Section of I-10 in Phoenix celebrates 20th birthday

PHOENIX - It's probably the most well known stretch of freeway in the Valley or at least it is the busiest.

But there is more to this mile stretch of road than meets the driver's eye.

It even has a historic past.

"I'm sure there are a lot of drivers who don't even realize when the tunnel first opened and when that final mile was finished," said Doug Nintzel with the Arizona Department of Transportation .

The final mile to complete Interstate 10 in Phoenix was the Deck Park Tunnel.

"But it was also the final mile across the entire United States, so I-10 truly stretched from Los Angeles to Florida for the first time," Nintzel said.

Completed 20 years ago this week, it didn't come without controversy.

Downtown residents weren't too happy about a freeway through their backyards.

"The park idea did come along to say what about the idea of a depressed freeway with a deck on top and the park placed here," said Nintzel.

Hence the nickname, the Deck Park Tunnel.

It's really 19 different bridges put together with up to 8 feet of dirt on top.

All with some features behind the scenes to make it work.

"If you're driving through the tunnel on a daily basis you don't really think about some of the things behind those walls," Nintzel said.

Like giant fans used for ventilation when needed.

Or two control rooms to monitor traffic and safety systems.

And of course the challenge of keeping the lights on, three thousand of them.

All to move the 240,000 travelers a day who pass through quickly and safely for the next 20 years.