CAPACITY AND FLOW BREAKDOWN ON UK MOTORWAYS

With continued increases in traffic demand, congestion is now recurring on many sections of the UK motorway network in peak periods. This paper describes a large UK study undertaken by the University of Southampton for the UK Transport Research Laborator aimed at understanding and predicting motorway capacity and the f breakdown phenomenon. Such an understanding of fundamental parameters is clearly of importance if possible improvement measu are to be assessed and prioritised. The study was based on the video-based collection, compilation and statistical analysis of a large traffic database covering flows, composition, speeds, densities, headways and lane changing at some fourteen motorway sections suffering from recurrent congestion. The paper summaris the results of the study including predictions of motorway capaci merge capacity and flow breakdown occurrence. The paper conclude with a discussion of committed proposed improvements to motorway operations in the UK, including motorway widening, motorway tolli traffic management and control, and new advanced information syst (a)