Interstate 17 Flood Control Upgrades Coming Soon

By Scott Bourque
Published: Monday, September 2, 2019 - 9:21am

Interstate 17 flooding
Arizona Department of Transportation/Twitter
A photo from Indian School 17 and Indian School Road in Phoenix, where floodwater closed the highway in both directions during a storm.

During last week’s monsoon, several underpasses along Interstate 17 in north Phoenix flooded, causing traffic delays. This isn’t an uncommon occurrence: in September 2014, flooded underpasses shut down sections of U.S. 60, I-17, and portions of Interstate 10 for several hours — and, in some cases, several days — while outdated pumping stations worked to remove the water.

The Maricopa Association of Governments (MAG) and Arizona Department of Transportation will begin work on flood control upgrades to four underpasses along I-17 in the next few weeks. The project is expected to take up to two years to complete. 

According to MAG’s Transportation and Finance program manager John Bullen, the core of this work will involve replacing old pumping stations, which use large engines to remove floodwater.

“The pump stations aren’t as efficient as they once were,” Bullen said. “They’re old, which means they don’t quite work well.”

Instead, the underpasses at Peoria Avenue, Cactus Road, Thunderbird Road, and Greenway Road will be fitted with a gravity drainage system that will channel water to the Arizona Canal and a new drainage basin. 

“This gravity-fed system is anticipated to work significantly better and certainly reduce the potential for flooding,” Bullen said. 

This project is one of many planned for Valley freeways under MAG’s 2040 Regional Transportation Master Plan. 

Flooding on U.S. Route 60
Jackie Hai/KJZZ
Flooding on U.S. Route 60 after a monsoon storm in August 2017.

I-17: A key Corridor — And A Roadblock

In the regional transportation plan, Interstate 17 is slated for significant upgrades between now and 2040. MAG expects to spend close to $1.5 billion on upgrades to the I-17 and I-10 “Spine Corridor” over the next 21 years. 

Most of those upgrades won’t involve the freeway mainline itself, but instead will focus on the arterial roads crossing it. The interchanges are “pinch points” in the east-west transport system, according to multiple MAG studies.

“More traffic actually crosses I-17 than uses it,” Bullen said. “This project in particular will address a lot of those connectivity issues around the freeway and enable that east-west traffic.”

The interchanges at Happy Valley and Pinnacle Peak Road are currently under construction. Upgrades to Indian School Road interchange are currently in the planning phase, according to Bullen. 

The I-10/I-17 Master Plan calls for nearly every arterial road crossing the freeway to have interchanges upgraded between now and 2040. 

Proposition 400 Funding

Maricopa County voters approved funding for these projects when they voted for Proposition 400 in 2004. 

The proposition authorized the county to continue collecting a half-cent sales tax — originally authorized by voters in 1984 — through 2025. Revenues collected from the sales tax go into funds for highways, arterial roads, and public transit. 

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