New Method to Design Traffic Control Programs

Abstract

A control structure shows the sequence of realization of all green phases. Often, control structures designed for fixed-time control are based only on the order of the critical conflict group. When applied to vehicle-actuated control, structures based only on the critical conflict group regularly lead to inefficient control structures. Because of its flexibility, vehicle-actuated control requires a different approach for designing control structures. This paper presents a design method based on combining maximum conflict groups (mutual conflicting streams), resulting in all possible control schemes. Based on volume and saturation flow rate and assuming a uniform arrival process, each control scheme has a specific minimum cycle length. By ordering a control scheme according to its minimum cycle length and its flexibility to adjust green periods to varying traffic demand, the designer is supported in the process of choosing the most appropriate control scheme. This method was recently implemented in the Traffic Control Program Generator design support program and is used for training practitioners. If the minimum cycle length is less than the accepted maximum cycle, volumes can be increased proportionally to find maximum extension green times. In the near future, the Dutch province of South Holland intends to implement this method in a controller to generate online the most suitable control structure and control parameters.