Green Line Extension to Medford & Union Sq

stefal said:
The middle OCS poles are provisioned for Commuter Rail Electrification, correct? Is that retaining wall on the commuter rail side on the extreme edge of the ROW? It seems like there's no space for overhead catenary poles to fit.
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Correct on center pole provisioning (where there are center poles they allow the side walls to nestle in closer)

elsewhere I think we get poles on the outside or even hung fro the walls own H beams
 
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On the 2 top pics of the new viaduct, What is that little square thingy up there? Is it an elevator shaft? Is there a new station being put there? :)
 
Oh, so this time, the new Lechmere station will be elevated up higher off the ground, hey?!! Cool!! :)
 
I would think that if that was intentional there would be some kind of trellis or other surface treatment to encourage the vines to grow up the wall. Otherwise it's certainly a brilliant solution. Too bad they can't get the vines to grow on railcars :)
 
BostonTrainGuy said:
I would think that if that was intentional there would be some kind of trellis or other surface treatment to encourage the vines to grow up the wall. Otherwise it's certainly a brilliant solution. Too bad they can't get the vines to grow on railcars :)
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Yeah, I'm not sure if the stuff (ivy?) was intentional or not on the SE XWay, but it looks good and it seems to not protrude much, which is a prime consideration in GLX's tight spaces.
 
Javier said:
How long they last?
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Complicated. It's hugely variable depending on hyper-local climate & moisture conditions on an individual stretch of track. 8-10 years on the shortest end, 20-25 years on the higher end of average. And lots of asterisks for exceptionally long-lived cases. Automated inspection equipment can detect when one is too compromised, and then the tie gets a spraypaint mark for replacement. However, because the lifespan is so hugely variable, cycled tie replacements usually only target 1 out of every X ties at a time (plus any adjacents with flunked-inspection spraypaint marks) and make repeat visits to a given area several times before all ties in the area get replaced.

New England has a low incidence of concrete ties because their failure mode (spalling around the tie clip area) is singularly vulnerable to getting prematurely exploited by the nightly freeze-thaw cycles here. Less wood, more composites get used elsewhere where it either doesn't freeze or (like Upper Midwest) where it stays mostly below freezing all winter instead of cycling every 24 hours.
 
Does anyone have a pdf copy of this
Appendix B – Station and Alignment Selection Analysis, Prepared by Vanasse Hangen Brustlin, Inc., October 2009.
from the glx section 4(f) evaluation/draft environmental impact statement
 
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