Friday, December 4, 2009

December 4, 2009

Here are a few notes from the Community Board 8 Second Avenue Subway Task Force meeting that was convened earlier this week, on November 30th.

At the start of the meeting the MTA announced that Contract 1 (for the TBM Launch Box, tunnels from 92nd to 63rd Streets & shafts at 69th and 72nd Streets) is now 57% complete.

They didn't explain how they came up with this percentage, but even a casual observer of this project would have to wonder how they can actually be 57% complete with this contract - when they still have to (a) finish the TBM launch box, (b) assemble the Tunnel Boring Machine [TBM] at the site, (c) bore two tunnels from 92nd to 63rd Streets, and (d) remove the TBM from the site -- all by June 2011 (the current planned completion date for Contract 1.)

The MTA also said that the first two 72nd Street station construction contracts (for building demolition, station cavern mining, and heavy civil work) will be advertised [to potential contracting parties] in December.

S3 Tunnel Constructors said during their part of the presentation that the test blasting program (at the south end of the TBM launch box) was completed successfully during October and that they have now moved to "production" blasting. They expect that the blasting at the launch box site will be completed early in the 2nd quarter of 2010.

Here are 2 pictures, from the presentation, of the work site inside the TBM launch box.

under 92nd - looking SW (my guess)
The pile of rock in this picture gives us the hint as to the photographers location -- since the bedrock that is being removed from the site is only present in the southern end of the work site.

under 94th - looking S (my guess)
If you look carefully you can see the various utility lines that have been hung under the road decking structure above.

In the 2nd quarter of 2010 they expect to start assembling the TBM at the work site and they will also setup the vertical conveyor (referred to by some as a "muck tower") between 92nd and 93rd Streets. The vertical conveyor, which will be used to lift rock from the tunnel boring operation to the surface, will be setup between 92nd and 93rd Streets and it will extend about 25-30 feet above street level.

The TBM will be delivered in 50 truck loads, with 10-15 oversize loads coming in at night.

Assuming that they start boring the first tunnel in July 2010 (my guess) it should take the TBM about 14 months to complete its work. (this assumes that the machine can progress at a rate of about 1 linear block per week, which is what we were told in a previous CB8 SAS meeting.) If you do the math be sure to keep in mind that there are two tunnels, of approximately 30 blocks [each], that need to be bored.

The full 68-page presentation can be found on this link:
Construction Update and Ancillary Facility Design (69th and 72nd Streets)
Community Board 8 Second Avenue Subway Task Force - 11/30/09

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

"Implementation of the
Metropolitan Transportation Authority's Capital Plan"
Citizens Budget Committee - 10/09

I've added a new section now, with the latest SAS related posting from Benjamin Kabak's New York City Subway blog 2nd Ave. Sagas. Ben has been providing on-going commentary, via his blog, on the Second Avenue subway project since December 2006.

Megaprojects and the Second Ave. Subway
Second Ave. Sagas - 12/2/09

SAS Neighborhood Impact: Station Entrances
Second Ave. Sagas - 12/1/09

SAS Neighborhood Impact: Ventilation Structures
Second Ave. Sagas - 12/1/09

On building subway lines during recessions
Second Ave. Sagas - 11/13/09

Archive with all 90+ Second Ave. Sagas
postings on the Second Avenue Subway

Under News:
"Station Plans Move Forward"
Our Town - 12/3/09

"With new subway, massive eyesores"
The Real Deal - 11/30/09

"Co-op Boards Together vs. MTA"
Habitat Magazine - 11/25/09

"Now it's Second Avenue flood way"
NY Post - 10/30/09

"Bracing for 2nd Ave. Subway"
NY Post - 10/22/09

"Third dig on 2nd Avenue"
Skanska Worldwide - 2009

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A footnote:

I know that I'm way overdue for a posting with a fresh set of pictures. Sorry about the delay, but many other things have been taking up my free time over the past few weeks.

I hope to have a new set of pictures up in a few days - if the weather cooperates this weekend.

1 comment:

mdh said...

A couple of comments... first, thanks for your great and continual coverage of this project. As a resident at 69th St. & 2nd Ave. I have a pretty nice bird's eye view of the work going on down there but I rarely make it up to the 90s to see what is happening there.

Second, as someone who works in construction (though not on transportation projects) I actually can believe that Contract is 57% complete. The reason, I believe, is that the scope of work for Contract 1 is primarily labor. Building the launch box and shafts at 69th/72nd Streets are jobs that require lots of labor and -- by comparison -- relatively little materials. Boring the tunnels, on the other hand, requires a sizable investment in equipment (the TBM) with a considerable -- but comparatively smaller -- amount of labor.

It is likely that payment for the TBM itself has already been either partially or fully remanded, because the equipment has probably already been procured and fabricated. Often, boring machines are built specifically for a new project, and it wouldn't be possible to construct a TBM without payment for the people who spend time fabricating it. Although the TBM arrives at the site in pieces, a lot of work takes place before it arrives.

Finally, crews have been working in the 90s to prepare the launch box for years now, representing a massive effort and substantial amount of labor. By comparison, the labor required to create shafts at 69th/72nd Streets is minimal. Although much of the work remaining includes what we'd believe to be the "meat" of this contract (assembling the TBM on-site and drilling the tunnels themselves, then disassembling the TBM), due to the massive amount of labor already exerted it's not hard to believe that nearly 60% of this contract work has been complete.