D-Tour: O’Neill Tunnel

BOSTON (WHDH) - It’s a door on 93 south that tens of thousands of drivers pass by every day, but few ever get to open. But last week, Danielle Gersh got a look at what’s behind it.

For a better understanding of how Boston’s O’Neill Tunnel operates, Danielle had to start at the bottom – 100 feet below street level to be exact – in the room that handles any water inside the tunnel.

“There’s no such thing as a dry tunnel, so you have to manage the water,” Adam Hurtubise, a massDOT official, said. “We’re confident that it will handle any kind of weather event that would come our way.”

Just as cars are moving in and out of the tunnel, something else needs to be moving in and out too: air. There are 215 fans that circulate air in and out of the tunnels. When one is turned up to full blast, it has the power to carry someone out into the street hundreds of feet away.

The O’Neill Tunnel was constructed as part of the Big Dig. Its problems have made headlines over the years, but massDOT Highway Administrator Tom Tinlin says crews are always working to make sure drivers are safe.

“We inspect everything that’s in the roadway with our consultant teams every two years, everything above one’s head every six months,” he said. “You can’t pay too much attention to such a complex system.”

The next time you’re driving through one of the tunnels in Boston, take note of those tiles on the side of the road. If they’re brown, it means you’re under ground. If they’re blue, you’re under water.

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