This paper introduces an outline of a simulation model recently developed in Japan, for determination of the necessity of added lanes on existing two-lane rural roads. This model aims at utilisation of the existing road and traffic data for planning and design of added lanes for improvement of two-lane rural roads. The added lanes discussed in this paper are classified into two types according to the types of traffic operation, i.e. slower traffic lanes and overtaking lanes. The model consists of two sub-models; the road sub-model which represents road and environmental conditions and the traffic sub-model which reproduces existing and simulated traffic flow and behaviour. Formerly, the added lanes were constructed on existing national highways, based on traffic survey on volume vehicle behaviours, for which after-surveys were also conducted. The model was developed on these field surveys. The validity of the model was tested against actual field data, and in general the simulation results were concordant with them. The model developed in this study has made it possible to reproduce, with a pretty high accuracy, traffic behaviour on two-lane roads in rural areas. It also has successfully drawn up guidelines for installation of added lanes (A).
Abstract