Traffic Signal Controller for Mixed Traffic Conditions

Fuzzy logic has been widely used to develop an adaptive traffic signal controller because it allows qualitative modelling of complex systems. However, existing research has developed Fuzzy Logic Traffic Signal Controller (FLTSC) based on non-mixed traffic conditions. These FLTSC are not appropriate to the mixed traffic conditions of developing countries where the traffic streams consist of different types of vehicles with a wide variation in their static, dynamic and operating characteristics. This paper describes the design and evaluation of an adaptive traffic signal controller based on fuzzy logic for an isolated four-way intersection with specific reference to mixed traffic in developing countries. The controller is designed to be responsive to real-time traffic demands. Video image processing has been proposed to capture traffic data such as maximum queue length (in metres) and average occupancy rate (in %) from each approach of the intersection. The proposed FLTSC uses maximum queue lengths and average occupancy rates collected during the previous cycle in order to estimate the number of seconds of green time required by each set of signal groups (stage) during the next cycle. The effectiveness of the proposed FLTSC was examined and analysed by the simulation program VISSIM. The performance of this controller is to be contrasted with the Fixed Time Controller (FTC) and Vehicle Actuated Controller – Extension Principle (VAC-EP) for different traffic conditions on a simulated fourway intersection. The simulation results indicate that the performance of the proposed FLTSC is generally better than the FTC and VAC-EP, especially in cases time-varying traffic.