hir wrote:No, it's nothing more than a simple message to Mr & Mrs Joe public urging them... "not to drive too close to the car in front when you're driving on the motorway at 70mph!" And, yes, they paint some chevrons on the road but that's just to give the drivers some sense of spatial awareness and distance between themselves and the vehicle in front. It's not intended that the "rule" should have a specific, or logical meaning or interpretation. Mr & Mrs Joe Public wouldn't be able to cope with that at 70mph.
No. Someone intended to make it easy for Mr & Mrs Joe to see what sort of following distance would be good at motorway speeds. And they failed. Dismally.