下面这段英文的中心思想应该是什么?

下面这段英文的中心思想应该是什么?The traffic lights are the same in every country.There are always three lights:red,yellow and green.Red means “Stop”.Yellow means “Wait”,and green means “Go”.In China,drivers drive on the right side of the road.In the US,drivers drive on the right side,too.In England and Australia,however,drivers drive on the left side of the road.If you go by car,by bike or on foot,you must know the traffic rules.