Progress continues on new Happy Valley Road bridge over I-17

By Foothills Focus Staff

The new bridge that will be part of the first full diverging diamond interchange along an Arizona freeway continues to take shape at Interstate 17 and Happy Valley Road in North Phoenix.

Crews have poured the concrete deck for the second half of the new bridge the Arizona Department of Transportation is building to carry Happy Valley Road traffic over I-17.

The work is part of a $50 million ADOT project to reconstruct the I-17 interchanges at Happy Valley and Pinnacle Peak roads. Construction began in November 2018 and is scheduled for completion in the fall.

The first half of the Happy Valley Road bridge was opened to traffic earlier this year. That allowed crews to tear down the old bridge and continue work on the second half of a larger structure over I-17.

The updated I-17 interchange at Happy Valley Road is being constructed with a diverging diamond design, which has grown in use across the country. The interchange will allow Happy Valley Road traffic approaching the bridge over I-17 to cross to the opposite side of the structure so drivers can make direct left turns onto a freeway on-ramp. The design promotes safety by reducing conflict points for opposing directions of travel and enhances traffic flow by limiting traffic signal sequencing.

ADOT also has constructed two smaller “half” diverging diamond interchanges on the new South Mountain Freeway along two roads that do not extend south of Loop 202.

Meanwhile, reconstruction of the I-17 interchange at Pinnacle Peak Road also is moving forward. That interchange will operate as an expanded traditional diamond interchange featuring additional lanes to handle growing traffic along Pinnacle Peak Road.

The project also is adding one lane in each direction along I-17 in the area between the Pinnacle Peak and Happy Valley interchanges.

The I-17 interchange reconstruction project at Happy Valley and Pinnacle Peak roads is part of the Maricopa Association of Governments’ Regional Transportation Plan for the Maricopa County region. A primary source of funding is a half-cent sales tax for transportation improvements approved by county voters in 2004.

With state highways essential to delivering goods and services, ADOT, its employees and its contractor partners are dedicated to delivering transportation improvement projects during the current public health situation. To learn more, visit