A new comprehensive sheared delay formula for traffic signal optimisation

This paper presents an alternative approach to the problem of optimising fixed-time traffic signal settings at an isolated junction for a single time period, where the degree of saturation for each traffic stream can be greater than one or less than one. A new comprehensive sheared delay formula has been developed based on the idea of coordinate transformation, which leads to an objective function that is differentiable throughout the range of feasible timings and can be used to calculate the derivatives of the objective function. Its acceptability and convexity are discussed and its application is illustrated by employing a stage-based approach to optimise the traffic singal settings for some example junctions.