How is this supposed to work?

Poorly!

Bravo! *Applause* The best answer. I mean, really: they should just ditch the arrows and have it a free for all. It hardly makes sense from an overhead perspective, I can't see it improving much from the ground level.

The arrows just make things worse.

Here's the Reddit discussion.

They say this is the Magic Roundabout in Swindon.

"In 2009 it was voted the fourth scariest junction in Britain, in a poll by Britannia Rescue."

This was number one: http://en.wikipedia.org/wiki/Spaghetti_Junction

Here is an animation of how the Magic Roundabout works:

On the other hand, it does not look nearly so bad if you look at it flipped:

1: Thanks!

2: Magic? That's . . . a funny name.

3: The red car flinched

4: Are the cars supposed to drive over the thick white lines?

5: I just noticed the squiggly lines/arrows. WHAT?

4 is a good question. As is 5. What?!