Anatomy of motorway congestion

I have a one hour drive to and from work every day. Because of this I start to notice certain patterns I didn't see before.

For example, motorway congestion almost always follows the same pattern.

1. Traffic in the fast lane slows down so that there is little difference between the fast and the middle lane
2. Quite suddenly, the traffic slows down dramatically. This almost always affects the fast lane first, then the middle lane, then the slow lane. This is because the slowing of the traffic is like a wave which is transmitted backwards along the route and faster traffic transmits it faster.
3. At this point it is best to head into the middle or or slow lane. Most people don't realise this and pile into the fast lane in frustration, slowing it down more.
4. As the worst of the congestion passes, the pattern changes - the traffic in the fast lane starts to speed up first. At this point, it's best to get back into the fast lane.