Superstreets

No left turns means more efficiency. [Link]

Superstreet intersections are designed for situations where you've got a major road intersected by a bunch of smaller roads. What generally happens in these situations is that the people on the smaller roads trying to get across the major road have to wait forever, or if there's a traffic light, all of the traffic on the main road has to stop and wait for just a couple cars to get across. This is horribly inefficient, not to mention frustrating.

The Superstreet intersection attempts to solve this problem by entirely doing away with left turns and preventing streams of traffic from directly crossing each other. To cross a Superstreet, traffic from side roads must first turn right, joining the main flow of cars. A dedicated u-turn lane allows you reverse your direction, at which point you can continue straight (effectively making a roundabout left turn), or turn right, which gets you across the intersection.