The state’s first major Diverging Diamond traffic interchange at Interstate 17 and Happy Valley Road, some 25 minutes north of Glendale, is scheduled to open to traffic on Sunday, Oct. 11, according to the Arizona Department of Transportation.

The majority of the reconstructed interchange will open in a temporary configuration as part of a phased plan. Some lane restrictions will be in place on Happy Valley Road and the I-17 exit ramps until all work is completed later this fall. Drivers can look forward to using a modernized interchange with more lanes on the new bridge crossing over the freeway.

The Diverging Diamond interchange design includes intersections and traffic signals that will allow drivers to cross to the left side of the Happy Valley Road bridge over I-17. That switch means motorists can make direct turns onto the freeway entrance ramps rather than waiting to turn in front of traffic traveling in the opposite direction.

A reduction in such conflict points and fewer traffic-signal sequences are safety enhancements that also allow an improved movement of vehicles through the Diverging Diamond interchange.

All I-17 on- and off-ramps at Happy Valley Road will be closed from 9 p.m. Friday to 5 p.m. Sunday. Happy Valley Road also will be closed in both directions approaching I-17.

ADOT is nearing completion on a $50 million project to reconstruct the I-17 interchanges at Happy Valley Road and Pinnacle Peak Road. The section of I-17 between Happy Valley and Pinnacle Peak roads also has been widened by one lane in each direction. Work on the project started in November 2018.

ADOT’s project was funded as part of the Regional Transportation Plan approved by Maricopa County voters in 2004.