Monday, August 2, 2010

A TBM on the Move


Work underground is progressing and the TBM, as I type this posting, is boring its way south, deep under Second Avenue.

From the MTA's perspective the TBM officially started excavating Tunnel No. 1 (the west tunnel) on Tuesday, June 8th - about 7 weeks ago. Since then the cutterhead of the TBM has carved out 657 linear feet of tunnel, as of last Thursday, July 29th.

The MTA has said that the first 700 feet or so of the TBM's operation would be the test period - when they knew that it would be a challenge to get the various systems, on the newly assembled machine, working properly together. Considering the problems over the past 2 months, some might say that this was a bit of an understatement.

One senior official inside the MTA has even gone so far as to say that during the early going they have been "plagued with technical problems" - electrical problems, problems with the electronics, problems getting the grippers to apply the proper amount of force, and problems with the drive shaft on the TBM, that ultimately had to be replaced - as well as the numerous problems with the high-speed conveyor systems (with being parts flown in from Switzerland.)

And then there was the poor rock that they encountered for the first 200 feet of so of TBM mining (between 91st and 92nd streets.)

The rock in this area under Second Avenue is heavily fractured and it contains numerous faults and seams. The TBM that is being used on this project has a tough time working its way through fractured rock because the grippers (the arms that push the TBM forward into the rock face) can't properly grip the rock without crushing its structure - and if the grippers crush the structure of the rock behind the cutterhead you don't have a tunnel that can support itself.

The contractors have also had to install steel rings to support the tunnel in this section. I'm told that the MTA was also concerned about the possibility that the grippers might damage the integrity of rock between Tunnel No. 1 and what will become Tunnel No. 2 in this area, by applying too much force on the rock, so it was very slow going for the TBM for the first few weeks.

Then there was the runaway TBM probe drill that surfaced on Second Avenue back on the morning of July 8th.  This incident cost a considerable amount of time due to the ensuing investigation.

But now the MTA believes that the contractor has worked out the last of the kinks with the systems on the TBM and the machine has moved passed the area of poor rock in the low 90s.

On July 24th, when the contractor worked on a Saturday to catch up a bit, they had the first good production day of mining with the TBM. (I'm not exactly sure what this means in terms or production, but one might guess that on this day the TBM mined about 50 feet of the new tunnel.)

A side note about the expected production rate of the TBM -- the contractor has the machine scheduled to operate 24 x 5 at the moment (i.e. 24 hours a day, 5 days a week [M-F]).  They [the contractor] have said that the TBM should be able to mine at a rate of about 65 feet per day, but for planning purposes the MTA has used a rate of just 50 feet a day, to be conservative.  Needless to say, we're still waiting to hear (officially) about a 50-foot or better production day.

But with all of that said the  MTA remains confident at this point that the TBM will finish its 7,200 foot run to 65th Street by early January 2011.  At that time the TBM will back up to the launch box and start mining Tunnel No. 2 (the west tunnel).

In other news --
  • MTA sponsored repairs are underway in the buildings between 95th and 96th streets - and I'm told that the residents who were temporary relocated at 1723 Second Avenue were able to move back into their apartments on Saturday, July 24th. (These are some of the buildings that the MTA and the DOB had determined needed to be worked on to repair a number of structural conditions.)
  • A total of 88 buildings, near where the 72nd Street station will be built, have now been surveyed by the MTA's contractor to check for structural issues, and a total of about 20 of these buildings were characterized as "problematic." The MTA is now working with Department of Buildings to determine how much repair work needs to actually be done by the MTA. The survey also showed that 4 of the buildings required urgent attention due to structural deficiencies that the survey identified. The MTA is "cautiously optimistic" that they will not have to temporary relocate any residents in this area while any necessary building repairs are made.
  • The MTA is now in the process of qualifying the 2nd lowest bidder for the 72nd Street Station Cavern Mining Lining and Heavy Civil contract, which is known as Contract C-26007. The lowest bidder, OHL/Tully Cavern JV, who had bid $319,229,925 has "declared a mistake" [with their bid] and they apparently are no longer being considered for this contract. OHL/Tully Cavern JV had bid $127 million (30% less) less that the 2nd lowest bidder SSK Constructors JV, which I understand is a joint venture between Schiavone Construction and J.F. Shea Construction.

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Now on to a few new images.


7/31/10
Just N of 72nd Street - looking NW

What you see here is top of the [now complete] access shaft at 72nd Street. The top of the shaft,as shown in this image, has been covered over with concrete decking.

This shaft will be used later in the project during the mining and construction of the 72nd Street station. When the project is complete the shaft will be filled in and covered over with a new road surface.


7/31/10
72nd Street - looking N

Another view of the completed shaft at 72nd Street.

Work on the 69th Street shaft is still on-going, but I've been told that the blasting work at this location has now been completed.

Note the colored sign on the right side of the image. It say that "work on this project is scheduled to be completed by [the] summer of 2011."  This statement is a bit misleading (for the general public) in my view since work at this location is actually scheduled to continue until late 2013 while they mine and construct the 72nd Street station.

Oddly the sign also make reference to the 96th Street station.  People on the street who view this sign might ask themselves, "what part of the 96th Street station is being constructed here at 72nd Street?"


7/31/10

This is the front end of a 30" ball valve that is being prepared for installation. Most likely it will be used to regulate a new gas main that runs under Second Avenue.


7/31/10

Another view of the same valve.

Short sections 30-inch pipe, each about 4 feet long, have recently been welded to the valve on the left and the right.  (the valve itself is the black round section in the middle, with the actuator on top.)



7/31/10

This is a closer view of weld between the pipe and the ball valve.



7/31/10

And a much closer view of the weld.  To be sure, this weld is the work of a high skilled craftsman.




7/31/10
83rd Street - looking W

An extensive amount of utility relocation is on-going in this area as one can clearly see in this image.


7/31/10

Two sections of cast iron pipe, an old fire hydrant and a pigeon are shown in this image.


7/31/10
Just south of 91st Street - looking NW

Workers have recently removed the road surface from this location in preparation for the "ground freezing" procedure that will be setup at this location before the TBM starts to mine Tunnel No. 2 (the east tunnel) in early 2011.

The ground on the east side of Second Avenue between 90th and 92nd streets (approximately) must be "frozen" because the structure of the rock at this location is too weak for the TBM to operate properly.


7/31/10
btw. 93rd and 94th Streets - looking W

This large container caught my eye when I walked by it on Saturday.  According to the label on the side, the blue liquid is Midfloc 1315L, an industrial chemical compound called Anionic Flocculant.  This product is used to remove suspended particles in waste water. (if you click on the chemical name there is a brief video that shows how this product works.)


7/31/10

This is a view of the undercarriage of the Liebherr HS 885 crawler crane that is currently located between 94th and 95th streets.


7/31/10

And this is a closeup view of the mechanism that is used to rotate the crane,



7/31/10
95th Street - looking N

This is a section of newly completed sidewalk on the east side of Second Avenue.  It may not look very exciting, but for the past few months residents in this block have had to use a temporary protected walkway that had been setup in the middle of Second Avenue.


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A footnote:
A few people have asked me why I don't have any pictures of the work that is taking place down in the tunnels.  The simple answer is that don't have access to the work site, above or below ground.

With that said, if any of the workers or contractors wish to share any of their images that they have taken of the work taking place underground please feel free to send them to me via e-mail.  Or if they're posted somewhere on-line please just tell me where to find them (e.g. on the Flickr web site). 

You can find my e-mail address in the right-hand column of this blog.

Ben


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

"Feds See 'Grim' Delays, Overruns on Second Ave. Subway, East Side Access"
By Eliot Brown
The New York Observer - 7/9/10

"New York Truck Companies Investigated for Fraud"
By William K. Rashbaum
The New York Times - 7/9/10

"Equipment failure delays 2nd Ave. subway AGAIN!"
By Pete Donohue
Daily News - 7/27/10

"Picture This, and Risk Arrest"
By Jim Dwyer
The New York Times - 7/27/10
An interesting article about what happened to a guy who decided to take a few pictures of Amtrak trains at New York Penn Station.  (This isn't really related to the 2nd Avenue subway - but it is interesting for photographers like myself.)

"Business Slides on Second Avenue As Subway Construction Drags On"
By Joseph De Avila
The Wall Street Journal - 7/31/10


Delays, overruns again plaguing Second Ave. Subway
2nd. Ave. Sagas - 7/9/10

Inside the subway station of the future
2nd. Ave. Sagas - 7/15/10

Underneath 2nd Ave., a TBM struggles to move forward
2nd. Ave. Sagas - 7/28/10


The Blog Below
An interesting blog about subterranean spaces and tunnels.  Unfortunately the author stopped posting in late 2008.

The Underground Construction Association of SME
The home page of the Underground Construction Association of the Society of Mining, Metallurgy and Exploration.


Blog
the Wikipedia entry for the word "blog".


Last Reported Location of the TBM
~20 feet north of 89th Street
as of Thursday, July 29th

TBM Run No. 1 (west tunnel)
92nd Street to 65th Street
7,200 linear feet
40 foot starter tunnel
657 feet mined w/TBM to date
6,503 feet to run

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