Amazon and New T Stuff

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Re: Amazon and New T Stuff

Postby parovoz » Mon Oct 23, 2017 10:19 pm

So, why not use the Bowdoin tracks for storage, then? I assume the existing storage area would remain accessible to the motormen?
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Re: Amazon and New T Stuff

Postby csor2010 » Mon Oct 23, 2017 11:22 pm

parovoz wrote:So, why not use the Bowdoin tracks for storage, then? I assume the existing storage area would remain accessible to the motormen?


The existing tail tracks lie in the footprint of the extension tunnel and therefore would be likely be severed. Depending on the relative depth, method of construction, and whether or not a station is retained at Bowdoin, the tunnel structure surrounding the tail tracks may also be destroyed or rendered unusable by the extension construction.

It's also unclear to me whether the Bowdoin loop and tail tracks would even remain usable during construction, or if trains would be have to be turned at Government Center. With only a single crossover at GC, only the Bowdoin-bound track would be usable for short-turns - not sure what effect this would have on throughput.

Another note on the tail tracks - when unoccupied it's possible that they would allow terminating trains to enter the station at higher speed as a signal block could exist between the end of the platform and the end of track. If the tracks stub out within the station, trains would likely have to enter at a restricted speed (e.g. prepared to stop, as they do at North/South station).
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Re: Amazon and New T Stuff

Postby F-line to Dudley via Park » Mon Oct 23, 2017 11:32 pm

parovoz wrote:So, why not use the Bowdoin tracks for storage, then? I assume the existing storage area would remain accessible to the motormen?


The Bowdoin tail tracks are the new mainline to Charles MGH. Their footprint is outright cannibalized for any permutation of the build...gone, obliterated, bye-bye. Also, the loop area and current Bowdoin station are slated in nearly all engineering permutations to be partially demolished to straighten the ROW, as Blue couldn't be dispatched effectively to Charles if it were forced to crawl at 3 MPH around two-thirds of the existing loop in order to transition onto the current-tails/future-mainline. So the storage has to be re-created away from Bowdoin, because Bowdoin is going to be a nuke zone for realignment.

You're not talking more than a couple back-to-back trainsets on each Charles tail. Maybe 1 six-car set on one tail and 2 six-car sets on the other, if they're of unequal length. It's considerably smaller than even Alewife Yard on the Red Line, because Orient Heights isn't that far away in absolute distance. But you must...full-stop...have some place to park on that end of the line for starting a shift change or storing a disablement, or the whole Blue Line doesn't function properly.
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Re: Amazon and New T Stuff

Postby CRail » Fri Oct 27, 2017 10:39 am

Each track holds 1 6 car set. AM service starts from Orient Heights only, no trains enter from Bowdoin. The stub tracks are the remnant of the Cambridge Street portal used by streetcars and later used to send East Boston Tunnel cars to Eliot shops for work before the line went west of Maverick. It's not a yard and neither track can be used without an adverse move either going into or coming out of it. Therefore, only irregular circumstances warrant its use.
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