CHECK THIS OUT: 17 secrets of the Eisenhower Tunnel and Johnson Tunnel

CLEAR CREEK COUNTY, Colo. - Every day, thousands of people drive through the Eisenhower Tunnel and the Johnson Tunnel on Interstate 70 in the mountains. But did you know there are dozens of highly-trained workers behind the scenes keeping you safe as you drive the 1.7-mile tunnels?

You've likely seen the signs that tell you the speed limit is 50 mph, but have you spotted the fire exits? The crossovers? The booth where someone can sit and monitor traffic? Let's go inside the tunnels!

Secret #1. Sidewalks. Yes, there is a sidewalk on each side of the tunnel. Workers use them, but you can't walk it or bike it. CDOT employee Bob Hammond, seen walking here, says he prefers to face traffic when he has to walk into the tunnel. 

Secret #2. Phones. Notice to Hammond's right, there's a box on the wall that says "phone." Yes, there is a phone inside. You can use that phone to call the workers inside the tunnel.

However, you don't have to call the workers. They can see you!

Secret #3. Cameras. CDOT has cameras every 850 feet throughout the tunnel and the workers are watching everything going on!

Secret #4. Control room. Inside the tunnel walls is a control room where two workers are always on staff to monitor a wall of cameras in both tunnels.

Secret #5. Carbon monoxide detectors.

Those workers are not only monitoring the vehicles driving through the tunnel, they're monitoring an important number -- carbon monoxide levels. As you drive through the tunnels you may spot the CO detectors in the tunnels.

Secret #6. Pulpits. If you're in the passenger seat, look closely as you travel through the tunnel for a booth set in the wall with stairs. Any guesses what this "pulpit" was used for?

Answer: When the Eisenhower Tunnel was first opened in 1973, they didn't have a camera system, so workers sat in these booths and watched traffic in person. Fortunately, that didn't last long. Within a year, the camera system was running and workers were able to get out of these small booths.

Secret #7. Fire exits. If there's a fire in the tunnel, there are emergency exits for people, but not your vehicle. If there's a fire, workers will stop traffic and turn on strobe lights to direct you to a fire exit.

Secret #8. Crossovers. If you ever need to use the fire exit, open the door and you'll find yourself inside a lighted walkway that leads to the other tunnel so you can escape.

However, if your car breaks down in the tunnel, don't get out of your car. The workers will know immediately that you're stuck and will put a message on a lighted board that says, "stay in your car, help is on the way."

Secret #9. Firefighting fleet.

How do they fight a fire at the tunnel? Most of the workers at the tunnel are trained as firefighters and they have fire trucks inside the tunnel ready to be used. And they do get used.

"We average three car fires a year inside the tunnels," explained retired maintenance supervisor Michael Salamon.

Secret #10. Fire extinguishers.

As you drive through the tunnel, you may see boxes with the word fire above them. Those are fire extinguishers.

Secret #11. Fire hydrants.

In the tunnel, you may notice some red lines on the wall occasionally. That typically marks the location of a fire hydrant, so workers can find them easily. In one tunnel, the hydrants are buried in the ground. In the other tunnel, the hydrants in the sidewalk. There's a hydrant every 250 feet.

CDOT has purchased a new fire suppression system for the tunnels. Installation work will begin next year.

"It will buy us time," Salamon said. "It will keep the heat down, so we can respond."

Workers at the tunnel have a lot of jobs.

Secret #12. Spring cleaning.

In addition to being firefighters, workers at the tunnel are also cleaners. Ever noticed how dirty the walls get in the tunnel?

You can really tell the difference between a clean wall and a dirty wall when a panel gets replaced. Workers use a special tanker to wash the tunnel walls twice a year. Salamon says they used a mixture of heated water and soap and a scrub brush, like a car wash, to clean the walls. The process takes about two weeks.

The walls are typically cleaned in May and again in the fall.

Secret #13. Light bulbs.

Another maintenance job is changing the light bulbs. There are 2,800 light bulbs per tunnel. Have you noticed there are two kinds of white, overhead lights inside the tunnel?

There are HID (high-intensity discharge) lights that gradually ramp down as you go into the tunnel and gradually ramp up as you leave the tunnel.

Salamon said the burned out lights are changed twice a year.

Secret #14. Ventilation.

As you drive toward the tunnels, look at the roof.

See those big purple things? Those are part of the ventilation system. There are seven on each side of the tunnel to move the exhaust air. Here's what one of those exhaust fans looks like inside.

Secret #15. Power.

The Eisenhower Tunnel has its own power substation. The tunnel gets power from Lake Dillon and Georgetown.

Secret #16. Water. The Eisenhower Tunnel has its own reservoir and water treatment plant to provide water for the staff bathrooms and for drinking. We didn't get a photo of the reservoir since it's underground.

And Secret #17. The westbound bore/Eisenhower Tunnel is the highest vehicle tunnel in the world at 11,155 feet, according to CDOT.

While the tunnels were built in the 1970s, they're still pretty fascinating today!

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