Gap acceptance and traffic conflict simulation as a measure of risk

A new method of measuring gap acceptance behaviour of drivers is described. It has been used to study the behaviour of turning drivers at a selection of priority controlled T-junctions outside urban areas. The data thus obtained are used in a simulation model to predict conflict rates in turning manoevres. It is found that the ranking by frequency of conflict of such junctions given by this model agrees well with that obtained from five-year recorded injury accident data. The effect of various parameters, including age and sex of driver on gap-acceptance behaviour is discussed. A new model of headway distributions on major roads is given. (A)