DSCN2064, originally uploaded by robert the bear

Last week, the massive Tunnel Boring Machine (which is similar to the TBM above) began tunneling through the Manhattan Schist from the bulkheads of the existing tunnel at 2nd Avenue and 63rd Street (see map) on its way toward Grand Central Terminal. This marks the next phase of the MTA’s East Side Access project which aims to bring Long Island Railroad service to Grand Central. See the below isometric view of the Manhattan Tunnel Alignment:

From the press release:

The $10 million, 200-ton TBM arrived in pieces earlier this year, which were lowered into the 63rd Street tunnel in Long Island City via a massive excavation. The pieces were then transported through the tunnel, under the East River, to a “launch box” under 63rd Street and 2nd Avenue. The TBM was assembled in the launch box and began testing earlier in the fall, and has traveled approximately 500 feet to date. It is now digging its way toward Grand Central at approximately 50 feet per day, first moving east along 63rd Street and then curving down Park Avenue to Grand Central. A second TBM arrived in September and will begin digging a second tube for the project later this month.

The new facility will be an eight-track terminal, split into two four-track (two-over-two) caverns. This arrangement is the most economical both in terms of engineering and operations. The new terminal will be accessed by a concourse constructed in space currently occupied by Metro-North’s Madison Avenue Yard.

You can see photos of the lowering of the East Side Access Tunnel Boring Machine last June and read all about the East Side Access project.