Interstate 17 is a vital roadway for Arizonans and a major connector along the state highway system, linking I-10 and I-40. In addition to serving as a major interstate route to move people and goods between metro Phoenix and other parts of the country, I-17 also is the primary route to northern Arizona and the only highway serving the growing communities north of Maricopa County.
The Arizona Department of Transportation (ADOT) recognizes its importance as a vital roadway for regional, intrastate and interstate travel, as well as an emergency travel route between northern and central Arizona.
More than 27,000 vehicles travel on Interstate 17 at the junction of state Route 69, with predictions by ADOT that this volume of traffic will more than double by 2020. Built in the early 1960s about 65 mi. (105 km) north of Phoenix, the Cordes Junction traffic interchange at the intersection of I-17 and SR 69 serves 27,500 vehicles on an average day.
Cordes Junction is a residential area featuring gently rolling hills with panoramic mountain views. An easy commute to Phoenix, Prescott, Flagstaff and Sedona, it is a heavily traveled corridor.
The current interchange design mixes local and through traffic, causing frequent congestion and delays, according to Tricia Lewis, senior community relations officer of ADOT. Therefore, a plan to reconstruct it was put into place.
Long-Awaited Project
The project will create two separate interchanges — one for through traffic and a diamond for local traffic. It includes construction of seven bridges and numerous new ramps, as well as realigning, widening and paving several associated streets.
The project, which will be constructed in four phases, includes construction of a new traffic interchange approximately .5 mi. north of the existing interchange. The new interchange will provide access to the businesses at Cordes Junction, the Cordes Lakes community and Arcosanti.
The outdated on- and off- ramps have been removed and replaced with new ramps to carry Prescott-bound traffic over I-17. High speed Prescott-bound traffic is separated from Cordes Lakes travelers driving at slower speeds. The existing bridges carrying I-17 over Big Bug Creek also were replaced and a new interchange to the north will be constructed.
Two new roundabouts were constructed to improve safety and traffic flow. “Roundabouts work effectively in high-capacity intersections and have increased the capacity and movement through the region,” Lewis said.
Lewis said the roadways are designed to meet current standards. “The project included the construction of a modern interchange with the capacity to handle increased traffic in the area,” she said. “Because it uses an outdated intersection design, local and through traffic are forced to mix, causing congestion and safety concerns. The new interchange improves traffic flow and safety, while separating local and highway traffic.”
Scheduling
Funded by federal highway funds, the $50.9 million contract is a joint venture between Vastco Inc. and Sundt Construction Inc., which together become the project’s Construction Manager at Risk.
Work started in August 2011. With 12 to 25 workers on site daily during the final phases of the project, Lewis said the project is expected to be completed on time by the end of June 2013.
To win the job, Vastco-Sundt needed to demonstrate to ADOT how it intended to keep traffic flowing while the interchange was being rebuilt. The company believes the use of automated machine guidance has been critical for keeping the project on schedule and for providing accurate surveying.
The largest part of the project involved the construction of seven new bridges, three of which were built over “live” traffic on I-17. Therefore, construction sequencing was critical, and because the project schedule was very aggressive, there was little room for error.
Using dozers, scrapers, loaders, backhoes and haul trucks, crews have maintained a “typical work schedule during the evenings [of] Sunday through Thursday and during the day, Monday through Friday with some weekend work,” said Lewis.
That schedule has been difficult, she said. “The largest challenge has been the restriction of only being able to do work on I-17 during the Sunday to Thursday nights.” However, she added, through the “partnering process,” ADOT and the contractor were able to accomplish the work under these restrictions.
“Anytime you have a project of this magnitude, there are a lot of challenges and a lot of moving parts,” Lewis continued. “Fortunately, with great cooperation from our contractors, this project is scheduled to be completed on time. One of greatest challenges has been traffic-related, since Interstate 17 is a heavily traveled corridor. That’s why ADOT has scheduled most of the major work that required closures during overnight hours when traffic volumes were at their lowest.”
Phased in
The project was designed in four phases to minimize the impact to the local community and the traveling public and maximize cost-effective procedures. “This project includes eight bridges, two roundabouts, a flyover bridge and three new [or improved] local roads,” Lewis said. “Due to the magnitude of the project, phases were required to allow for live traffic to continue to use the Interstate and access the local area.”
Phase 1 (August 2011 to October 2011) did not required any closures. However, night time lane restrictions allowed crews to conduct shoulder work and temporary detours on SR 69 and median crossovers on I-17 enabled construction crews to widen sections of both roads and to safely build new bridges and roadway alignments.
Lewis said that many detours were implemented throughout each phase of the project. “Some detours were temporary [overnight] and others were made to accommodate traffic for up to three months at a time.”
Phase 2 (October 2011 to October 2012) saw traffic rerouted at SR 69 to southbound I-17, using temporary detours and I-17 median crossovers built in Phase 1. Two lanes of traffic were maintained in each direction. New roadway lighting was installed.
Phase 3 (May 2012 to January 2013) included completion of Big Bug Bridge on I-17, construction of the east roundabout at Cordes Lakes Road and new ramps, as well as reconstruction of the existing interchange at I-17 south.
Phase 4 (March 2013 to June 2013) involves application of a layer of rubberized asphalt and final striping on I-17 and SR 69.
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