Apparently one lone motorist slamming on the brakes can cause mile-long tailbacks. That’s the conclusion we had come to following a string of inexplicable hold ups on various motorways in various years. (For what it is worth, I think this is bad marketing of science – no one has solved anything. Firstly there wasn’t a problem and secondly, no-one has done the experimental work to see if theory and practice agree.)
Is that what they called phantom traffic jams?