This ensures excellent straight - line stability and, therefore, a high degree of assuredness when
travelling at motorway speeds and makes the SL very agile.
For instance, the computer model produced both the «shock waves» of congestion that
travel backwards down
motorways and create traffic jams where there is no obvious obstruction («When shock waves hit traffic», New Scientist, 25 June 1994), and the «slow fast - lane» effect, in which so many drivers move into the overtaking lane in frustration
at the middle lane's lower
speed that the middle lane becomes the fastest - moving.