Traffic responsive signal control using fuzzy logic - a practical modular approach

In recent years Fuzzy Logic has been used to address a number of issues in traffic engineering. This paper presents an application designed to meet the demands of a traffic responsive signal control system operating at a single intersection in a concrete and practical way. Fuzzy logic techniques are incorporated into a modular system within which they provide effective support for the overall control method. This system reflects two fundamental aspects of traffic responsive signal control - the observation of the on-going traffic situation around the intersection, and the control of the traffic signals in a manner appropriate to the observed situation. Fuzzy logic provides a bridge between both of these essential functions by converting the large quantities of raw data emanating from the junction approaches into meaningful and succinct measurements relating to each signal group (or phase) which permit the control logic to make both second-by-second and cycle-by-cycle decisions about the apportionment of green time. The modular nature of this system allows it to be combined directly with the logic of conventional traffic responsive signal controllers. The extensive testing of the fuzzy logic controller carried out so far, using traffic simulation to model a variety of junctions and traffic situations, is to be validated by initial field trials in 1997.