The cost of a SPUI is very high due to the length of the bridge required. And signals have a way of being ignored.
Roundabout Corridors:
Arizona:
Sedona http://www.scenic179.com/Highways/Projects/SR179/ProjectMap.asp
Route 89A, Clarkdale (5)
Colorado:
Avon http://www.avon.org/index.aspx?nid=133
S Golden Rd in Golden (5)
California, Bird Rock http://www.slideshare.net/thecityalliance/bird-rock-ca-corridor-with-roundabouts
Florida:
Honore Ave, Fruitville to Bee Ridge, Sarasota (3?)
Indiana:
Most City intersections, Carmel
Kansas:
W 95th/Prairie Star Parkway, Lenexa (8)
Minnesota:
Shiloh Road, Billings (8)
Oregon:
SW Reed Market Road, Bend (5)
Sheldon Park/Newport Ave, Bend (5)
Washington:
State Rte 539, Bellingham, WA (4)
Grandview Dr, Olympic to 64th, University Place, WA (6)