Changes coming to I-17 and Happy Valley Road and Pinnacle Peak Road

Interstate 17 Traffic Interchange Reconstruction – Happy Valley Road and Pinnacle Peak Road

Coming Soon - No more round-abouts at Happy Valley and Pinnacle Peak Rds! ADOT will be constructing Diverging Diamond Interchanges at both locations, check out the video in the link. Construction will start in the fall of 2018 and continue for apex. 20 months.

The Arizona Department of Transportation (ADOT) and the Federal Highway Administration (FHWA) have initiated a project to reconstruct the traffic interchanges on Interstate 17 at Happy Valley and Pinnacle Peak roads. The purpose of the project is to improve regional traffic flow as the population grows and development continues in this area of north Phoenix. 

Project Schedule

Design began in 2017 and scheduled for completion in summer 2018.

Construction is scheduled to begin in the fall of 2018 and last approximately 20 months.

Pinnacle Peak Road Traffic Interchange

The scope of work includes:

·         Constructing a new Tight Diamond traffic interchange

·         Constructing a new underpass bridge that would accommodate potential future expansion of I-17

·         Reconstructing Pinnacle Peak Road to two through lanes in each direction with right- and left-turn lanes as needed

·         Extending the existing culverts and re-grading the detention basins

·         Constructing retaining walls

·         Installing Freeway Management System signage, ramp meters, signals, lighting and pavement markers

·         Re-seeding areas disturbed by construction

Happy Valley Road Traffic Interchange

The scope of work includes:

·         Removing the existing roundabouts and constructing a new traffic interchange. A Diverging Diamond traffic interchange is planned for this location. 

·         Constructing a new underpass bridge that would accommodate potential future expansion of I-17

·         Reconstructing Happy Valley Road to three through lanes in each direction with right- and left-turn lanes as needed

·         Re-grading the detention basins

·         Installing Freeway Management System signage, ramp meters, signals, lighting and pavement markers

·         Re-seeding areas disturbed by construction

Construction at both interchange locations is anticipated to occur within existing ADOT right-of-way.

The Diverging Diamond Interchange (DDI)

A DDI is a diamond interchange on which the two directions of traffic on the cross street (above or below the freeway) cross to the opposite side on both sides of the bridge at the freeway. In the United States, more than 80 DDIs have been constructed in 29 states since 2009. The design has increased in popularity because of safety, operational and cost benefits. DDIs can reduce the number and severity of crashes compared to traditional diamond interchanges, while reducing traffic congestion. They also provide an excellent opportunity to integrate multimodal facilities for pedestrians, cyclists and transit into the interchange. They can be more cost effective to build, and there are fewer impacts on the local community during the construction process.

If you’re curious to see how a DDI works, watch this video from the Illinois Department of Transportation (IDOT). Recently IDOT constructed a DDI at I-88 and Route 59 near Chicago. This DDI’s design is similar to what is being planned for I-17 and Happy Valley Road.