A method of optimizing signal timing by the use of a linear programming technique is described. The linear program is based on the premise that the green time given to each traffic movement in the signal cycle must be long enough to handle the traffic coming into the intersection in one cycle. The linear programming method gives minimum signal phase times, minimum cycle time, and critical movements. The optimum signal phase times and cycle time can also be obtained in a nondirect manner. The linear programming method may be used as an off-line tool to analyze signal timing or it may be adopted as the basis for developing a new local controller for critical intersections of centrally controlled systems. When used as an off-line tool, the linear programming method is very effective for" what if" analysis of traffic signal timing problems.