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Double Roundabout Interchange

Design and Operations

The Double Roundabout interchange uses Roundabouts instead of signal- or stop-control at Diamond interchange ramp terminals. Intended benefits include reduced delay for ramp traffic, a narrower bridge width, and the elimination of signal coordination and progression issues between the two ramp terminals.

The Roundabouts in the Double Roundabout design can have two different shapes, either circular or "raindrop". The use of true circular islands is desirable when U-turns or access to other approach legs are to be permitted. Raindrop-shaped central islands eliminate direct U-turn movements (U-turns can be made by circulating around both Roundabouts), but reduce yielding conflicts for vehicles entering the Roundabout from the ramps, thus improving the capacity of the Roundabouts and reducing ramp delays and queuing.

Update date: 05/21/2013 by Song
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