DYNAMIC CONTROL OF A MEDIUM SIZED TRAFFIC SIGNAL NETWORK

There are various levels of sophistication for co-ordination of traffic signals. These range from fixed time plans selected by time-of-day through dynamic selection of fixed time plans to full dynamic selection of cycle length, phase splits and offsets as in the Sydney Co-ordinated Adaptive Traffic (SCAT) system. A program has been developed for a medium sized co-ordinated signal network (20-40 signals) that automatically adjusts cycle length and trims offsets and phase splits appropriately, depending on the degree of saturation of traffic at critical locations. The basic phase splits and direction of offsets are currently selected by time-of-day, but the framework will allow further development for these to be traffic responsive. The control algorithms, which have their basis in classical traffic flow theory, and the method of traffic data collection are similar to those parts of SCAT and have been implemented on an Eagle CS300 system using a Nova mini-computer in Hobart, where the operation has proven to be satisfactory (a). The number of the covering abstract of the conference is TRIS No. 368448. (TRRL)