the emphasis in traffic engineering has been changing over recent years from vehicles to people. this has shown itself in the development of pedestrianised areas and in priority measures being given to buses; these are now accepted parts of many traffic management schemes. the laboratory has been studying bus priority schemes, in particular bus lanes, in three ways: (1) controlled test- track experiments (2) theoretical simulations (3) studies of actual bus lanes. this paper describes a controlled experiment carried out on the laboratory's test-track,and gives some results showing how the saturation flow of cars and the time savings to buses are affected by the position of the end of the bus lane relative to the stop-line. some information is given on the effect of changing the position of bus bays. this experimental work is extended by means of a theoretical simulation of a bus lane, where different degrees of traffic saturation, together with changes in other variables, are dealt with. some results of this simulation are given which are compared with the results of the track experiment. the paper goes on to describe a simple theoretical model of an urban area which contains a comprehensive bus-lane network. the whole area, assumed to be homogeneous, is represented by a single link-the average main road. the position of the end of the bus lane is varied, which affects the capacity available for non-bus traffic. as the capacity varies, the amount of car, bus, taxi and goods vehicle traffic varies according to a 'demand' law assumed in the model. the effect of the bus lane on the total costs of travel can be seen and an optimum is found. the results show how the overall costs depend on whether the bus lane operates for peak periods only or all day. finally, the paper presents the summarised results of ten actual bus-lane schemes, giving figures for savings in delay to buses, savings or losses to other traffic and comments on particular aspects of the schemes which were relevant to their success or otherwise. (a)

Want to know more about this project?