Issues with traffic signals

Abstract

Paper presented at the 23rd Annual Southern African Transport Conference 12 - 15 July 2004 "Getting recognition for the importance of transport", CSIR International Convention Centre, Pretoria, South Africa. In 2000, the National Department of Transport commissioned the redrafting of Volume 3, Traffic Signal Design and related chapters of the Road Traffic Signs Manual. The first draft was completed in April 2001 and has been in use since that date. Various changes to the design of traffic signals appear in this draft, requiring changes to the National Road Traffic Regulations. The changes to the Regulations were promulgated in September 2003. During the preparation of the document a number of issues arose that were not dealt with, mainly because the research necessary had not been undertaken. Most of the issues relate to the configuration of signal faces, and include amongst others the following: �� Traffic operations during right-turn phases are often inefficient because drivers are not able to anticipate the flashing green arrow and sometimes do not see it. �� The lagging right-turn phase has several advantages when compared with the leading right-turn phase, but its effectiveness is currently being limited due to the signaling system. There is a need to consider changes to the system. �� A protected-only right-turn phase is one in which the right-turn movement is allowed only when a green flashing arrow signal is indicated. A new signal face and road sign is now provided for this in the regulations. Experience with the signal face, however, has shown that while it serves this purpose, it does have a number of disadvantages. An alternative approach may be required and is discussed in the paper. This paper also addresses some alternative signaling methods. It is proposed that a research project be commissioned to properly investigate and evaluate both existing and alternative traffic signal systems.