General Infrastructure

I completely agree. Pedestrianized canal street is begging to happen. Nice work, I'll add my voice to the survey!
 
Re: Watertown Dam

Arlington said:
I like small hydro with a good fish ladder.
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If a Watertown dam with the current elevation change were maintained, how much power would a hydroelectric generator there produce in the typical year, and how many homes in Watertown would need to have their roofs covered in solar panels to generate an equivalent amount of power?

Also, if the Watertown dam were removed and a small hydro generator installed at the Moody St dam, would that Moody St dam necessarily produce any less power than we'd get with a new Watertown dam with a hydroelectric generator plus installing a hydroelectric generator at Moody St? (That is, if removing the Watertown dam were to end up increasing the drop at Moody St, does that mean that the entire drop would get moved to the dam in Waltham, and is hydroelectric power simply proportional to elevation change times volume or mass of water flow?)

I also wonder whether dam reconstruction could involve installing more locks for recreational boats at locations like Moody St and along the Connecticut River. Maybe 100' long by 30' wide lock chambers would be a reasonable goal?
 
I have seen some general studies (not in particular to the T) on wider doors reducing dwell time - I think NYC is estimating that going from 50" -> 58" doors with reduce dwell time up to 32%. Seems loftful thinking though - especially at the bottleneck stations that you have pointed out in South Station, Park, and DTX. I also think that once everything is standardized to the new rolling stock (both Red & Orange fleets), they will probably put more permanent floor markings on platforms, as that seemed to surprisingly help when they trialed it on the Orange.
 
If the spacing from doorway center to doorway center turns out to be consistent between the 1800 series Red Line cars and the future cars, it may be sufficient to just retire the 1500/1600/1700 series cars to be able to add those markings for the Red Line (and to make the markings based upon the dimensions of the cars with the 32" door leafs). Or, if the door spacing is slightly off but only by a few inches, it might turn out that marking 64" spaces for the future cars might still allow 1800 series cars to line up well enough.
 
Joel N. Weber II said:
If the spacing from doorway center to doorway center turns out to be consistent between the 1800 series Red Line cars and the future cars, it may be sufficient to just retire the 1500/1600/1700 series cars to be able to add those markings for the Red Line (and to make the markings based upon the dimensions of the cars with the 32" door leafs). Or, if the door spacing is slightly off but only by a few inches, it might turn out that marking 64" spaces for the future cars might still allow 1800 series cars to line up well enough.
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Given that they are replacing the the entire 1800 fleet as basically an addon to the current order, I don't see why they would really need to take them into account. Mark everything out for the new cars when enough critical mass arrives, and in a year or two that will be all that is running anyways.
 
Hey- wrong thread I posted in. Is there anyway to have a mod move this over to the new Orange/Red Line Cars thread?
 
State has announced a 4-day closure of the Mass Ave over Comm Ave bridge in the Backbay this Summer to replace the bridge. Work begins in next few weeks with the closure of the westbound underpass on Comm Ave to rebuild the abutments. This is on top of a 18 day closure of Comm Ave expected this Summer to replace the Comm Ave bridge over the Mass Pike.
 
CSTH said:
Chicago is digging a 1-mile long, 18 ft. diameter concrete-lined waterproof tunnel with a TBM for ... $70M.

Its for flood control, not transit, but (/and) its an interesting datapoint in the infrastructure cost conversation.

http://www.chicagotribune.com/news/local/breaking/ct-albany-park-tunnel-htmlstory.html
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I like the sound of that price per mile, but that article does nothing to put the described project into context. As I understand TBM economics, there is a steep exponential climb as you go up the diameter scale. Well, not exponential: but steep.

The article calls the TBM "enormous", but at 18 feet diameter, it's less than a third the diameter of the "Big Bertha" machine out in Seattle. Big Bertha was the largest diameter TBM at the time it was built (and maybe still holds the record?), so I grant that I just jumped to the other end of the scale. But an 18foot diameter tube is just not that big these days compared to what's being deployed regularly in major cities not named Boston. When it rolled off the plant at Herrenknecht, it probably looked like a toy compared to their big boys. Check out their website, you really have to rummage around to find something this small:

https://www.herrenknecht.com/en/home.html

The Big Bertha TBM itself cost $80M - just the machine. The original budget was $3.4B for a 2 mile tunnel project, before it all went sideways. Some of that budget might be for removal of the old viaduct, but in any event, my point is, as you go to bigger diameters, the price really soars.

I have seen repeated assertions that TBM costs are consistently dropping and I hope it's true. But given the size of TBMs we'd need to dig the NSRL (just picking one project completely at random), I think we're still up into the $Billions.

ETA: I would be very interested to see if we could find a similar sized tunnel dug, say, twenty years ago, to compare costs. It could be that this $70M is in fact a huge decrease in tunneling costs from prior generations of machines of similar size. I would think that would bode well, relatively speaking, for the larger ones, too.
 
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How long do TBMs usually last? 80million for Big Bertha is only about 4% of the MBTA's overall budget of 2 billion. Seems like a no-brainer to pick one up and start letting it loose. If they burn out after effectively a few miles, though, it might not be such a great idea.
 
bakgwailo said:
How long do TBMs usually last? 80million for Big Bertha is only about 4% of the MBTA's overall budget of 2 billion. Seems like a no-brainer to pick one up and start letting it loose. If they burn out after effectively a few miles, though, it might not be such a great idea.
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wut.
 
CSTH said:
Chicago is digging a 1-mile long, 18 ft. diameter concrete-lined waterproof tunnel with a TBM for ... $70M.

Its for flood control, not transit, but (/and) its an interesting datapoint in the infrastructure cost conversation.

http://www.chicagotribune.com/news/local/breaking/ct-albany-park-tunnel-htmlstory.html
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We have direct experience with this type of project here via the MWRA.

North Dorchester Bay Storage Tunnel; 17 ft diameter, 2.1 miles long mostly under Day Blvd. TBM project that came in well under budget and time. Also great demonstration of TBM operation in soft glacial till and Boston blue clay.

http://www.mwra.com/03sewer/html/sewcso.htm#ndbaytunnel

It is the project no one in Boston knows about, because it caused so little disruption, and came in under budget and time schedule.

Some info on the TBM:
http://www.barlettaco.com/projects/TunnelProjects/CsoTunnel/csotunnel.html
 
fattony said:
wut.
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Just saying West referenced that the Big Birtha TBM cost $80million. That isn't really a lot of money in the grand scheme of things for the state to purchase, but it would depend on their lifetime (which I would assume is measured in miles it can dig/hours of usage). $80m isn't really a great deal if you have to replace it/overhaul it every other mile.

Basically, I am saying if they last for a while, at 80m, I would think it would be a good investment to have at the MBTA, and maybe they can actually plan real subways around it.
 
bakgwailo said:
Just saying West referenced that the Big Birtha TBM cost $80million. That isn't really a lot of money in the grand scheme of things for the state to purchase, but it would depend on their lifetime (which I would assume is measured in miles it can dig/hours of usage). $80m isn't really a great deal if you have to replace it/overhaul it every other mile.

Basically, I am saying if they last for a while, at 80m, I would think it would be a good investment to have at the MBTA, and maybe they can actually plan real subways around it.
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TBM are often specified with a life for a single tunnel bore. There is a big cost with both insertion and extraction of the machines. They are often not extracted, but just left in the ground, having bored past the end of the designated tunnel.
 
JeffDowntown said:
TBM are often specified with a life for a single tunnel bore. There is a big cost with both insertion and extraction of the machines. They are often not extracted, but just left in the ground, having bored past the end of the designated tunnel.
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Ah, well, that then answers my theory, I had thought they were reusable. I guess making them more reusable/easier to extract at the end would be a good start to changing the market for Musk. Either way we should be doing more tunneling (or even cut and covers) in general.
 
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