One disadvantage of most conventional vehicle detection methods in a traffic control system is that they can only detect the vehicle in a fixed position. This paper proposed a new vehicle detection method using the wireless sensor network (WSN) technology. The striking feature of the proposed WSN-based method is that it can monitor the vehicles dynamically. This paper also developed a new signal control algorithm to control the state of the signal light in a road intersection. Simulations of the real-life intersection traffic control system are conducted in the paper. The simulation results show that the proposed method is effective for the traffic control in a real road intersection.