PHOENIX – The Interstate 10 Deck Park Tunnel, a Phoenix landmark used daily by more than 200,000 vehicles, is turning 35.

The nearly mile-long tunnel, created by 19 side-by-side bridges between Third Street and Third Avenue, opened on Aug. 10, 1990, just north of downtown Phoenix. That followed three days of public events in the tunnel and above it in the new, 32-acre Hance Park created by the City of Phoenix.

Fast forward to last year, when the Arizona Department of Transportation dedicated the tunnel in memory of Dean Lindsey, a late ADOT civil engineer. It was Lindsey who, in the 1970s and ’80s, was tasked with managing development of several I-10 Papago Freeway projects in the downtown Phoenix area, including the tunnel.

Creating the Deck Park Tunnel Project was a monumental task. Construction workers placed 1,400 columns to support the bridge structures. Crews excavated 1 million cubic yards of soil and installed more than 100,000 cubic yards of concrete and close to 20 million pounds of reinforcing steel..

The tunnel is part of the Final Mile of I-10 – the last stretch of the interstate to open to traffic across the United States. Its opening 35 years ago at the Deck Park Tunnel completed 2,460 miles of I-10 across eight states, from Santa Monica, California, to Jacksonville, Florida.

A recent major upgrade was completed in 2021 when the tunnel’s original overhead sodium lighting was replaced by a modern LED system featuring more than 1,500 energy-efficient lights.