3-way junction traffic congestion is a severe problem in many modern cities all over the world. To solve the problem, we have designed a framework for a dynamic and automatic traffic light control system. The model adopts average arrival time and departure times, which are physically observed at each intersection of road to simulate the arrival and leaving number of cars during the run time period. In our experiment, by controlling light duration and speed limit, to avoid the accident by this system, the traffic congestion in a large city can be solved.