Economics of traffic signals

The decision as to whether to install traffic signals or not is often based on a need to manage traffic and pedestrian conflicts at peak periods. Rarely is account taken of the economic impacts of traffic signals and how these may change as a result of varying traffic compositions, journey purposes and time of day. Using actual traffic data from selected junctions in London this paper addresses this failing and concludes that in the right place and at the right time traffic signals can provide significant economic benefits but in certain circumstances there are greater benefits from switching traffic signals off.