假设一个十字路口为东西南北走向。开始为四个路口的红灯全部亮之后,东西路口的绿灯亮,南北路口的红灯亮,东西路口方向通车,延时一段时间后（20秒）,东西路口的绿灯,闪烁若干次后（3秒），东西路口的绿灯熄灭，同时东西路口的黄灯亮,延时一段时间后（2秒）,东西路口的红灯亮,南北路口的绿灯亮,南北路口方向通车,延时一段时间后（20秒）,南北路口的绿灯闪烁若干次后（3秒）,南北路口的绿灯熄灭，同时南北路口的黄灯亮，延时一段时间后（2秒）,再切换到东西路口的绿灯亮,南北路口的红灯亮,之后重复以上过程。-Assuming a crossroads of East and West direction. Start all four red light intersection after crossing things green light red light intersection north and south, east-west direction crossing traffic, the delay period of time (20 seconds), something intersection green light flashes several times after ( 3 seconds), the green light goes something intersection while crossing the yellow light thing, the delay period of time (2 seconds), something intersection red light, green light junctions north and south, north-south crossing direction to traffic, after a period of delay (20 seconds), north-south crossing the green light flashes several times and (3 seconds), north-south crossing the green light is off, while the yellow light north-south junction, the delay period of time (2 seconds), and then switch to something green light junction, North-South junction red light, then repeat the process.