Underground station layouts

guitarguynboston

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I don't think I ever knew when they buried the Green Line at North Station that the tunnel was built under the Commuter Rail tracks.

Awesome Job @The EGE
 

F-Line to Dudley

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That tunnel and storage yard was built as part of the TD Garden parking garage, way back in '95.
Yeah, in total tunneling feet the '95 provision is about 2x as long as the 2004 Haymarket connector and Science Park incline completion links.
 

devnull

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Regarding that tunnel, I always thought it was a shame that trains have to slow down so much for the curves. Given it's so new relative to the rest of the green line tunnels, could they have designed it differently so trains could keep up speed? (Or were there already obstacles in the way when they were building the tunnel?)

Also, it seems wasteful that outbound trains from north station to science park usually come to a stop along the curve too (although maybe that could be something we could improve with signal improvements?)
 

F-Line to Dudley

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Regarding that tunnel, I always thought it was a shame that trains have to slow down so much for the curves. Given it's so new relative to the rest of the green line tunnels, could they have designed it differently so trains could keep up speed? (Or were there already obstacles in the way when they were building the tunnel?)

Also, it seems wasteful that outbound trains from north station to science park usually come to a stop along the curve too (although maybe that could be something we could improve with signal improvements?)
It's because the Old Garden + another tall building next door that used to be scrunched across the corner of Beverly were still standing when the New Garden was built. They didn't have any means of curve-easing around the incumbent structures, so when New Garden was built the basement had to bake the tight curve in.

Now...on the stopwatch the new alignment is still a lot faster than the old Causeway St. El. The El used to have three curves: two 90-degree street-contoured turns (Canal @ Causeway and Causeway @ Lomasney) that were each absolutely brutal...then a medium-speed S-curve (moderately curved on the leading end, very mildly curved on the back end) from Lomasney to Martha Rd. for the Science Park hookup. The new alignment entirely eliminates the sharp middle curve and mashes all the remainders into the hook under Nashua St. between the yard alignment and SP portal alignment. So on-balance what you've got now is way better and more efficient than what was there before: the first sharp curve more or less 1:1 with before because of the construction contours, the second sharp curve completely eliminated, and the S-curve into Lechmere Viaduct now consolidated into less overall invasive single-point curve.
 

Wash

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Looking at this video (linked below: skip to 30 minutes or so in for the film of the trip from Haymarket over the old El), it seems that even if North Station-Science Park is slightly slower on the new alignment, North Station/Haymarket is SIGNIFICANTLY faster.

(Also, this channel uploaded some of the best footage I've seen yet of a trip over the old Washington Street El, if that's interesting to anyone).

 

ceo

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Not to mention the rather steep portal has been eliminated too.
I believe the "new" incline to Science Park is the steepest grade on the entire MBTA system. Don't know if it's steeper than the old Canal St incline though.
 
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F-Line to Dudley

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I believe the "new" incline to Science Park is the steepest grade on the entire MBTA system. Don't know if it's steeper than the old Canal St incline though.
Comparable. Canal St. was wicked steep.
 

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