Big, the biggest cause of accidents is a lack of concentration, I was smoking years ago & all the things you have listed, most people drive with never thinking "WHAT IF" a child is going to walk out from the front of that car etc, it beats me about Motorway accidents! how the hell should an accident happen when the traffic is on one side of a motorway & going one way, no roundabouts, right turns & in some cases no traffic lights.