Friday, June 18, 2010

SAS TBM Now in Full Production Mode

The TBM mining operation for the Second Avenue subway is now in full production mode, as of yesterday.

This means that the testing of the TBM is now complete, the kinks have been worked out, and the conveyor system (to get the mined rock out of the hole) is working as designed.

For the time being, the MTA's contractor, S3 Tunnel Constructors, will be mining the west tunnel (using the TBM) 5 days a week, 24 hours a day. It is expected that the TBM will move south under Second Avenue at a rate of about 50 linear feet per day.

Note that even though underground mining will take place at all hours, the vertical elevator will only be used during the authorized hours for working at street level. During those hours of the day when it cannot be used, rock from the mining operation (which is referred to as muck) will be stored underground in something called a muck bin until it can be brought up to street level to be trucked away.

As of today, the TBM is located about 50 feet below the road surface, at a point between 91st and 92nd streets - on the western side of Second Avenue. You can hear it faintly, when it is in operation, if you place your ear against the wall of a building that is nearby.


The images below show the muck, from the TBM mining operation, being loaded into a truck by the vertical elevator system. All of the images were taken this morning between 7:15 and 7:45 a.m.

The workers shown here are waiting for the arrival of an empty truck. While they wait, mined rock (muck) is being loaded into the hopper above.

The truck has just pulled into the loading area and a worker is about to open one of the two chutes.

Once the chute is opened, the truck quickly starts to fill. (I'd estimate that it takes no more than about 20-30 seconds to fill the truck.)

The workers have just closed the chute and they are preparing to climb into the rear of the truck to level the load.

This is a close-up shot of the muck that has just been loaded into the back of this truck. (The material if much finer than I thought it was going to be.)

The worker here, on the left, is using a shovel to level the load.

The truck has just pulled away so one guy gets left with the job of sweeping up the spillage, which was minimal.


Here's a listing of the recent additions
to the right-hand column of The Launch Box

As 2nd Ave. businesses suffer, MTA toes the 2016 line
2nd. Ave. Sagas - 6/15/10

MTACC Project Update - 2nd. Ave. Subway - June 2010
A two-page report to the
Capital Program Oversight Committee of the MTA Board of Directors
by MTA Capital Construction
June 2010
MTA CPOC Report - 2nd. Ave. Subway - June 2010
A nine-page report to the Capital Program Oversight Committee of
the MTA Board of Directors
by the MTA's Independent Engineer Consultant McKissack+Delcan JV
June 2010

I exported these two MTA reports to Scribd to make them easier to read. If you wish to read the full 76-page Capital Program Oversight Committee (CPOC) report you can find it on this web link:
MTA CPOC Report - June 2010 (47 Mb)

If you can't see these reports on your screen then click on the web link above the report.