Project Overview
As one of America’s busiest hubs, Phoenix Sky Harbor International Airport in Arizona has serviced an increasing number of passengers every year since 2020. In 2024, more than 52 million passengers moved through Sky Harbor. Interstate 10, which runs adjacent to the airport, also supports a large number of travelers—in 2020, the Arizona Department of Transportation (ADOT) reported that I-10’s “Inner Loop,” which in part runs along Sky Harbor, was one of the most heavily traveled freeways in the region, carrying up to 300,000 vehicles per day. This, combined with the presence of more than 5000 businesses along an 11-mile stretch of I-10 near the airport, makes the region one of Arizona’s key commerce corridors. To address critical transportation challenges in the area—including severe traffic congestion, complex interchange navigation, and limited connectivity for pedestrians—ADOT engaged in the I-10 Broadway Curve Improvement Project, an endeavor powered by precast concrete products and spearheaded by precast concrete manufacturer Tpac and engineering firm Aztec Engineering.
Massive Project, Massive Results
Precast concrete bridges were an integral part of the project, with girders installed on 18 of the 21 bridges constructed. This included girders used for the rapid, 48-hour replacement of two bridges along the route. Bridge lengths varied significantly, from 1080 ft to just 39 ft. Overall, the project was a massive undertaking—bridges built with precast concrete comprised 55 spans hosting 68 lanes of traffic, totaling 6400 ft in length and 1050 ft in width. Some of the 306 girders manufactured included the largest prestressed girders produced in Arizona, measuring approximately 180 ft long and weighing more than 187,000 lb. According to Mark Chase, chief operating officer for Aztec Engineering, precast concrete was the material of choice on the project for a variety of reasons.
“Precast, prestressed concrete was chosen to eliminate the need for falsework over traffic, to expedite critical-path bridge construction by allowing superstructure work to proceed in parallel with the foundation construction, and to provide a cost-competitive means to accommodate the span ranges required by the project,” he says.
Chase adds that, beyond its scale, one of the project’s greatest challenges was the requirement to maintain all lanes of traffic in both directions at all times, except during designated closure periods at night and on weekends. Meeting this requirement using conventional falsework was feasible, but would have added significant cost and schedule implications to the work.
“The structural depth of the falsework would have raised the resulting profile of the system ramp bridges, creating downstream impacts to cost and schedule from taller and longer retaining walls and other major impacts to crossing overhead utilities,” Chase says. “Precast, prestressed concrete girders eliminated the need for restrictive falsework openings and provided the construction team with flexibility to keep the required lanes open using the entire pavement width available under the structures.”
Precast concrete’s ability to address the monumental traffic challenges generated was key to the I-10 Broadway Curve Improvement Project’s success. Specifically, the material’s superior strength allowed span designs that eliminated the need to split mainline traffic during construction. With six construction zones and just one area closure per weekend, precast concrete enabled the fastest possible installation within the project’s designated five-hour work windows. The result is a vastly improved roadway ecosystem located in the heart of one of Arizona’s most heavily traveled sectors and perfectly positioned for future performance.
“The completion of this project represents the culmination of many years of planning to improve this critical connection within the Valley’s freeway system,” Chase says. “The work has transformed the area into something that works for the benefit of daily travelers rather than a segment of freeway that, at times, became an impediment to daily travelers, given its high congestion and challenging configurations.”
Mason Nichols is a Grand Rapids, Mich.-based writer and editor who has covered the precast concrete industry since 2013. |