Green Line Extension to Medford & Union Sq

Arlington

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Looking at the rebar-pillars-wrapped-in-plastic what is your guess:
  • Have they actually situated all the vertical columns they need? or were there some intermediate columns that coincided too closely to elements of the steel el that they couldn't pre-set them?
  • Another way of asking the above: will the steel spans of the new viaduct be long enough to jump from pillar to pillar here, or will they need to "infill" some other supports?
  • What date do you think the new viaduct will look "structurally done" by?
  • (It seems like after the viaduct is structurally done there's only a few months of track-signals-power left to be done here)
 

F-Line to Dudley

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When will the poles be installed for the overhead power lines?
Last. There's going to be big poles on the center-median fence between GL & CR sides so they have consolidated infrastructure to someday hang electrification bracket arms over the CR side from the same poles. But they won't pour the supports for those until all structures are done and they don't need to move heavy trucks around on the ROW anymore to do embankments or bridge undersides. Poles (incl. the lighter weight far-side mounts) + utilities will go in after the GL tracks are already laid and tamped and they're ready to 'seal' the two modes from each other with fence install.
 

Stlin

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Last. There's going to be big poles on the center-median fence between GL & CR sides so they have consolidated infrastructure to someday hang electrification bracket arms over the CR side from the same poles.
That... sounds like the T is better at future proofing and provisioning than I gave it credit for, given that CR electrification was barely a glimmer back whenever (1990-2017) that spec was developed. I could have sworn that the 2017 contract called for twin side poles, but that's a easy, affordable and sensible change if made early enough.

This begs the question though: obviously, 13.8kV/600v is a completely different beast than Amtrak's 25kV system (which I assume the T will build to for simplicity's sake), so I doubt that any of the TPSS sites were spec'ed to be readily suitable to accept a paralleling station, for all that they seem over sized to me. It isn't hugely important, as the between Red Bridge and CR and GL VMFs, there's enough land to build something for north-side terminal electrification.
 

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That... sounds like the T is better at future proofing and provisioning than I gave it credit for, given that CR electrification was barely a glimmer back whenever (1990-2017) that spec was developed. I could have sworn that the 2017 contract called for twin side poles, but that's a easy, affordable and sensible change if made early enough.

This begs the question though: obviously, 13.8kV/600v is a completely different beast than Amtrak's 25kV system (which I assume the T will build to for simplicity's sake), so I doubt that any of the TPSS sites were spec'ed to be readily suitable to accept a paralleling station, for all that they seem over sized to me. It isn't hugely important, as the between Red Bridge and CR and GL VMFs, there's enough land to build something for north-side terminal electrification.
It's not as self-perceptive as it sounds. The clearance envelope is tight at the divider, so pole maintenance is a born P.I.T.A. If a tree comes crashing down from the embankment and tears wire down, they simply want overbuilt-for-overbuilt's sake where they have to work close to the CR clearance envelope during repairs. Plus the needs for mounting either-mode cable bundles, signal heads, etc. means some of the center poles would have to be thicker-than-norm, so why guesstimate future needs when you can mass-order one pole type for that whole side. That's the be-all of it. The fact that they can support electrification bracket arms over the CR side doesn't mean that's always the top priority. Sometimes it's going to be signal gantries that have to be hung over there instead.

Paralleling stations are a whole separate animal that isn't part of the OCS to begin with, so that's neither here nor there for the pole assemblies. Nor does any return current whatsoever go through the pole (that would be a muy bad short-out). It's all about weight rating of the crap you can hang off them, and a little bit on crashworthiness for having poles robust enough that an AMTK Philly-type horror wreck wouldn't be capable of taking down multiple poles (Green or CR sides). First paralleling station on Lowell wouldn't be until after the Community Path pulled away, so isn't a consideration to begin with for the area of maximal squeeze where they're trying to keep their center-dividing physical plant to minimal profile.
 

stick n move

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Awesome, thank you. Reading the site it says the planted wall also has the benefit of graffiti control, along with better sound deadening, looks etc. I didnt even think about the graffiti aspect, thats awesome!

I personally cant stand most graffiti that looks like a 3rd grader scribbed their name on a wall, this is a huge benefit that it prevents this. Not only is there no graffiti, but its green too, talk about best of both worlds. They should definitely use more of these.
 

JeffDowntown

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Awesome, thank you. Reading the site it says the planted wall also has the benefit of graffiti control, along with better sound deadening, looks etc. I didnt even think about the graffiti aspect, thats awesome!

I personally cant stand most graffiti that looks like a 3rd grader scribbed their name on a wall, this is a huge benefit that it prevents this. Not only is there no graffiti, but its green too, talk about best of both worlds. They should definitely use more of these.
Spring, Summer, Fall seems like a win. What will it look like in mid-winter?
 

Arlington

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... better sound deadening
The planter walls do appear to have two advantages: varied texture & angle.

The research (or sales materials?) I've seen stresses a preference for angling sound walls (tipping the top away from the noise source) so as to better reflect the sound skyward, rather than just "bounce out" the other side.

I think that angled sound walls are more important when they are only on one side. If you have vertical sound walls on both sides then you can do pretty well having the sound just "bounce back and forth" in the trench (as we apparently have chosen for most of GLX.
 

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From UHub...photo tour of the derelict Lechmere Viaduct draw span machine room, via a T employee.
 

whighlander

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From UHub...photo tour of the derelict Lechmere Viaduct draw span machine room, via a T employee.
From Mass DOT
The rest of the Viaduct where it crosses McGrath/OBrien [your choice] to be removed over the weekend with full closure of the roadway

Closure of part of Monsignor O’Brien Highway in East Cambridge

This Weekend, Staring Early Saturday, June 20

Monsignor O’Brien Highway will be closed to outbound traffic from East Street to the Gilmore Bridge and inbound from Third Street to Cambridge Street.

Green Line Extension project demolition work occurring.

BOSTON – A portion of Monsignor O’Brien Highway in East Cambridge will be closed this weekend to provide Green Line Extension (GLX) work crews adequate space to safely demolish the remaining section of the Lechmere Viaduct deck where it crosses over the Highway at Lechmere Station.

Traffic detours will go into effect before dawn on Saturday, June 20, and will remain in place throughout the weekend until early Monday morning, June 22. Demolition activities will occur from 7 a.m. to 7 p.m. followed by clean-up activities from 7 p.m. to 10 p.m. Less disruptive activities such as work zone preparation and breaking down traffic control items will take place overnight.
 

ceo

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Aren't those precast planter walls the old retaining walls?
 

George_Apley

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I was thinking that myself. It seems too overgrown to be new. I confess that I've never paid much attention to the retaining walls in the past.
 

RandomWalk

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Yes. I think the plan was to obliterate the Sycamore-Central stretch with the bike path, when it made the needless side swap in one of the earlier plans.
 

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