It seems that fog is a 'blind spot' to perhaps most drivers. Last night we drove for miles in thick fog, from London along the A303. Basically there was no allowance being made by a majority of drivers who were simply driving on hope. On the radio traffic report within an hour there was an announcement that the A303 was blocked. Perhaps we could all drive one day a year with the inside of the windscreen coated with an opaque film, then we might see the point. Driving as we do in fog is probably more dangerous than drink-driving only more difficult to prove.