The munipal transportation signal control is through the adjustment，the waning and the induction which flows to the transporation achieved improves the person and the cargo safe transportation, enhancig the operation efficiency. Transport system is a random nature, ambiguity and uncertainty of complex systems, the establishment of mathematical models very difficult and sometimes impossble to use existing mathematical methods described. the most adaptive signal control is used,it needs mathematical model,without considering traffic delays,And vague control is a mathematical model to control methods, it can imitate experienced police directingtraffic,ideas, achieve good control results. In recent years many of our scholars have different ideas of individual junction, traffic control Route vague studied, but the limitations of the theory and research scholars, the few practical applications, based on this achievement traffic signals vague PLC control system.
According to determine signal distribution and flow of the control system vague theoretical resesrch results, the achievement of individual intersections with traffic lights blur PLC control methods for individual crossroads 4 phase of traffic lights, for example,the PLC as an ambiguous signal controllers using Ladder programming. through experiments that the reliable operation of the system to a vague under different traffic control decision-making, optimize signal distribution, which can effectively solve traffic imbalance,instability brought.
Keywords：Transportation; Intelligent control; PLC
