The Cambridge Tunnel

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Re: The Cambridge Tunnel

Postby 3rdrail » Tue Nov 30, 2010 11:24 am

Thank you.
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Re: The Cambridge Tunnel

Postby ThinkBoston » Tue Nov 30, 2010 11:40 pm

I appreciate the replies to the topic, and will definitely visit the Sanborn Library at some point. I've long been drawn to maps and have a penchant for research; I've spent many hours in libraries and archives.

My immediate interest in the Cambridge Tunnel is the section outbound of Kendall Station. I'm working on a proposal and it would be helpful to know the location along Main St. where the station ends and the depth of the line. Were I there in Boston, a visit to the station would allow me to make an approximation sufficient for my needs. Unfortunately, though wanting for some time to make Boston my home, I'm still stuck in Atlanta.

Knowing the Hercule Poirot like minds of those on this forum, it is revealing little to add that my inquiry has to do with the possibility of putting the Grand Junction line below street level (albeit not underground) on its run through Cambridge and much of its run through Somerville. Its rise back to ground level, to join the MBTA's commuter tracks, has more than one possible scenario.

The chief obstacle I'm aware of is the Cambridge Tunnel (the only remedy of which would be to modify the tunnel for the Red Line to go beneath a lowered rail line), though of course many other obstacles could exist. While at first the MIT building at Main and Albany, constructed over the existing track, appears to be a foreboding impediment, the lowering of the rail right of way should be attractive to the school, providing it with more options in the use of that building and making more viable other projects where they may wish to straddle the rail pathway. I know MIT owns a small portion of the Grand Junction corridor, and it likely includes the portion over which the McGovern Institute for Brain Research sits.

That the rail line has been there for a long time bodes well for this prospect, as the subterranean portion of the corridor is likely to be relatively free of the utility conduits which plague most attempts to submerge transit lines. There are only eight roadways which cross this two miles of urban rail line (capable of holding two tracks); its existence is a 'gift' which will hopefully be used wisely.
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Re: The Cambridge Tunnel

Postby MBTA3247 » Wed Dec 01, 2010 3:32 am

The Cambridge Tunnel is only just below the surface. Given the amount of disruption involved, it would likely be easier to send a relocated Grand Junction branch below the Red Line, rather than digging up both routes. Of course, that would require some relatively steep grades, especially on the north end of the tunnel approaching Cambridge St.
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Re: The Cambridge Tunnel

Postby RailBus63 » Wed Dec 01, 2010 1:22 pm

3rdrail wrote:Maybe it's just what I've grown accustomed to, but I'm not sure that express tracks in Boston historically would have improved service, and may very well have hindered it. I just don't think that we have the headway to make it work, and our streets are narrower, making the subway narrower also. (or is the subway dust making me hallucinate ?)


Sadly, this is where Boston’s ‘veteran’ subway builders may have been too enamored of their own success and thought they had all the answers. The immediate success of both local and express train operation on the IRT should have been a clear signal to the El’s planners to think bigger. New York’s planners wisely recognized that express tracks were important as a cost-effective investment in future capacity as much as the need to provide a faster ride.

As for narrower streets, the C-D line already had to pass below the Washington and Tremont tunnels in downtown Boston, so it doesn’t seem unreasonable to have built the line a little lower if need be to accommodate wider tunnels and express stations at Park Street Under and Washington. The tunnels under Fort Point Channel could have also been built wider and Dorchester Avenue from Broadway to Andrew shouldn’t have been an impediment.

The main challenge would likely have been the two-track space on the Longfellow Bridge, but this could have been expanded to three tracks at the expense of one roadway lane on each side (that would have been a lot easier to get away with back in those days before widespread private automobile ownership). Harvard Square would also have been challenging, but perhaps the end of the express track(s) and turnbacks could have been located at Central.
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Re: The Cambridge Tunnel

Postby F-line to Dudley via Park » Wed Dec 01, 2010 5:59 pm

RailBus63 wrote:
3rdrail wrote:Maybe it's just what I've grown accustomed to, but I'm not sure that express tracks in Boston historically would have improved service, and may very well have hindered it. I just don't think that we have the headway to make it work, and our streets are narrower, making the subway narrower also. (or is the subway dust making me hallucinate ?)


Sadly, this is where Boston’s ‘veteran’ subway builders may have been too enamored of their own success and thought they had all the answers. The immediate success of both local and express train operation on the IRT should have been a clear signal to the El’s planners to think bigger. New York’s planners wisely recognized that express tracks were important as a cost-effective investment in future capacity as much as the need to provide a faster ride.

As for narrower streets, the C-D line already had to pass below the Washington and Tremont tunnels in downtown Boston, so it doesn’t seem unreasonable to have built the line a little lower if need be to accommodate wider tunnels and express stations at Park Street Under and Washington. The tunnels under Fort Point Channel could have also been built wider and Dorchester Avenue from Broadway to Andrew shouldn’t have been an impediment.

The main challenge would likely have been the two-track space on the Longfellow Bridge, but this could have been expanded to three tracks at the expense of one roadway lane on each side (that would have been a lot easier to get away with back in those days before widespread private automobile ownership). Harvard Square would also have been challenging, but perhaps the end of the express track(s) and turnbacks could have been located at Central.


I think the stunted growth of the original El plans dissuaded them from building express tracks. The Atlantic Ave. El allowed for multi-directional routing either through the tunnel or along the El, but because the El was never expanded to Southie or Malden or other places where downtown would've needed the additional capacity for thru-routing the Atlantic Ave. route was always surplus to a requirement. And then the ridership collapsed during the Depression when all the Ferry transfer traffic dried up and that capacity ended up being removed. Post-BERy, the whole system has been oriented to end-to-end runs, and since Arborway was shuttered there haven't even been regular short-turns on any of the 4 lines (prior to '85 the E had both Arborway- and Heath-turning cars running simultaneously all day except well off-peak).
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Re: The Cambridge Tunnel

Postby 3rdrail » Wed Dec 01, 2010 6:22 pm

That's your opinion and you make some good points. I believe that your theory works when you only compare the two systems as equals. However, when you throw in the equation dealing with variables such as headway and useage, I don't think that Boston would benefit by express tracks. At best, it might work at the peak of rush, but that's a lot of extra work for ten hours per week advantage. In Boston, what you'd have is express trains bypassing a crowded station, only to back up traffic on the local side or, you'd have people trying to beat the system using the express trains to go beyond their stop to double back in an attempt to speed things up. This also would increase the load on the express, which in this case, would be carrying passengers that it wasn't intended to carry. New York thrives on the express system as it eats up crowds. Boston really only gets crowded ten times per week. I'm more in favor of stringing together multiple "cattle cars" at rush hour or special events, even making them limiteds. Understand that when most of the subways were built, Boston did not have the residential base outside the downtown area that it has now, and in fact, the downtown area was smaller by virtue of the fact that it was covered by the Atlantic Ocean and Charles River in places where there is now concrete. Much commuting from places like Attleboro and Stoughton came in by railroad. New York's metamorphasis was not as dramatic from the early 20th Century on in this regard. Cities like Boston and San Francisco that are now medium sized cities, were at this time really "towns" or small cities at best. SF grew with the installation of the Golden Gate and Bay Bridges. Boston grew with the Callahan/Sumner Tunnels and population expansion into "the country" (places like Mattapan where my grandmother had a farm), Roslindale, West Roxbury, etc.
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Re: The Cambridge Tunnel

Postby ThinkBoston » Wed Dec 01, 2010 9:10 pm

MBTA3247 wrote:The Cambridge Tunnel is only just below the surface. Given the amount of disruption involved, it would likely be easier to send a relocated Grand Junction branch below the Red Line, rather than digging up both routes. Of course, that would require some relatively steep grades, especially on the north end of the tunnel approaching Cambridge St.


I imagined such (the depth), but thanks for confirming that. As you identified, it would require a rather steep grade for the Grand Junction line to pass under the Cambridge Tunnel, this is why I suggested the reverse action of dropping the Red Line which can have considerably greater rates of grade change. And the alteration would need be for only a short stretch of the RL, less than 1500'. It would likely be better to construct the underpass north or south of the current tunnel, if room allows. Main Street along this stretch, from Ames to Portland St., is roughly 80-90' of public right of way, considerably more than what the lines in central Boston channeled.

Being that my proposal for using the Grand Junction is to shift the Framingham Commuter Line, and with it a diversion of the Amtrak LSL, to North Station, grade changes need to be very moderate. The line is already lower upon crossing the Charles River, it would be relatively simple to drop the rest of the run through Cambridge to that level to pass beneath the few roadways it intersects and then rise it its final run along the MBTA rail corridor.
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Re: The Cambridge Tunnel

Postby Charliemta » Wed Dec 01, 2010 10:44 pm

Main Street could easily be permanantly closed between Vassar St. and Albany Street. Traffic from Main would get to Broadway via Portland St. or Galileo Way.

That would eliminate the need to altar the Red line or build a long expensive tunnel for the Grand Junction RR.
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Re: The Cambridge Tunnel

Postby RailBus63 » Thu Dec 02, 2010 1:12 pm

3rdrail wrote:Understand that when most of the subways were built, Boston did not have the residential base outside the downtown area that it has now, and in fact, the downtown area was smaller by virtue of the fact that it was covered by the Atlantic Ocean and Charles River in places where there is now concrete. Much commuting from places like Attleboro and Stoughton came in by railroad. New York's metamorphasis was not as dramatic from the early 20th Century on in this regard. Cities like Boston and San Francisco that are now medium sized cities, were at this time really "towns" or small cities at best. SF grew with the installation of the Golden Gate and Bay Bridges. Boston grew with the Callahan/Sumner Tunnels and population expansion into "the country" (places like Mattapan where my grandmother had a farm), Roslindale, West Roxbury, etc.


Neither did New York, though – there are photos of brand-new elevated extensions of the IRT running through empty areas in upper Manhattan and the Bronx. Similarly, the IRT Flushing line and the IND Queens Boulevard line were built into sparsely-populated areas. The new transit lines drove growth and the planners were ready for it by having express tracks built in advance of when they would be needed.

In terms of Boston’s growth, a similar effect played out on a smaller scale. While the Tremont Street Subway and the Main Line Elevated from Dudley to Sullivan served already-developed areas, much of the growth throughout Dorchester, Mattapan, Roslindale and West Roxbury undoubtedly occurred in the first half of the 20th century thanks to direct or connecting service to the Cambridge-Dorchester line and the elevated extension to Forest Hills.

I know that express tracks on the Red Line will never happen, but the ‘what if’s’ are fun to think about.
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Re: The Cambridge Tunnel

Postby 3rdrail » Thu Dec 02, 2010 2:28 pm

All true Mr. Railbus, however the situation that subway developers faced in both cities was not based upon areas that were not densely populated at the time but expected to grow, alone. It was a matter of scale - translating by population (real and expected) of number of persons who would be using their respective systems. In this regard, Boston's population in 1900 was 16 % of New York's. Of course this doesn't take into account a work force of commuters who lived outside the cities and commuted in during the day, but I'm guessing that this ratio remained fairly consistant with the population ratio. Here's a table indicating population size of major cities throughout the years: http://www.infoplease.com/ipa/A0922422.html

Think of any MBTA station at full Rush in 2010. Have you ever seen a vintage BERy photograph with crowds like that ?
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Re: The Cambridge Tunnel

Postby bbfen » Thu Dec 02, 2010 10:49 pm

3rdrail wrote:Boston really only gets crowded ten times per week.


Seriously. If you're going to talk about service in the central subway/core area, then get your facts in line, would you please?

Only ten times a week during the business rush hours, plus Thu/Fri/Sat nights, plus 81 days a year (Sox), plus 41 days a year (Bruins), plus 41 days a year (Celtics), plus specific national holidays, special university weekends, plus New England-based holidays, plus the tourist season, plus.......
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Re: The Cambridge Tunnel

Postby 3rdrail » Fri Dec 03, 2010 12:15 am

Don't forget Ground Hog Day.
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Re: The Cambridge Tunnel

Postby jonnhrr » Mon Dec 13, 2010 2:43 pm

I would have to agree with 3rd rail. The lines in Boston can get crowded off hours such as when there is a delay (seems to happen every time I take the Green Line :( ) but its nothing like NYC, last time I was there taking the Lex coming back to my hotel after Mass at St. Patrick's on a Sunday Morning you could hardly stand on the platform at GCT, the lines there are crowded just about anytime except maybe late at night.

Also NY at least Manhattan is a more linear arrangement, it is a longer distance from say downtown to the Bronx, so express runs make sense to cover the distances involved.

Seems like we diverged from the original intent of the thread, maybe it should split off into an express train thread.

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Re: The Cambridge Tunnel

Postby BostonUrbEx » Mon Dec 13, 2010 2:49 pm

Why is the Alewife yard triple tracked? Were there plans to lay a triple-track express system if the Lexington extension went through?
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Re: The Cambridge Tunnel

Postby F-line to Dudley via Park » Mon Dec 13, 2010 3:57 pm

BostonUrbEx wrote:Why is the Alewife yard triple tracked? Were there plans to lay a triple-track express system if the Lexington extension went through?


I don't think so, because most of past Arlington Center was going to be above ground and was to recycle many of the former 2-track berth Lexington Branch bridges. A 3-track ROW would've required land acquisition, and the stations were pretty far-spaced from each other. The Orange Line's a bit different because the planned Reading extension already had closely-spaced commuter rail stations and sheer number of stops meant expressing through Medford and Malden would've been needed at rush hour to maximize capacity.

Alewife Yard was needed regardless because there's not a single turnback or pocket track on the line north of JFK and it would've been extremely tough to maneuver disabled or out-of-service trains through 15 miles of running track without something in the middle. It's long enough and has enough crossovers to support both OOS storage and turnbacks if, for instance, they wanted to increase rush-hour capacity by short-turning some extra trains at Alewife.
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