NY1's Bobby Cuza got an exclusive look at the progress on the 7-line extension project this week.

Construction crews are digging two huge shafts through which they will lower tunnel-boring machines as part of the MTA’s 7-line extension serving Hudson Yards.

The machines will arrive early next year and will help dig a new subway tunnel, that will extend the 7 train from Times Square to 11th Avenue and down to 34th Street.

Across the street from the Javits Center, work is underway on a second site, to excavate the cavern that will become the 34th Street terminal. Once home to the famed Copacabana nightclub, the southeast corner is also now MTA property, and will become the main station entrance.

While the 7-train terminal will be at 34th Street, the tunnel will extend all the way to 26th Street and 11th Avenue in order to provide extra storage space for trains.

"We're using the two tunnel areas past the terminal station as what we call 'lay-up tracks,'" explained Joseph Trainor of MTA Capital Construction. "We'll be able to store six full trains in there."

While there have been concerns about cost overruns on the project, the main construction contract has already been awarded, which means tunneling work is all but guaranteed to be completed.

"The work that we're doing now, this contract, is $1.14 billion. It's 65 percent of the job," said Trainor. "So, I mean, in one fell swoop, we're going to do a majority of the work in the next several years."

The MTA still has to find companies to construct the tracks, signals, and station interiors. Officials say the whole project is slated to be finished by 2013.

- Bobby Cuza