Urban network traffic control

The optimum control of traffic in urban networks is an important requirement of city authorities as they seek efficient and sustainable transport. A feature of most urban networks is the high density of city streets with numerous road junctions, which require efficient control mechanisms if congestion is to be contained. Traffic signals have become the most widely used form of control in this context, with increasing sophistication in detection and real-time optimization providing new levels of efficiency. A changing policy background in many cities has also required greater emphasis in traffic control on the needs of public transport, cyclists and pedestrians, and on the need to minimize vehicle emissions. This paper provides an overview of problems, methods, systems and applications in the context of urban network traffic control, concluding with a look at future needs. The paper focuses particularly on signallized junctions within computer-controlled urban traffic control (UTC) systems, which are increasingly at the heart of traffic control in cities around the world.