We all know the Second Avenue Subway project will be very costly. But we didn't know that the MTA was thinking about leaving the 300-foot tunnel boring machines underground when the project is done. The NY Sun reports that abandoning the $15-20 million machines may be "more efficient and cost-effective" rather than hauling them out. Apparently there's a precedent for this: The TBMs used for the Chunnel excavation were left there (however, other U.S. cities that have used TBMs aren't sure if theirs were left underground).
MTA Capital Construction president Mysore Nagraja says whether the machine will be left in the tunnel is up to the contractor. And, to know more about subway excavation than you thought you would ever know, here's the Sun's explanation of TBMs:
The tunnel-boring machine, which drills through rock without destroying the streetscape, is the cleanest method for tunnel excavation. In the past, subway tunnels have been excavated by dynamite blasting, or a method known as "cut-and-cover," in which temporary trenches are dug into streets during construction and then covered up when the project is completed.Well, we thought it was fascinating. You can learn more about the Second Avenue Subway at the MTA's Capital Construction site.Tunnel boring machines were used to dig the 63rd Street tunnel about 30 years ago, where the F and the V lines now pass through. That machine was not abandoned underground because the tunnel was located close to the water, Mr. Nagaraja said.
In other subway news, the Daily News reports that the MTA screwed up during the August evacuations of subway trains on the Manhattan Bridge. There was a tunnel fire, and apparently dispatchers let trains continue through, in spite of the fire and smoke conditions! Also, the FDNY didn't tell the Transit Authority they were evacuating passengers, so the third rail was still on during evacuations for seven minutes. Oh, and apparently one motorman had "repeatedly radioed alerts about the fire to dispatchers as early as [10-15 minutes before the other trains hit the fire], but the dispatchers later said they didn't hear the calls."
And a man whose arm was severed when hit by a train on Monday night is still unconscious. amNew York reports that William Santiago was in the tunnel along the A/C/E line between 50th and 59th Streets for some unknown reason when a train hit him. The operator tried to brake, but Santiago was still hit. A station agent said it was gruesome and "After they took him away they were still looking for body parts."





how do cities not know if they left behind expensive and presumably large pieces of equipment? also, if left underground is it possible for them to be moved around the system in case of future projects?
The MTA are a bunch of turds. I would love to expect competence from them but I am, unfortunately, a realist.
it's pretty common for engineers to leave tunnel boring machines underground after using them. it sometimes can cost more to hault them out than to replace them.
the machines used to carve the chunnel in england/france were left underground.
Everybody out of the chunnel!
I just hope they make the stations a little larger than the old ones. I love the cavernous, column free stations in DC. They have dozens of advantages such as wider platforms and better sightlines. You can cross to the other side of the station by going over the tracks and not through some creepy tunnel under the tracks where they had to put a mirror at the corner so you can see when someone is going to jump you.
How much do you want to bet Santiago sues?
I guess if we as a nation left behind all respectability, credibility and honor in Iraq we can very well afford to leave behind a stupid boring-machine in Manhattan.
Can't we argue about tipping some more?
boring
the chunnel machines were left behind because there were two, one starting from each end and meeting in the middle. maybe the mta version just has nowhere to resurface cheaply.
fascinating
IIRC, only one of the chunnel TBMs was left behind. For the main tube, two TBMs approached from opposite directions. One of them veered off to the side, and was left there. The other drove straight on through, met the second half of the tunnel, and drove right out the other side.
From what I understand, these machines cannot drive in reverse. For the SAS, it's irrelevant, because the subway tracks and stations are going to be built directly behind the machine as it progresses. There's no place for it to go.
That said, it could be cost-effective for them to dig a bunch of tunnels through the bedrock downtown while they're down there (in anticipation of other future lines)
I can easily see how digging a huge hole in lower Manhattan, and then disassembling/removing this thing could cost $20mil.