The MTA's massive East Side Access project, which will connect the Long Island Rail Road to Grand Central Terminal, has been in the works for years, from getting federal funding in 2006 to being really overbudget this year. At any rate, it's the country's largest infrastructure project which will—hopefully—relieve congestion at Penn Station as well as crosstown congestion. Plus, it's really awesome how it's being built.

Today, the MTA announced that sandhogs "broke through the final piece of reinforced concrete separating newly built tunnels in Queens from newly built tunnels in Manhattan. In so doing, they created a continuous tunnel running more than 3½ miles from a cavern 12 stories underneath Grand Central Terminal to four concrete-lined, 22-foot diameter tunnels just feet below the Sunnyside rail yard in Queens that will soon be connected to the Long Island Rail Road main line." This connection is under Northern Boulevard in LIC.

MTA Chairman Joseph Lhota said, "For the first time since the East Side Access project began, there is now a continuous path through newly built tunnel from Queens to the East Side of Manhattan. This the path Long Island Rail Road trains will follow when this project is completed."

The MTA also has other interesting factoids:

Not only does this segment of tunnel need to bear the weight of Northern Boulevard, a busy 6-lane arterial truck route leading to the Ed Koch-Queensboro Bridge. It also needs to support the four-track IND subway trunk line underneath the roadway that carries the E, M and R subway trains, as well as that of the elevated BMT Astoria Line, which carries the N and Q subway trains.

Project workers had to drive a new set of foundation pilings into the ground to temporarily support the Astoria Line tracks and elevated structure during the construction of the tunnel. They then jacked up the line ever so slightly in order to relieve its permanent foundation supports of the line’s weight, and shift the weight to the temporary supports. Then, they cut into the permanent foundation, which had been protruding into the right-of-way where the new tunnel is being built. In later phases of construction, workers will restore the subway line to its permanent foundation, which has been modified to rest on top of the newly completed section of LIRR tunnel. The tunnel has been engineered to carry the weight...

Because the ground is soft at this site and difficult to control during excavation, it has been frozen to allow for increased control and rigidity. In order to further ensure the continued stability of the nearby ground, the tunnel has been divided up into seven horizontal segments, or “drifts,” which are arranged length-wise and stacked into three columns. Each frozen drift is being excavated separately, and the one completed today is the southernmost, top-most one.

To progress! And taking the party train to Grand Central.