Not Just Big: Arizonas Loop 303, I-10 Five Stack
The largest highway interchange in Arizona—a five-tiered structure soaring more than 90 ft into the desert sky—is being constructed by Pulice Construction along the fringe of the Phoenix metropolitan area between Interstate 10 and the Loop 303.
But the height isn't the primary reason that the project is considered to be big. In fact, the height of the columns is comparable to most other five-tier traffic interchanges. It's the project's footprint, including frontage roads, that will make it the largest full-system interchange in the state, says Andrew Baird, project engineer with Phoenix-based Aztec Engineering.
The $139-million effort's massive footprint is nearly 1 sq mile. Within the footprint, work includes rerouting traffic at least three times over the course of the project along I-10—which has an average daily volume of more than 150,000 vehicles. Other challenges include redirecting and rebuilding a major irrigation canal, adding two flyovers for a future expansion of the interchange and managing the relationship with a nearby women's prison.
A LONG TIME COMING
The Loop 303, still under construction, is the newest and possibly last piece of the Phoenix metropolitan area's freeway system and has been designed to make traveling north-south through the western portion of the Valley of the Sun easier. Situated nearly 30 minutes west of downtown Phoenix, the interchange will carry traffic between the existing I-10 and the new Loop 303 starting in fall 2014.
Though it is sparsely populated today, planners and analysts expect the area near the freeway to experience large-scale growth. The Greater Phoenix Economic Council has predicted that over the next decade, 68% of the Phoenix metropolitan area's growth will come from the West Valley.
Ground was broken on the construction of the five-tier interchange in November 2011, and the project is approximately 65% complete as of June. Up to nine cranes have been used at one time to aid in the erection of the 16 major structures on the project, according to Juan Miranda, project manager for Pulice Construction of Phoenix. The general contractor has employed up to 250 workers at one time at the site.
Fourteen of the structures are cast-in-place, post-tensioned box girder bridges of various widths and lengths, according to Miranda. Four of the structures are freeway-to-freeway directional ramps, including the east-to-north and south-to-east connections and portions of the west-to-south and north-to-west flyover ramps.
At more than 3,400 ft, the longest bridge is the east-to-north route. It consists of six frame columns more than 94 ft tall. The two bridges at I-10 over Sarival Road at the eastern end of the project are type-V AASHTO precast girder bridges. Collectively, all the major structures include more than 16,700 linear ft of drilled shafts between 48 in. and 120 in. in diameter, more than 13.8 million lb of reinforcing steel and 71,200 cu yd of structural concrete.
The earthwork is also immense. Nearly 6.5 million cu yd of material will be moved over the life of the project, including 2.2 million cu yd used for roadway excavation and 1 million cu yd for soffit fills and falsework grading.