NEW YORK (CBSNewYork) – The highly anticipated Second Avenue Subway has hit another key milestone.

The cavern for the 86th Street station was completed on time, the Metropolitan Transportation Authority announced Thursday.

Work on the $332 million station began back in 2011 and required extensive excavation as well as the creation of a huge concrete shell to encompass the station.

“We have now completed 76% of the work needed to build Phase 1 of the Second Avenue Subway. This project will benefit residents of the Upper East Side in so many ways,” said Michael Horodniceanu, President, MTA Capital Construction.

There’s still work to be done on the stations air supply, elevator and escalators, among other things.

Phase I of the Second Avenue subway project, which includes stations at 72nd, 86th and 96th Streets is expected to serve 200,000 riders a day, relieving congestion on the Lexington Avenue line. It is expected to be completed in December 2016. It will function as an extension of the Q train.

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