An adaptive control system is developed using a fuzzy method to improve the traffic control system performance and to reduce the overall delay for four phases simple intersections within a grid of network. The main functions of the developed control system are to accelerate the cycle time and to reduce the loss time by determining the green time for each phase based on traffic flow. The fuzzy rules are employed using visual basic and computer-based program (Excel) to run the validation process. The developed control system is tested on five intersections in a simulated network in the State of Kuwait during four different peak periods. The results indicated that the number of vehicles passing through intersection phases has increased in most phases by an average of 12.9%, 23.3%, 10.4% and by 21.2%. The green time is increased by an average of 9.1%, 5.8%, 9.9% and 6.3%. Number of intersections' cycles remain constant at most of the time which means that the developed control system distributes the green phases' times based on the traffic situation. The developed control system can be applied on simple intersections with four perpendicular phases that consist of collector, major arterial or minor arterial roads.