Congestion analysis and diagnosis in UTC networks

In the UK, networks of signals in urban areas are usually controlled by an Urban Traffic Control (UTC) system based either on fixed time plans derived using TRANSYT or by the traffic responsive system SCOOT. This paper describes simulation studies carried out to gain an understanding of the mechanism by which congestion spreads, and to investigate those situations and circumstances where SCOOT in its normal mode of operation loses effectiveness. Based on the result of the simulation a new measure of congestion has been developed called `Wasted Capacity´ derived from SCOOT data