>They cross because the car on the sign has spun 180˚ rather than simply sliding. As the car spins the tracks from the left wheels cross over the tracks from th

>They cross because the car on the sign has spun 180˚ rather than simply sliding. As the car spins the tracks from the left wheels cross over the tracks from the right. Which means that when UK roads are slippery, they are really slippery, or maybe continental drivers manage to get away without a 180° spin. However if we want to be picky, the traces of a 180° spin are different, there are generally two crossings, unless two wheels (on the same axle) loose contact with the road.