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Arizona DOT Increases Capacity on I-10 to Meet Rapid Population Growth

by: Larry Bernstein
Bridge work takes place on Miller Road as part of the I-10 Improvements Project in Buckeye, Arizona.
Bridge work takes place on Miller Road as part of the I-10 Improvements Project in Buckeye, Arizona.
Arizona is one of the fastest-growing states in the United States. Infrastructure needs to keep up with population growth or traffic will be slowed. The Arizona Department of Transportation (ADOT) is working on the I-10: SR85 to Verrado Way Improvements project to ensure sufficient capacity for motorists in the city of Buckeye.

Buckeye is approximately 25 miles west of downtown Phoenix, which is in south central Arizona. The project is taking place along an 8-mile stretch of I-10. In 2021, a traffic study recorded the average daily traffic count at I-10 and Verrado Way (the eastern end of the project) at 93,000 vehicle trips (counting both directions of travel) on average. The projection for 2040 is 128,000 trips per day.

ADOT has worked on multiple projects in the area over the years to accommodate the growing population. “Over the past 20 years, we’ve taken I-10, which we refer to as a key commerce corridor, from a four-lane rural highway and transformed it into a modern, urban freeway in the West Valley here in the Phoenix area. This project is another big advancement in preparing the area for additional growth in the coming decades,” says ADOT’s Central District Administrator Randy Everett.

The scope of the current project includes widening I-10 by one lane in each direction along the entire project length. The expansion to three lanes each way is sorely needed as I-10 handles a tremendous amount of commercial vehicle freight between Los Angeles and Phoenix.

“Buckeye is one of the fastest growing cities in the West, and the wider freeway and interchange improvements will make a significant difference for local drivers and businesses, our state’s overall economy and the movement of western U.S. commerce,” Everett says.

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At the western end of the project is SR 85. The route is a primary north-south connection between I-10 and I-8 west of the Valley of the Sun (Phoenix metroplex) and carries a great deal of Arizona’s traffic traveling to and from the San Diego area. As part of the project, crews are widening the freeway-to-freeway ramps connecting I-10 with SR 85 to allow those connections to fit with the interstate’s wider configuration.

Bring in the Diamonds
The project includes a few other significant elements. The team is reconstructing traffic interchanges at two roads that I-10 crosses along the 8 miles. The new interchanges will be converted to the Diverging Diamond Interchange design (DDI). ADOT decided on DDIs because these interchanges tend to reduce the number and severity of crashes, while reducing traffic congestion.

Other benefits of DDIs include being cost-effective to build and causing fewer impacts on the local community during construction. Finally, they integrate well with multimodal facilities for pedestrians, cyclists, and transit.

The team is also constructing new drainage facilities, including storm drains and catch basins. Sound walls are being constructed along I-10 as needed. A freeway management system (FMS) – including digital message boards, closed-circuit freeway cameras and traffic-flow detectors in the pavement – is also being installed. ADOT's growing network of FMS technology throughout the state allows the agency to better track traffic conditions and provide updated information to drivers.

Part of a Community
Buckeye’s population is just over 100,000. Doing construction in a crowded area requires planning to minimize the inconvenience for travelers and pedestrians alike.

“One of our top challenges has been easing the impacts on the local community, its businesses and residents. Anytime you need to close on- or off-ramps down for weeks at a time for reconstruction work, you have to provide adequate detour routes and communicate with the city and drivers on a regular basis, which we’ve done,” says ADOT Resident Engineer Cliff Oltman.

The team has adjusted the schedule in response to this challenge. “We’re delivering this project as the latest in a series of steps to manage the flow of traffic, including the great deal of commercial freight traffic on I-10, as this area grows to the west from Phoenix,” Everett says.

Adjusting the schedule to meet multiple requirements necessitates good communication. “We’ve met the challenges …with pre-planning while developing and understanding multiple concepts as you arrange the phasing of the construction,” says FNF Senior Project Manager Mike Caruso. FNF is serving as the general contractor. The Arizona-based firm specializes in heavy highway and general construction. “We've had open communication and coordination meetings with all key team members that have been essential.”

Caruso also notes that the existing volume of traffic and limits on lane restrictions created challenging work hours related to critical path construction activities.

Another wrinkle in project scheduling was Super Bowl LVII, which took place on February 12, in nearby Glendale, Arizona. Oltman says, “We had extensive discussions with Buckeye’s team, since the city had its share of visitors using local hotels as the big game approached. We arranged a schedule to reopen the eastbound I-10 off- and on-ramps at Watson Road, which were undergoing reconstruction, with time to spare ahead of Super Bowl weekend.”

State Funded
The project began in July 2021 and is scheduled to be complete on time this summer.

The $82 million project is being funded by the Maricopa Association of Governments (MAG), which serves as the metropolitan planning organization for the Phoenix area. They've overseen the planning of urban freeway expansion and worked with ADOT on scheduling and delivering projects, including the I-10 widening in Buckeye.

“The funding for this project comes from MAG’s Regional Transportation Plan, which includes the region’s share of federal highway dollars and a regional half-cent sales tax approved by Maricopa County voters in 2004,” says ADOT spokesman Doug Nintzel.

Upon completion of the project, area drivers and commercial vehicles that travel I-10 will enjoy reliability along the route. The DDIs will improve safety. Finally, the expanded highway will accommodate the future growth that's anticipated to arrive in the area.

Photos courtesy of the Arizona Department of Transportation

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