MANTECA (CBS SF/Sacramento) — The first-ever “diverging diamond” highway interchange in California is set to open Thanksgiving Week in Manteca three months early.

Crews are putting the finishing touches on the project, which is located on Union Road over Highway 120. A diverging diamond interchange has been talked about for decades in Manteca and officially went under construction in June 2019.

The highway design got its name because it looks like a diamond from overhead. It works like a roundabout — shifting traffic to the left side of the road, before being shifted back to the right — eliminating left-hand turns through the intersection.


More Californians are looking to the Central Valley for housing and, for Manteca, that means new traffic loads. That’s the motive behind the new interchange at Highway 120 and Union Road.

It will also be a new driving experience for those who have never passed through one in another state.

”I don’t think motorists are ever really confused by it, except when they try to understand it,” said Bart Ney, Bay Area Caltrans chief of public affairs. “When they drive it it’s very natural and it’s actually easier.”

The new interchange also offers a separate pedestrian and bike path.


CBS SACRAMENTO: California’s First Diverging Diamond Interchange To Wrap Construction In Manteca

CBS SF: Diverging Diamond Interchanges Coming to California to Ease Traffic Congestion