I-90 Interchange Improvement Project & West Station | Allston

Tallguy

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At the probable timescale of this project, even the Commonwealth should be able to build the Readville maintenance facility and cut a deal with CSX.
 

stick n move

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Wouldnt the elevated gjrr block the street grid from crossing over the pike and west station? Thats probably why that option hasnt been proposed.
 

BostonTrainGuy

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Wouldnt the elevated gjrr block the street grid from crossing over the pike and west station? Thats probably why that option hasnt been proposed.
Going back through the thread and looking at the maps and renderings it looks like there are no streets passing over the tracks east of West Station which is where the tracks would have to come down to ground level.

BTW - If you go back to the beginning you can see that the original plans were very different from what we have now.
 

Charlie_mta

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I think the operational question is whether there is enough room between West Station and the Throat to get the Grand Junction up to the required viaduct elevation, given RR grade constraints. Note in the proposals the Worcester Line is also somewhat elevated at the Throat, so that increases the elevation needed for Grand Junction even more.
On Google Earth I'm measuring 1,400 feet from the east end of the West Station platforms to the start of my proposed GJ viaduct, with allowance for room for the Worcester line to curve under the proposed viaduct. At 1.5% GJ RR grade, that provides a rise of 21 feet. If the grade could be 2%, then the vertical rise in the 1,400 feet would be 28 feet. I'm not sure what the maximum grade on a railroad can be. Of course if the Worcester Line is not raised up at the throat as shown in the typical section in Stefal's post above, then that would help.
 

Charlie_mta

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Also I'm thinking the West Station platforms for the GJ (if passenger service runs on it in the future) could be a few feet higher than the platforms for the Worcester branch, thus providing a bit more room for the ramp up to the GJ viaduct I'm proposing.
 

Charlie_mta

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MassDOT's current at-grade proposal (from stefal)"

My modified at-grade proposal with the GJ stacked over the Worcester Line:


The savings in shoreline fill is about 21 feet hoizontal distance. not 25 feet, due to space needed for columns for the RR viaduct. Still, the RR viaduct avoids having to fill into the Charles River for the roadways. An off-shore walkway as shown would still be needed.
 

BostonTrainGuy

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You sold me, Charlie. But make it a nice boardwalk from the shore instead of that stiltway in the river.
 

reno

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On Google Earth I'm measuring 1,400 feet from the east end of the West Station platforms to the start of my proposed GJ viaduct, with allowance for room for the Worcester line to curve under the proposed viaduct. At 1.5% GJ RR grade, that provides a rise of 21 feet. If the grade could be 2%, then the vertical rise in the 1,400 feet would be 28 feet. I'm not sure what the maximum grade on a railroad can be. Of course if the Worcester Line is not raised up at the throat as shown in the typical section in Stefal's post above, then that would help.
Your calculations assume the grade of the Worcester Line is flat (0%). Is it?
 

Charlie_mta

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Your calculations assume the grade of the Worcester Line is flat (0%). Is it?
I don't know. This is just a concept and a topographical survey and a 30% design would be needed to validate things.
 

F-Line to Dudley

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On Google Earth I'm measuring 1,400 feet from the east end of the West Station platforms to the start of my proposed GJ viaduct, with allowance for room for the Worcester line to curve under the proposed viaduct. At 1.5% GJ RR grade, that provides a rise of 21 feet. If the grade could be 2%, then the vertical rise in the 1,400 feet would be 28 feet. I'm not sure what the maximum grade on a railroad can be. Of course if the Worcester Line is not raised up at the throat as shown in the typical section in Stefal's post above, then that would help.
1.5% is the FRA max grade. Anything higher needs a waiver, and waivers are usually only granted in very specific cases like a fixed bridge replacing a movable bridge (all of the T's over-grade inclines were on former movable bridges). 1% is the recommended grade.

You only need to rise ~18 feet (16 for the physical structure over the roadway, up to +2 for decking/ballast) above Pike grade to overpass the highway and meet Interstate highway vertical clearances.
 

F-Line to Dudley

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Also I'm thinking the West Station platforms for the GJ (if passenger service runs on it in the future) could be a few feet higher than the platforms for the Worcester branch, thus providing a bit more room for the ramp up to the GJ viaduct I'm proposing.
They have to be at the same level because all of the West platforms are on the mainline. The tracks tie in beforehand, and there's a quick set of pick-a-platform crossovers for changing tracks...so it all has to be at the same level. Now...West itself is a godawful mess of a design that needs a ton of finishing work before it's ready for prime time. Its layout is self-alienating from its surroundings, the mission statement on the attached (and ever shrinking) storage yard is completely incoherent, the busway-on-stilts is ludicrously overcomplicated, and the platform setup is excessive for the services that would actually use it (as well as taking a giant punt on whether the GJ itself has the capacity to run the Purple Line shuttle they envision on it, because that *still* has not been studied well enough to be proven). The 'throat' saga has simply created a giant singularity time-and-resource suck that prevents any further refining work on those troubleshoots.

So unfortunately any 'throat' fix that has direct dependencies on West Station design changes ends up swimming in quicksand, because the planning process for all of Beacon Park has become completely factionalized to its constituent parts with little overall coordination. And the 'throat' has taken everything else with unanswered questions--the transit accommodations, the street grid, the resultant developable slabs--hostage the more bogged down it gets on trying to reach a final decision. It's not going to get any less bogged down by increasing its complexity with other design dependencies like West's layout/elevation. You're best off by far drawing a project limits for the Grand Junction's elevation interface at those leading crossovers, and treating the West debugging as a whole separate project area.
 
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Stlin

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1.5% is the FRA max grade. Anything higher needs a waiver, and waivers are usually only granted in very specific cases like a fixed bridge replacing a movable bridge (all of the T's over-grade inclines were on former movable bridges). 1% is the recommended grade.

You only need to rise ~18 feet (16 for the physical structure over the roadway, up to +2 for decking/ballast) above Pike grade to overpass the highway and meet Interstate highway vertical clearances.
16 ft feels low for me if we're stacking the tracks - I don't have a table in front of me, but as I recall the Worcester Main here is Plate C, 15'6" bilevel, then figure another 2-3 feet for electrification... I think you'd need about 19ft of vertical clearance, +2 for decking. That's just about perfectly 1.5% grade, which admittedly might be a touch tough coming out from a dead stop @ West.
 

BostonTrainGuy

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What's the grade of the present GJ? It looks like a pretty good grade climbing up to the bridge now.

I suppose at this point West Station could be moved a bit west to accommodate any needed running room to the viaduct.
 

F-Line to Dudley

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16 ft feels low for me if we're stacking the tracks - I don't have a table in front of me, but as I recall the Worcester Main here is Plate C, 15'6" bilevel, then figure another 2-3 feet for electrification... I think you'd need about 19ft of vertical clearance, +2 for decking. That's just about perfectly 1.5% grade, which admittedly might be a touch tough coming out from a dead stop @ West.
16 ft. is just for where the GJ has to pass over the highway for switching sides. If you're stacking the mainline...yes, absolutely you have to do it as Plate C + 2.5 ft. for 25 kV electrification, which is an 18 ft. minimum. And weight-rate the upper deck for 286,000 lb. railcars per new-construction guidelines. And have an open enough airflow design to diesel-vent the lower level properly. While you can trace a path to absolute engineering feasibility, I don't think the cost is going to be something MassDOT wants to swallow. Stacking tracks is probably not going to be an option they entertain in any way/shape/form because of the endemic cost increasers.
 

ccole

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I reached out to the project team and they responded saying that a stacked rail viaduct has been considered but the problem is that they would need a lot of runway for the grade to go up and there isn't enough space between West Station and the potential viaduct to do that and to have the necessary switches between the rail lines. Additionally, they pointed out that a rail viaduct would require much heavier infrastructure due to the rail weight and that there would be a lot of noise from the locomotives getting up to the viaduct level.
 

Charlie_mta

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I reached out to the project team and they responded saying that a stacked rail viaduct has been considered but the problem is that they would need a lot of runway for the grade to go up and there isn't enough space between West Station and the potential viaduct to do that and to have the necessary switches between the rail lines. Additionally, they pointed out that a rail viaduct would require much heavier infrastructure due to the rail weight and that there would be a lot of noise from the locomotives getting up to the viaduct level.
Those sound like reasonable issues. Thanks!
 

bigpicture7

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Those sound like reasonable issues. Thanks!
But what about splitting the difference: having the lower rail line slightly below grade and the upper rail line slightly above grade? This would create less of a climb situation for the locomotives. I know there'd be drainage/flooding concerns for the lower rail line, but we'd be talking about a much smaller footprint for the two-track bed (compared to a highway) and it would be a couple hundred feet away from the river (nonetheless mitigation approaches required, but doable?).
 

JeffDowntown

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But what about splitting the difference: having the lower rail line slightly below grade and the upper rail line slightly above grade? This would create less of a climb situation for the locomotives. I know there'd be drainage/flooding concerns for the lower rail line, but we'd be talking about a much smaller footprint for the two-track bed (compared to a highway) and it would be a couple hundred feet away from the river (nonetheless mitigation approaches required, but doable?).
River induced flooding is not the only concern. That whole area is subject to stormwater induced flooding as well. I doubt putting the Worcester Line in a trench is going to fly.
 

F-Line to Dudley

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But what about splitting the difference: having the lower rail line slightly below grade and the upper rail line slightly above grade? This would create less of a climb situation for the locomotives. I know there'd be drainage/flooding concerns for the lower rail line, but we'd be talking about a much smaller footprint for the two-track bed (compared to a highway) and it would be a couple hundred feet away from the river (nonetheless mitigation approaches required, but doable?).
If the feds are being absolutists about the flood control, I doubt flipping the modes is going to substantially redirect the meat of their complaint. The FRA can be tasked with being just as P.I.T.A. a vector as the FHA for that sticking point.

Also...when they say the viaduct has to be rated "heavier" for RR weights, it's a LOT heavier. 286,000 lbs. per car vs. 80,000 lbs. per vehicle for an Interstate highway for new-construction structures...over 3-1/2 times heavier. It'd be a slimmer width-profile viaduct, but quite possibly equal-or-higher on expense.
 

RandomWalk

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It seems to boil down to choose two:
- Grand Junction
- 8 lanes of the Pike at ground level
- Zero filling of the Charles
 

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