Why Phoenix Built A Tunnel, Then Immediately Abandoned It

I've driven through the Dean Lindsay Memorial Tunnel on Interstate 10 in Phoenix more times than I can count. A few months ago, I was driving into the tunnel and noticed a large gate and what appeared to be an entrance to another tunnel next to the entrance. What could it be?

This giant testament to structural engineering hides a secret, and it's hiding under the feet of the citizens of Phoenix. What is it, and why is it there? Let's take a closer look.

A Little About the Deck Park Tunnel in Phoenix

According to Wikipedia, the Dean Lindsey Memorial Tunnel, or Deck Park Tunnel, as it is more commonly known, is a "vehicular underpass built underneath Downtown Phoenix. It was built as part of Interstate 10 in Phoenix, Arizona."

The "tunnel" is actually a series of 19 side-by-side bridge overpasses divided into two tubes. Each has five one-way lanes and two emergency lanes running alongside it. Each tube can carry up to 16,000 vehicles per hour.

Origins Of A Big, Weird Idea

Back in the 1980s, Phoenix planners were feeling bold. To improve the traffic flow on Interstate 10, they designed this beautiful tunnel, but they didn't stop there.

They also carved out a full-blown underground tunnel running next to and under the flow of traffic. If you glance toward the left side of the tunnel as you drive in, you'll notice a large gate barricading the entrance to what seems to be yet another tunnel. But what is it, and why is it there?

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That gate leads to a full-blown underground bus terminal. It's right in the middle of the I‑10 Deck Park Tunnel.

The idea was simple: commuters would zip off the freeway, hop onto express buses, and glide into downtown. The space was fully built, lit, and outfitted with platforms and access points.

But then, it was never used. Not once. The grand vision fizzled before the first bus ever rolled in.

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A Tunnel That Time Forgot

Today, that “third tunnel” sits sealed behind chain‑link fencing, wedged between the eastbound and westbound lanes under Margaret T. Hance Park.

While you may have seen the fencing, most drivers have no clue it exists. It’s basically a concrete ghost town. ADOT officials say the space has been virtually untouched since the 1980s, quietly collecting dust while tens of thousands of cars roar past every day. It’s dark, it’s echoey, and it feels like the set of a low‑budget sci‑fi movie.

Why It Never Became A Thing

So why build a bus station only to abandon it? Classic story: funding dried up, plans shifted, and Phoenix’s transit priorities changed.

The tunnel was ready, but the connecting ramps and infrastructure were never funded, so they weren't built. Without those, the whole concept was basically a very expensive hallway to nowhere.

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ADOT leans into the mystery, joking about “secret labs” and “monstrous creatures” lurking in the unused bays.

At least they're leaning into the sci-fi story I'm already writing in my head about the forgotten underground bunker. Can someone call Hollywood? This is a story that's begging for the big screen!

Learn more about this fascinating secret on YouTube by News12: