Sunset Road connection project between Silverbell and River underway

Another major Regional Transportation Authority-funded roadway corridor project is in the early stages of dirt flying.

While preliminary work on Sunset Road, Silverbell Road to River Road, has been in progress for some time, the real work is set to begin on part of RTA ballot Project No. 8.

Project overview of Sunset Road project. The current phase will connect Sunset to River Road east of Interstate 10.

“This is a complicated project that requires a lot of interagency coordination. It’s exciting to see all that effort start to take shape for the improved mobility of people in the community,” said Rick Ellis, director of transportation services with Pima Association of Governments, which manages the RTA.

The final segment of this project will see construction of a new road connecting Interstate 10 to River Road, including bridges over the Union Pacific Railroad and the Rillito River. The project is designed as four lanes with a median, signalized intersection at River Road, bike lanes, sidewalks and a multi-use path.

The voter-approved 2006 plan provides $12.7 million in RTA funding with an additional $10 million coming from Pima County and the City of Tucson.

The Sunset project is benefitting from a unique opportunity since project team members and leaders within the city, county, ADOT and RTA all worked together for the project to be integrated with ADOT’s mainline Interstate 10 widening project. This approach has not only provided better overall efficiency but allowed both projects to be completed simultaneously.

This portion of work is the second phase of the overall RTA-funded project that reestablished connectivity between Silverbell Road to the I-10 frontage road. That western portion of the project was completed in 2017, which included rebuilding of Sunset Road between Silverbell Road and the frontage road and reconstruction of a bridge over the Santa Cruz River. A former bridge was lost in the catastrophic floods of 1983, one of the worst flooding events the region has experienced in the modern era.

As coincidences sometimes go, the 1983 flood wasn’t the first time a major flood tore through the area and caused major damage. Preliminary work on the first phase of the project in 2015 revealed evidence of another flooding disaster, this one thousands of years old.

Areas along the Santa Cruz and Rillito rivers have long been known for an abundance of archeological remains, as the rivers supported ancient agricultural communities throughout the region. But what workers uncovered in a desert field south of the current Sunset alignment thrilled even the most experienced archeologists: human footprints.

Further excavations revealed numerous sets of adult, child, and even domesticated canine footprints in what was once a thriving farm fed by canals from the Rillito. Analysis dated the settlement to about 1000 B.C. Archaeologists believe the footprints dried in the mud of an irrigated field that was later covered with sediment following a major flood event. It’s possible the inhabitants abandoned the area when flooding irreparably damaged the network of canals and earthen floodgates that fed the fields.

The settlement was mapped, artifacts cataloged, and casts of the footprints made to preserve the find for the ages.

“The project was unique from the very beginning due to all the challenges that needed to be addressed.  Finding the footprints from so long ago made the project special as well,” Ellis said.

Work on the current project started in February and is expected to be complete sometime in late 2025.

A project website is available on the Pima County Department of Transportation website. The page also includes an interactive map and links to project renderings. Additional information is available at the ADOT project page.