Green Line Extension to Medford & Union Sq

ceo

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You have to have an open connection to the RR network to get that rail it delivered.
I was assuming they'd run the rail train up the northbound Lowell Line track and drag the rails off to the GLX side.
Rapid transit is organized such that they can make more hay being able to change out several 60-foot segments per night, while RR it's a considerably rarer task but one they get done with a tactical nuclear strike's worth of manpower and machinery.
They're welding the segments together anyway (or so it sounds like), and I assume replacement involves cutting out the old segment and welding in a new one. Can you not do that with CWR?
 

F-Line to Dudley

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I was assuming they'd run the rail train up the northbound Lowell Line track and drag the rails off to the GLX side.
They can do that now, but not after the line opens. Therefore they have to go with lengths serviceable by delivery from Riverside-via-subway if they want this stuff to be straightforwardly maintainable. Rapid Transit Div. orders rail in-bulk at a common-denominator length for all 4 lines, so it's better for pricing and maint consistency to stick with that standard instead of using the Lowell Line one time only during the construction phase to drop long lengths they won't ever be able to get in there again after the fence and catenary poles go up.

They're welding the segments together anyway (or so it sounds like), and I assume replacement involves cutting out the old segment and welding in a new one. Can you not do that with CWR?
What they're using is CWR; you just gave the basic definition of what it is and how it differs from jointed rail. They just have to use shorter segments of CWR and do more welds for rapid transit, since transporting the several-football-fields length ribbon that commuter rail uses is impractical on the subway. As-needed spot replacement (like a tight curve, which wears out faster than any other rail) does involve cutting what was originally a much longer ribbon and splicing in a new piece. However, while it's CWR all the same a ribbon that was spliced is less long-lasting than a ribbon that was joined end-to-end with another ribbon, since the welding job on a splice is messier. Cycled replacements will thus redo the whole original length because too many ad hoc splices on a ribbon will eventually turn up defects after a lot of wear. And that's where it's critical to go with whole lengths that can be transported through the subway instead of splicing to infinity on a one-and-done original Lowell Line delivery of the long stuff.

Cycled replacements happen way more often on rapid transit vs. commuter rail because of the sheer traffic density. However, for the reasons noted they can't transport super-long ribbons through the subway...so they're doing the short segments that can be replaced in-kind by default lengths transportable through the subway when that next cycled replacement comes after ~2 decades of daily wear.
 

JeffDowntown

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^^^^ So great to see real construction progress along the route! Thank you for the great photo set FitchburgLine!
 

Coyote137

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The chair of the control board gave the project manager and contractors a bit of a dressing down at the meeting yesterday. Nothing that would really make headlines, but still fairly strong when coming from a relatively mild-mannered guy like Aiello.
 

FitchburgLine

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The delay seems to be pretty manageable- comes from a combination of design not moving as quickly as predicted and the need to put the drainage line in before moving the CR tracks. Contaminated soil is everywhere -> that got delayed -> problems with the critical path. But the parts that aren't chained behind drainage work are either ahead of schedule or barely behind (Lechmere viaduct, Union Sq, VMF). They'll probably manage to recover once construction moves to the other side of the RoW.
 

bigpicture7

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Sorry if this is a stupid question or has already been recently addressed (it's just impossible to keep up with everything)...

Does anyone know if repair/restoration to the old parts of the Lechmere viaduct are part of this project, or entirely separate?
 

FitchburgLine

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Sorry if this is a stupid question or has already been recently addressed (it's just impossible to keep up with everything)...

Does anyone know if repair/restoration to the old parts of the Lechmere viaduct are part of this project, or entirely separate?
Separate, but the T is racing to finish design for them so they happen during the already-necessary viaduct shutdown for GLX.
 

Arlington

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Sorry if this is a stupid question or has already been recently addressed (it's just impossible to keep up with everything)...

Does anyone know if repair/restoration to the old parts of the Lechmere viaduct are part of this project, or entirely separate?
It is not entirely separate.

Definitely part of GLX: The steel "El" part of the viaduct is getting torn down and replaced (hopefully during some kind of sprint at the end where they cut the connection to the current Lechmere station and build about 500' of new concrete "El" in a hurry).

Not sure if it is GLX or GLT*: The concrete part of the viaduct across the Charles River Dam needs to be re-enforced to be able to carry 4-car trains moving at speed in both directions. Regardless of which budget (GLX or GLT) the goal is to have it done by late 2021 when the GLX opens.

* Green Line Transformation: changes in track, tunnels, bridges, and signals being made over the next decade so to permit faster, closer operation of longer "industry standard" light rail vehicles.
 

bigpicture7

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It is not entirely separate.

Definitely part of GLX: The steel "El" part of the viaduct is getting torn down and replaced (hopefully during some kind of sprint at the end where they cut the connection to the current Lechmere station and build about 500' of new concrete "El" in a hurry).

Not sure if it is GLX or GLT*: The concrete part of the viaduct across the Charles River Dam needs to be re-enforced to be able to carry 4-car trains moving at speed in both directions.

Green Line Transformation: changes in track, tunnels, bridges, and signals being made over the next decade so to permit faster, closer operation of longer "industry standard" light rail vehicles.
Thanks; appreciate the distinction you outline between GLX & GLT components.

Nothing would steal the thunder of a GLX grand opening like a long-term bustitution gap between two disconnected segments.

I appreciate the need to upgrade the concrete portion of the existing viaduct (and, aesthetically, certainly hope for its historic preservation)...but I just hope that doesn't turn into a long/drawn-out ordeal that makes a GLX commute into downtown a sucky experience.
 

Arlington

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but I just hope that doesn't turn into a long/drawn-out ordeal that makes a GLX commute into downtown a sucky experience.
Not that it is much consolation, but early on it wasn't even clear that MassDOT could take possession of New Lechmere while at the same time continuing to use Current Lechmere, which would've necessitated 2+ years of bustitution.


The land swap deal between MassDOT and PanAm (which was a big package of stuff about 6+(?) years ago) was described in such a way that it was possibly the case that they'd have to close Current Lechmere and turn it over to PanAm before they could turn their first shovel on the New Lechmere site. Apparently they worked it out (maybe they're technically renting Current Lechmere back from its new land owners?)
 

bigpicture7

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^ lots of nuance, thanks.

Well, I'm optimistic...but 2021 seems awful sporty, at this point, for finishing the not-yet-started restoration of the old concrete portion of the viaduct.
 

ant8904

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I remember they announced they need to shut down the Viaduct years ago. Why haven't they finished the design back then and have the timing prepared already rather than rushing to finish the design now?

They knew it back then, there was even a panic back then at the first announcement. MBTA already have enough bad PR in the past year alone without putting a rain on the Grand Opening of GLX because you have to bus between Lechmere and North Station (for the 3rd or 4th time).
 

stefal

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Back in mid-July they had survey crews between Science Park and Lechmere, for what it's worth...
 

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