UNIFIED TRAFFIC FLOW THEORY MODEL FOR TWO LANE RURAL HIGHWAYS

This paper presents the unified traffic flow model, a new approach to the problem of determining the level of service of rural two-lane highways. This method bases level of service primarily on speed and the ability to pass slower moving vehicles, which is dependent on the demand for passing in the main stream where sufficient passing sight distance is permitted by road geometry. Described briefly is how the model may be used for evaluating existing two-lane roadways and the depicting of numerous design solutions that can be considered. The range of solutions which can be evaluated includes auxiliary lanes such as climbing lanes and passing lanes and increases in the percentage of adequate passing sight distance. For the covering abstract of the conference see IRRD 286189. (TRRL)