Δαφνη Ευτυχια Αρθουρος

There was a Scientific American article a number of years ago (wish I had kept a copy) about density waves traveling through traffic. Above a certain traffic density, a slight slowdown can cause traffic to come to a halt some distance back. This is basically the fallacy of "rubbernecking" that you hear about on traffic reports all the time. As amusing as it is to believe that big traffic jams on the opposite side of the road from an accident are caused by idiots slowing down to 5mph to "take a look," they're actually caused by people slowing down a little bit when they see a problem ahead, but don't yet know if it affects them. (This is why there aren't rubbernecking delays when traffic is light.) Does anyone believe we'd be safer if people didn't slow down when they see trouble ahead?

Another interesting bit from the article is that density waves travel backward and forward from an incident. I've recognized this once I learned to look for it; people think they're out of the woods and try to speed up to cruising speed, but things haven't quite cleared out enough, so it jams up again. It can be pretty mysterious if you get onto the road after the incident, though; you keep hitting slowdowns, but never pass anything that has caused them.