UK Techniques for the Prediction of Capacities, Queues, and Delays at Intersections Without Traffic Signals

The UK Transport and Road Research Laboratory (TRRL) has been concerned for many years now with techniques for predicting capacities, queues and delays at non-signalised road junctions. A separate paper [1] has outlined the background to the development of current practices; the aim of the present paper is to amplify the results and to describe how the techniques have been drawn together in two computer programs ARCADY2 and PICADY2. The programs calculate capacities, queues and delays at roundabouts and major/minor junctions respectively. They use information about arriving (demand) flows and junction geometry, and provide traffic engineers with essential aids in the design of non-signalised junctions. They have been in widespread use by local authorities and engineering consultants in the UK for a number of years and are used to an increasing extent in other countries.