设有一十字路口，1、3为南北方向，2、4为东西方向。每个路口均有红、黄、绿三个灯，初始状态为四个路口的红灯亮，2秒之后，1、3路口的绿灯亮，2、4路口的红灯亮，1、3路口通车；延时50秒后，1、3路口绿灯闪烁5秒后绿灯灭，黄灯亮，5秒后，1、3路口的红灯亮，而同时2、4路口的绿灯亮，2、4路口开始通车；延时30秒后，2、4路口绿灯闪烁5秒后绿灯灭，黄灯亮，5秒后，2、4路口的红灯亮，同时1、3路口的红灯亮（即四个路口的红灯亮），2秒之后，1、3路口的绿灯亮，2、4路口的红灯亮，重复上面的过程。-There is a crossroads for the north-south direction of 1,3, 2,4 for the east-west direction. Each intersection are red, yellow and green three lights, the initial state for the four junctions of the red light, 2 seconds after the green phase at the junction of 1,3, 2,4 at the junction of the red light, 1,3 junction opened to traffic　 delay after 50 seconds, 1,3 junctions five seconds after the green light flashes a green light out, bright yellow, 5 seconds later, the red light at the junction of 1,3, while the green at the junction of 2,4, 2,4 junction opened to traffic　 delay 30 seconds later, 2,4 junctions five seconds after the green light flashes a green light out, bright yellow, 5 seconds later, the red light at the junction of 2,4, 1,3 at the same time the red light at the junction (that is, the red light at the junction of four ), 2 seconds after the green phase at the junction of 1,3, 2,4 at the junction of the red light, repeat the above process.