1. BACKGROUND The mighty Zambezi Drive, not very much unlike the great Zambezi River, is a major arterial in the north of Pretoria. It is a major road running in an east - west orientation that carries a very high volume of traffic, together with a substantial proportion of heavy vehicles. The travel speeds are also relatively high, typically faster than the posted speed limit of 80 km/h. The traffic enters Zambezi Drive from a number of side roads (tributaries) A comprehensive project was undertaken to improve traffic operations along Zambezi Drive. This paper addresses one very important component of this project, the proper co- ordination of traffic signal along the route.