Saturday, November 1, 2008

November 1, 2008

Source: Second Ave. Sagas - 10/31/08
A nice looking poster, from an F train.
Clearly the MTA is optimistic about having Phase I of the Second Avenue Subway running by 2015.

93rd St, NW corner
At this location there is a crew working to clear an obstruction at the bottom of one of the new holes for the slurry wall. The obstruction is probably a large rock, or section of Manhattan bedrock, that wasn't detected when the test bores were drilled before the project got started.

In this image, and the series that follow, a crew of men is using one of the big Liebherr crawler cranes to "work on" the rock down in the hole.

The crane is used to lower (and lift) a gravity-powered steel drop chisel in the hole -- the goal being to break up the rock at the bottom and create a flat surface so that the rotary drilling rig can be brought in to drill out the rock. (the rotary drill requires a flat surface for drilling through rock, otherwise the teeth at the end of the drill just break off, I was told, by a friend of The Launch Box.)

Here's a close up image of the chisel.
In this image the chisel, which slides up and down on a sort of guide, is about to be lifted out of the hole.

The chisel, which I'm told ways 15,000 pounds, has just been lifted off of the guide (which is the piece of steel that is sticking up out of the hole.)

And it's being laid down on the ground here.
(Note the beveled edge on the left end.)

Now a team of workers is connecting two sets of steel cables so that the guide for the chisel can be repositioned in the hole. (Yes, each crew member is wearing a personal floatation device. They must wear these for safety reasons, because of the slurry mixture down in the hole.)

Here the crew takes care to see that the cables don't become tangled.

The crawler crane has now taken up the slack in the cable and the men, with the help of a backhoe, work to reposition the steel guide for the chisel.

92nd, SW corner - looking E
Sections of concrete road decking have been piled at this location on 2nd Avenue.

Another view of the same stack of concrete decking.

91st, btw. 2nd and 3rd
The Second Avenue Business Association hosted a block party in the afternoon to raise awareness of its Save Our Stores Campaign.

New York State Assembly Members Micah Kellner and Jonathan Bing joined the party to show their support for the business association, and to assist with the judging of the costume contest.

- - -

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

Under Community Board 8
Second Avenue Subway Task force:

Copies of the 2 presentations that were made at
the October 28th meeting:
Construction Progress Update - 10/28/08
(Launch Box and Shaft Site work btw. 69th and 72nd Streets) - 4.8 MB

Architectural Finishes and Design - 10/29/08
(96th, 86th and 72nd Street Stations) - 6.2 MB

And this additional presentation from the August 28th CB8 meeting:
69th Street Entrance Plan with Dimension - 08/28/08

Under Web Links:
"Second Avenue Subway: Rethink 1" and
"Second Avenue Subway: Rethink 2"
from the blog The Transport Politic

I've also added a glossary, since the blog from time to time includes words and terms that may not be well known.
- I-beam
- Rebar
- Secant wall (loads slowly)
- Slurry wall
- Tunnel Boring Machine
(I'll add more over time.)

And take note that the MTA's "3 Week Looks Ahead" web page now includes a new section that details the construction activity between 69th and 73rd streets, on Second Avenue.

- - -

Sometime last week The Launch Box blog had it's 10,000th visitor. To mark this small milestone I've decided to publish a summary of the visitor statistics.

As of November 1, 2008:

Total Visits - 10,180
New Visitors - 4,874
Returning Visitors - 5,306

Total Pageviews - 23,394
Average Pageviews - 2.30 / visit
Average Time on Site - 02:34 / per visit

Traffic Sources:
Number of Sources and mediums - 160
24.84% Direct Traffic
44.02% Referring Sites
31.14% Search Engines

Top 5 Sources -
Direct / (none) - 2,529 visits
Google / organic - 1,763
en.Wikipedia / referral - 1,228
Google / cpc - 1,220 / referral - 484

Visitor Location:
92.2% United States
7.8% outside the United States

Of those from inside the United States -
65.05% New York State
4.90% California
4.66% New Jersey
4.19% Connecticut
21.20% all other States, except Montana, Wyoming or Nebraska.

The source of this data is Google Analytics.


Anonymous said...

Any idea why they use secant walls south of 93rd street, and slury walls to the north?

ffm784 said...

I've been told (by a friend of The Launch Box) that they use slurry walls in some areas, and secant walls in others, because of the water content of the soil in those areas.

Slurry walls are usually used in areas that are higher in water content, i.e. there might be underground springs in that area. (Apparently, it is soggier soil closer to 94th Street, than it is closer to 91st Street (where the secant walls begin).

Secant walls are used where the soil is drier.

Anonymous said...

The product being used as part of the tunnel boring in front of our building is called InstaFreeze (KB MSDS). Here's a link to the company website. Any idea if this is toxic? Our buildings water is brown as are other people's who are in my area (94th Street and 2nd). We cook with the water, our dogs walk through it and we all shower in it. Is it safe? It seems to me that the inspectors that were present at the beginning of the project have disappeared as have the DEP cars. We are worried...any comments would be appreciatedl

ffm784 said...

I don't have the answer to this question.

I would suggest that you contact Claudia Wilson at (212)792-9716 to discuss this concern. (Claudia is the MTA's Community Liason for this project.)