The main rule of traffic lights in the UK is that you must stop at a red light if the intersection or crossing is clear. You are not allowed to block the intersection or crossing. Cars turning left from the main road onto an adjacent road at a red light must wait for the green light before turning across the path of oncoming traffic. Turning cars coming from an adjoining road into a petrol station have priority over vehicles already on the forecourt when approaching a red traffic light. If there is no other traffic, then all drivers proceeding after stopping at a red, amber or green traffic light should use care when approaching intersections and drive slowly around them.