Sunday, January 30, 2011

A View Down Below, Part 2

This is the 2nd half of the the image set that
was posted on The Launch Box last weekend.

The 1st half of this set can be found on this link:
"A View Down Below - January 23, 2011"

All of the images shown below were taken on January 18, 2011.

Note that you can left-click on any imageto view it in high-definition format.

A rather dramatic image of a group of Sandhogs working in the very confined space near the head of the tunnel boring machine (TBM).

In this image, you can see the rear support legs of the TBM in the foreground on the right and the left.

Courtesy of The Robbins Company

This diagram, which was also shown in the original posting, details the major components of the Main Beam TBM that is being used to bore the two tunnels for Phase I of the Second Avenue subway.

A short video showing how a TBM of this type works can be found on this YouTube link: Robbins Main Beam TBM Boring Cycle.

In this image, you can see one of the gripper shoes of the TBM.

The equipment shown


A note - somehow the rest of the posting is now missing. When I have some time I will attempt to recreate it.

Sunday, January 23, 2011

A View Down Below, Part 1

Let's take a walk down Second Avenue in a way you never have before - underground, inside the west tunnel of the Second Avenue Subway.

A few notes before you start this journey:

- The work that you see here is part of Contract 1 (referenced as Contract C-26002 by the MTA) of Phase I of the Second Avenue Subway project. This contract was awarded in January, 2007, to Skanska USA Civil, Schiavone Construction, and J.F. Shea Construction, in a joint venture under the name S3 Tunnel Constructors.

- The work in the tunnels is performed by members of
Laborers' Local Union No. 147 (a.k.a. the New York City Sandhogs).

- All of the images shown below were taken on January 18, 2011,
unless otherwise noted.

Note that you can left-click on any image
to view it in high-definition format.

An aerial view of a portion of the Tunnel Boring Machine (TBM) launch box site - looking south towards the tunnels. (The launch box extends from a point just south of East 95nd Street to a point just south of East 92th Street.)

The west tunnel, which is currently being mined by the TBM, is visible in this image on the right.

The tunnel on the left is the starter tunnel for the east tunnel. Mining of this tunnel, with the TBM, should start in March 2011.

The narrow gauge tracks that you see in this photo are not the tracks of the future Second Avenue subway. These tracks are used by the muck trains that transport the rock produced by the mining operation.

This is a another view of the launch box, looking north. The wall to the north in this image is about three blocks away.

The cylindrical struts that you see in this image help to support the east and west walls of the launch box.

This shot shows the launch box as seen from ground level, looking south.

Notice the tall rubber boots being worn by the workers. These boots are necessary for journeys into the tunnel because the tunnel is very muddy, as you will see in the images that follow.

At the moment, this tunnel extends from a point just south of 92nd Street to approximately 67th Street - a distance of just over one mile.

This is a view just inside the tunnel looking south. The tunnel has been mined to a diameter of 22 feet. At this location, the floor of the tunnel is about 75 feet below the street level.

The large yellow pipe on the ceiling carries fresh air to the head of the tunnel.

The cables on the right carry electricity for the TBM, and for the tunnel lighting. Additional cables are used for communications.

This is a view from deeper inside the west tunnel, now looking north back towards the launch box. This photo was taken roughly underneath 84th Street.

Notice how smooth the walls of the tunnel are in this area. This is very high quality rock which means it was probably quite easy for the TBM to cut through.

Note the three pipes on the right side of the tunnel in this image. Two of the pipes are used to carry water and air towards head of the machine, and one of the pipes is used carry water back out of the tunnel.

Also note the spray painted notation, "84th," on the left hand side of the tunnel. The cavern for the 86th Street station will eventually be mined just north of this location.

Clearly some of the Sandhogs on this project are New York Giants fans - but a reliable source has told me that most of them are actually New York Jets fans.

This is interesting shot. It shows an area in the tunnel with weak rock.

To buttress the weak rock, a set of steel ribs and mesh has been setup at this location to provide additional stability, and to protect the workers.

When the workers come across rock like this they must move the TBM forward very slowly, sometimes just a few feet per day.

When the TBM finally finishes its job and is backed out of the tunnel, the contractor will add a one foot thick precast concrete lining. The will be achieved by using a traveling form.

The contractor will pour the concrete for the tunnel invert and when the required strength has been achieved they will strip the forms and move them ahead.

Then another traveling form will be erected in place for the arch, the concrete will be pumped in, and when the strength is obtained the form will be stripped and moved ahead. (Stripped is a term in the industry to remove the forms, whether they be wood or steel, and move them ahead for the next concrete placement or pour.)

The material you see on the right, which looks somewhat like clay, is made up of fine rock particles that have fallen from the muck train that travels on this track.

The sandhogs regularly must shovel this heavy, wet material out of the bottom of the tunnel in order to keep the track bed clear. They generally do this during periods when maintenance is being performed on the TBM (i.e. when there are no muck trains moving on this track).

Now you are standing at a point that is approximately under 80th Street. The small engine that you see here is used to pull the muck train.

Note the very high quality rock in this section of the tunnel - no steel ribbing in sight.

Here on the left you can see some of the hopper cars that are used to transport rock out of the tunnel.

In the distance, you can see a muck train that has been positioned inside the TBM - waiting to be loaded loaded with rock from the mining operation.

Here is another view of the hopper cars waiting to be backed into the TBM.

Notice the steel ribs in this section of the tunnel. They must have hit lots of weak rock in this area.

This is the end of the conveyor belt, mounted on the TBM, that transports mined rock to the waiting hopper cars.

This is a close-up shot of the muck produced by the mining operation.

This is a view, looking north, from inside the TBM.

The front of the TBM, where the cutterhead is located, is now starting to come into view - on the left.

In the foreground, you see part another part of the conveyor system.

This is one of the Total Stations that allow the TBM operators know exactly where they are, and the precise direction that they are headed.

The stations are able to calculate distances and angles with a very high level of accuracy by shooting a laser toward a set of retroreflector targets that are mounted on the front of the TBM.

You can be sure that nothing like this was being used when the first tunnels of the New York City subway system were constructed over 100 years ago!

Courtesy of The Robbins Company

Before going any further, here is a diagram that details the main elements of the machine.


And this image, which was taken about seven months ago inside the launch box, provides you with a clear view of the front of the TBM .

Back in the tunnel, you can see here on the left a Sandhog working on the left gripper shoe of the machine.

And here you are -- right behind the cutterhead of the Second Avenue subway TBM.

The Sandhogs here are clearing away loose rocks while the machine is not in operation.

Note the propel cylinders on the upper left. These cylinders are used to push the cutterhead, with incredible force, into the rock face in front of the TBM.

A closer view of these cylinders.

And in this shot, you again see a group of Sandhogs working to install steel ribs right behind the cutterhead of the machine.

You have scene here that, in some ways, resembles an operating room: intense overhead lighting and a very experienced team focused on a single task.

It's almost as if the Sandhogs do not need words to communicate with one another. It is similar perhaps to the way that track gangs on the railroads used to work together in the days before machines did most of the heavy work.


The 2nd half of this image set can be found on this link:
A View Down Below, Part 2 - January 30, 2011

Monday, January 17, 2011

A View from Above

On Saturday afternoon, I was invited to visit the rooftop of 233 East 69th Street to take, for this blog, a few pictures of one of the active work sites on Second Avenue.

The images that follow were taken from the the rooftop terrace of this 16-story apartment building, which is located on the west side of Second Avenue between 69th and 70th streets.

The contractor working at this location, SSK Constructors JV, is preparing to start mining the underground cavern for the new 72nd Street station. SSK Constructors is a joint venture made up of Schiavone Construction, J.F. Shea Construction, and Kiewit Infrastructure Corp.

Click on the picture above to view a larger copy of this stitched image. To view the original high-definition image, which is 6,834 x 2,444 pixels, click on this link to my account on Flickr.

In this image, you can see the active work site - with 69th Street on the right and 70th Street on the left.

If you look closely, you can see three groups of SSK workers on the job site.


This is closer view of the southern end of the work site at this location. (69th Street is on the right in this image.)

Underneath the steel decking (shown above) is one of the two 60-foot deep access shafts that was dug out by S3 Tunnel Constructors earlier. The other access shaft is located just north of 72nd Street.

SSK will use these two shafts for access to a cavern that eventually will be blasted out of the bedrock below Second Avenue.

I'm told that they will mine the cavern for the station by first blasting out a pilot cut at the top of the cavern. Next, they will mine 2 slash cuts on the right and left of the pilot cut.

Then, after the TBM has mined the 2nd (east) tunnel, later this year, they will mine the station cavern down to the floor level of the track tunnels.


This is a closer view of the northern end of the work site at this location. (70th Street is on the left in this image.)


This is a view looking north on Second Avenue. The 72nd Street access shaft is located just to the north of the crane shown in this image.


This is a closer shot of the 72nd Street access shaft work site, to the north on Second Avenue.

If you enlarge the image you can also see work sites between 78th and 79 (in the middle of Second Avenue) and near 83rd Street (on the west side of the avenue).


And up on 92nd Street...

92nd Street, NE corner - looking E

This is the recently activated ground freezing plant that is just to the east of Second Avenue.

The plant produces a chilled calcium chloride brine that is pumped through a network of pipes that has been installed in the drilled holes on Second Avenue near 91st Street. The ground near 91st Street & Second Avenue must be frozen before the TBM can mine the east tunnel because of the weak rock structure below ground.

A brief presentation explaining, in general, how the ground freezing process works can be found on this link to the University of Washington's web site.

btw. 91st and 92nd streets - looking SW

This image shows some of the drilled pipes that have been installed near 91st Street.


In this image you can see the top of two of the vertical pipes that have been connected to the ground freezing plant. The pipes are white, not because of the snow, but because they are now covered with frost.

One could imagine that it will take quite some time for the snow in this area to melt.

Wednesday, January 12, 2011

Blasting to Resume on 2nd Ave


Blasting is set to resume on Second Avenue, according to a notice (shown below) that was posted on the MTA's web site about a week ago.

The MTA's contractors will use a technique known as controlled blasting as they start the process to excavate the cavern that will be used for the new 72nd Street station.

Blasting will take place inside the two existing 60-foot deep access shafts that were mined by S3 Tunnel Constructors under another contract. These shafts are located just to the north of 69th and 72nd Streets.

According to the notice, the blasting will occur up to 5 times daily with each blast lasting no more than one minute.

(Click on the image above for a readable copy.)


69th Street - looking north

A number of new construction signs have now posted by the contractor on the fence line at this location.



This is a close-up shot of the small sticker on the front of the larger sign shown above.

The letters "SSK" stand for SSK Constructors Joint Venture (JV) - the winning bidder for the contract. The letters SSK in the name stands for the three companies that make up the JV: Schiavone Construction, J.F. Shea Construction, and Kiewit Infrastructure Corp.

69th Street, SW corner - looking NE

A street level view of the work site between 69th and 70th Streets.

If you look closely at the large Liebherr crawler crane in the image above, you can see that they have installed more than 100 tons of additional counterweights on the rear of the crane. This would suggest that they intend to do some very heavy lifting with this machine.


Here's a close-up shot of the counterweights.

btw. 72nd & 73rd streets - looking SW

This is a partial view of the steel decking that was covering the access shaft hole at this location when I walked by the location on a Sunday.

This decking, I believe, is placed over the hole when the work site is not active so that nothing falls into the shaft by accident.

71st Street - looking S

Newly installed ducts and pipes.

One could assume that this is only a temporary installation, for the duration of the construction. If they were for utilities, they would probably be buried deeper under the road surface.

83rd Street - looking N

This poster, which was in the window of Tony's DiNapoli Restaurant at 1606 Second Avenue, announces that their restaurant at this location has been closed.

The location, which was taken by the MTA using an eminent domain procedure, will eventually become entrance No. 1 for the new 86th Street station.


92nd Street, SE corner - looking E

This image shows a gray wall that has recently been setup in front of the ground freezing plant on 92nd Street.

Note the orange windsock above the trailer that is behind the wall. The windsock allows people in the area to immediately determine the direction of the wind in the unlikely event that there is an ammonia leak once the plant becomes active. (If you're interested in this topic, I would recommend this excellent on-line presentation - "Ammonia Awareness and Safety".)

301 East 92nd Street

The entrance door to this apartment building has recently been replaced with a piece of plywood. Why this was done is not clear to me at this time.

Longtime followers of this project will recall that this particular building, on the NE corner of 92nd Street and Second Avenue, was evacuated by the Department of Buildings on 6/29/09. At that time the DOB had determined that the building was in danger of collapse. The building remains vacant to this day.

96th Street - looking N

A view of a portion of the active construction site just north of 96th Street. When I walked by the location last Sunday ConEd was on-site.


A close-up shot of a mechanically operated shutoff valve on a new section of gas main. The valve can be operated by turning the square nut that is shown in the image just below the label, with a special socket wrench.

97th Street, SW corner - looking W

A current view of the location where Ancillary Building No. 2 for the 96th Street station will be built. The mostly clear work site would suggest that the soil remediation work is probably now complete at this location.

97th Street - looking N

A simple view of the temporary pedestrian path at the north end of the work site.


MTA Capital Construction has recently redesigned the "Construction Look Ahead" web page for this project, as shown above. (Click on the image for a direct link to the current page on the MTA's web site.)

The new layout allows the readers to quickly locate the section of Second Avenue that is of immediate interest.


"Unused 63rd St subway tunnel, NYC"
Photo by Steve Duncan on

Most people don't realize it, but some of the tunnels that will be used for Phase I of the Second Avenue subway were built back in the 70s and 80s, and have never been used for revenue service.

The tunnel shown in this image connects the tracks on the north side of the existing 63rd Street / Lexington Avenue station with the 57th Street / 7th Avenue station.

For further information about this tunnel, follow this link to Joseph Brennan's web site Abandon Stations.


The MTA announced on their web site that the opening of the bids for the 86th Street Station Cavern Mining contract (referenced as Solicitation C-26008 by the MTA) has been pushed back to 2/4/11.

The bids for this contract were previously scheduled to be opened on 12/21/10.


Reported Location of the
Tunnel Boring Machine:
near 71st Street
as of Friday, December 31st

TBM Run No. 1 (west tunnel)
92nd Street to 65th Street
7,200 linear feet
40 foot starter tunnel
5,663 feet mined w/TBM to date
1,497 feet to run

December TBM Mining Data:
Distance mined: 1,337 linear feet
TBM mining days: 23
Avg. distance per day: 58 feet

The MTA's Construction Look Ahead web page (as of 1/11/11) says that the TBM is currently between 68th and 69 streets.

Sources tell me that the contractor (S3 Tunnel Constructors) expects to reach the planned end-point of TBM Run No. 1 (the west tunnel), at 65th Street, in about 10 days. (The remaining section of the west tunnel, from 65th Street to the bellmouth at 63rd Street will be mined using traditional methods. i.e. explosives.)

When the TBM reaches 65th Street they will start backing up the machine, all the way to the launch box at 92nd Street. Once the TBM is back in the launch box it will be jacked over the east side of the launch box and then they will commence mining TBM Run No. 2 (the east tunnel).


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

Governance Assessment of MTA Capital Program Mega Projects
Office of the MTA Inspector General

"Miracle On Second Avenue As MTA, Businesses Break Bread" (1:59)
By John Mancini
NY1 - 12/20/10

"Tony's Di Napoli Shuttered by Second Avenue Subway"
By Amy Zimmer
DNAinfo - 1/5/11

"Straphangers Mixed on Second Avenue Line"
By Matt Draper
OurTown - 1/5/11

under Notices & Posters

"in a frenzy searching for something"
By Gregory Roach
A nice writeup, with pictures, about the Total Stations that are being used on the project.


December 2010 Blizzard Timelapse
By Michael Black

For those of you who may not have received enough snow last night... check out this 38 second time-lapse video of the December 2010 blizzard.

Yes, I know that this has nothing at all to do with the Second Avenue subway. I just think this is a great little video.