But that couldn't have happened if they'd been going at a constant speed, or if they'd changed their speed to even out the gaps when they formed.

So the real reason for traffic jams likes this is because people suck at driving. =S

Now I know...

Not exactly...
Not everyone is going the same speed. So when someone gets to close, they slow down, which causes a chain reaction and BAM, theres a traffic jam

There are a lot of wave dynamics principles used when studying and designing for traffic flows. This is a great example of that.

Now that I know, I'll probably still give innocent victims the bird if I feel they're slowing me down.

I agree with Mashirafen, people just suck @ driving...
Slamming on your brakes w/o reason causes jams...
Hm... maybe it's a good idea to try that in practice; just slam on your brakes when cruising along on the motorway! see what happens!

the problem with most drivers is they act like they're the only people with places to go. If im in a car, chances are im trying to get somewhere too...

Or people are just retarded

I do agree that it is so retarded when people go UNDER the speed limit. My dad does it sometimes, and to me it is inconsiderate. Just because you have some extra time to get somewhere, doesn't mean the person behind you doesn't have an extra 15 minutes to waste driving slowly. People plan their schedule around driving the speed limit to get somewhere. If they go under, often they are late.

Now if someone is going the speed limit and someone behind them will be late because they usually go 10 over the speed limit, that's a different story because they planned their schedule around breaking the law.

Amazing.