TBH, if you are going to have smart intersections controlling autonomous cars, you might as well try to move to roundabouts as much as possible.

Roundabouts provide continuous flow and probably represent a much more solvable problem since it involves attenuating the speed of approaching vehicles and vehicles currently circling. I imagine throwing stopping into the mix complicates things significantly

I imagine that computers could completely prevent shockwave traffic jams. http://www.youtube.com/watch?v=Suugn-p5C1M

I suspect roundabouts are also more expensive and take up more space than traditional cross intersections.

Surprisingly, I've often heard the following argument (except your point about space). Traditional intersections, despite being cheaper to install, are less economical from a total cost of ownership and all associated externalities perspective

The other benefit of roundabouts is they provide a much simpler situation for cars to encounter, since the intersection could be dumb and simpler heuristics should be able to resolve the management of traffic. A simple four way stop sign wouldn't be too hard, but I can't imagine trying to figure out much less optimize a complex highly trafficked 4 way intersection. A 4 way intersection basically forces you to coordinate centrally to optimize, instead of distributing the logic among participants in the intersection and only putting in central coordinating logic when traffic is very heavy. And even then, I'd expect it more to provide information to the vehicles entering about the vehicles already present and about to enter and letting the vehicles decide what is best.

I was going to write a big screed about how adding traffic lights and all the associated equipment would be much more expensive, then I realised you were talking about stop signs!

Intersections don't really have to be much bigger, and at minimum all you need is a circle painted in the middle of the intersection. Roundabouts work well when traffic flows in all directions evenly, but if not it's pretty easy to get into a situation where cars entering from a particular direction get screwed when there's lots of traffic.

I've always thought that "smart intersections" were an obvious step to be made when we have self-driving cars. It's nice to see work is being done on this front.

I would be interested to see if the intersections we already have could be made a bit smarter, especially when the roads aren't so busy. If computer vision was used to tell that cars were coming, then the lights could be smart enough to change when needed, and the lights shouldn't need to rigidly cycle through everything to let that one car go through.

When you are making the lights anticipate the every move of cars, please make them anticipate the every move of pedestrians too.

http://www.youtube.com/watch?v=r7_lwq3BfkY vs http://www.youtube.com/watch?v=cVo4XHXZp1c

Self-driving cars need to have their windows blacked out.