By Dani Weber
ADOT Office of Creative Services

Interstate 10 moves approximately 260,000 vehicles through the Phoenix metro area every day. It’s a vital link for commercial traffic traveling to and from California and New Mexico; for intrastate travelers going between Phoenix and Tucson; and for a respectable number of travelers going to and from many of Arizona’s southern towns and cities.

From California to New Mexico, it’s nearly 400 miles long and intersects with nearly two dozen highways or routes, including interstates 8, 17 and 19. If you wanted to discount as a statistical outlier the 881-mile stretch that runs through Texas (where everything’s just bigger anyway), Arizona could even claim to have the longest stretch of I-10. So, I-10 is arguable both huge and important, right? Well, there’s one particularly special stretch: the bit that runs through the Papago Freeway Tunnel in Phoenix.

Before we discuss how special this stretch of freeway is, we should straighten some things out:

• The Papago Freeway Tunnel is better known as the Deck Park Tunnel to Valley residents. Many residents don’t even know the tunnel has more than one name.
• It’s technically not a tunnel. The freeway actually travels through the underside of a series of 19 side-by-side bridges, which knocks it out of the FHWA definition of what makes a tunnel a tunnel. Residents call it a tunnel because, well, that’s what it feels like … and it’s a lot easier to call it that than the “Bridge Deck Park Underside.” It just doesn’t have the same ring to it.
• Also, the park above the tunnel is not called Deck Park, even colloquially. It’s called the Margaret T. Hance Park (or Hance Park for shorthand) in honor of Phoenix’s first female mayor. The “deck” in “Deck Park” refers to the fact that the park sits on the deck of the series of bridges.

To review: its official name is Papago Freeway Tunnel, but it prefers to be called the Deck Park Tunnel; it’s not actually a tunnel, but the underside of a series of bridges; and the park above the nontunnel isn’t actually named Deck Park, but rather Margaret T. Hance Park. So far it seems like the only thing special about this stretch of road is its apparent identity crisis. Is there anything about this multinomered nontunnel that we can trust?!

There is, as a matter of fact.

Commuters who travel through the tunnel every morning and evening may not realize that they’re driving across the final half-mile that completed the entire I-10 — the one that’s nearly 2,500 miles long and stretches from Santa Monica, Calif., to Jacksonville, Fla. This was the last piece of a herculean undertaking that took over 30 years to complete. No equivocation necessary on this one.

Here are a few facts you probably didn’t know about the Deck Park Tunnel:

• It has roughly 3,000 lightbulbs that ADOT crews change out three times each year.
• Four gargantuan fans are installed in each tube in case emergency ventilation is necessary.
• To keep the lights, fans and other features operational during a power outage, ADOT keeps a diesel generator fueled and ready to go.
• There’s actually a third, single-lane tube that runs between the east- and westbound tubes. This tube was meant to be an express bus lane, but it’s currently unused and gated off.
• Each tube can support 16,000 vehicles every hour.

Identity crisis notwithstanding, it turns out the Deck Park Tunnel is a respectable feat of engineering and maintenance!

Next month will mark 22 years since its completion. It’s not really a milestone, but how about we celebrate anyway? We could all hold our breath and make a wish at the same time!

With roughly 240,000 vehicles driving through it each day, the I-10 Deck Park Tunnel needs the night off every once in a while for a good, thorough scrub!

Just about every four months, the tunnel is closed to traffic in order to allow crews the chance to wash the walls, maintain the ventilation systems and check on the tunnel’s 3,700 light fixtures (about 150-200 light bulbs are changed out each quarter!).

Crews typically complete the cleaning over two nights. That means only one side of the tunnel needs to be closed each night … leaving the other direction open to traffic.

Cleaning the white tile walls not only gives the tunnel a fresh look, but it also helps brighten things up a bit.

“We’re washing the walls and keeping them clean so the light bounces off the wall onto the deck so it makes a better drive through,” says ADOT Highway Operations Supervisor Ed Walsh in the video above.

A little history …

For anyone fairly new to the Valley, it might be hard to believe that the Deck Park Tunnel represents part of Interstate-10’s “final mile.”

It was 21 years ago this month that the tunnel was completed, closing up the last remaining gap in the 2,460-mile-long interstate that stretches across the country.

The project was a big one because the path of this final mile was in between two historic Phoenix neighborhoods.

Designers came up with an innovative plan to limit the impacts on the communities. Builders dug out the freeway’s path, put in the 10-lane roadway and covered up the top of the road with a deck made out of 19 side-by-side bridges, created a tunnel and then built a 30-acre city park on top. The project took more than five years to finish and cost an estimated $700 million.