiencing high delays, local authorities are typically faced with the choice of replacing these intersections with traffic circles or traffic signals. The objective of the research was to quantify and compare the costs, environmental impacts (emissions), safety record and capacity of traffic circles versus traffic signals when the ability to expropriate additional land is both expensive and difficult. In such a scenario, are traffic circles able to be a competitive alternative to traffic signals? The research shows that, surprisingly, based on the above mentioned evaluation criteria, traffic signals still seem to offer both a safer and more cost effective option than traffic circles once the intersection reaches the traffic volumes that would warrant traffic signals.