设交叉路口的交通情况：有两条通行道路，分别沿方向1和方向2通行。每一方向都有红、绿、黄组成的交通信号灯。这些信号灯由相应的高有效信号（R1,G1,Y1,R2,G2,Y2）来驱动。此外，每个方向上都装有一个传感器，当相应方向有车辆要求通行时，传感器给出高电平有效的信号。-The set intersection traffic situation: two access roads, respectively, along the direction 1 and direction 2 pass. Each direction has a red, green and yellow traffic lights. These lights are driven by the corresponding active-high signal (R1, G1, Y1, R2, G2, Y2). Furthermore, in each direction are equipped with a sensor a vehicle request accessible when the sensor active high signal is given, when the corresponding direction.