You may have seen some of the articles in the press this year on the subject of Phantom Jams, which, unfortunately have nothing to do with ghost cars.
These are the traffic jams that appear, seemingly from nowhere, and gradually propagate backwards down the road. All of a sudden, these seem to have attracted the attention on mathematicians, who are publishing papers on the phenomenon at an alarming rate.
First Bristol University published the results of an investigation they had conducted on the M42 near Birmingham, utilising the huge numbers of cameras on that particular motorway (Yes, the ones that monitor and enforce the variable speed limits.) Their aim is to improve mathematical models of these jams, so that more accurate forecasts of journey times can be made.