UK techniques for the prediction of capacities, queues, and delays at intersections without traffic signals.

This paper extends some of the results obtained by TRRL on the prediction of capacities, queues, and delays at non-signalised intersections, and describes how these techniques have been combined in TRRL's ARCADY2 and PICADY2 programs. These programs calculate capacities, queues, and delays at roundabouts and major/minor road junctions, respectively. The paper presents the empirically-based UK capacity relationships for non-signalized intersections, which are particularly simple to apply, as they require only knowledge about the junction geometry and the flows of arriving vehicles. The use of the time-dependent queuing delay relationships described is fundamental to the accurate appraisal of busy road junctions. The paper describes the operation, capabilities, and availability of the programs ARCADY2 and PICADY2, which both use these relationships and enable these queue and delay formulae to be applied conveniently in an extensive range of practical situations. Thus they provide traffic engineers with essential aids in the design of non-signalised intersections. They have been widely used by local authorities and traffic engineering consultants in the UK for a number of years, and they are being used increasingly by other countries.