The application of tolls to the UK's motorway system is expected to put pressure on the remainder of the network which is mainly single carriageway. An increased number of HGVs in particular are anticipated. This paper describes the use of a simulation model OSCA (Overtaking on Single Carriageway - Assessment) to evaluate the effects of overtaking section length and type, traffic directional split and the provision of crawler lanes on traffic operation on single carriageway roads. The relationship between journey speed and flow is also considered. OSCA is a time scanning microscopic simulation model which allows the user to vary the geometry of the road section, road markings, the introduction of auxiliary markings , the introduction of auxiliary lane subsections, sight distances, traffic flow and composition, vehicle performance capabilities and desired speeds.
Abstract