The roundabout on the Cambridge side of the BU bridge, which I unfortunately have to take home most evenings, is something I can't imagine a driverless car handling. Sometimes it's a single-lane roundabout, but at peak hours it can support as many as five cars wide, eventually merging into a single lane over the bridge, and the traffic pattern is different every day.

Driving on highways is easy, and solving that is still valuable, but it's going to be amazing to see these things work in situations like those.