This paper aims to provide a starting point for the future research on the application of state space theory to traffic gating and traffic control. It begins with an introduction to state space theory, and an outline of its applications to transport in general. There is then an in-depth discussion of its applications to congestion control, especially for traffic signal control in congested traffic situations. A range of transport, safety and environmental objectives is listed, but a compromise may have to be made in their selection, because some of them conflict. At present, most signal control methods aim to ease or prevent congestion, and few directly handle queue management in congested situations. raffic jams are usually triggered by the interaction between at least two queues. Four types of pre-planned measures for congestion control are discussed, and three main groups of theoretical traffic control studies are reviewed. The following contemporary urban traffic control systems, covering several different approaches, are described: (1) SCOOT (UK); (2) PRODYN (France); (3) OPAC (USA); (4) UTOPIA (Italy); (5) SAGE (France); (6) STAUKO/VERON (Germany); (7) SCATS (Australia). Some conclusions and recommendations are presented.
Abstract