North Bank Bridge Discussion (Tower A)

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Re: North Bank Bridge Discussion (Tower A)

Postby MBTA3247 » Thu Jan 22, 2015 4:10 pm

Without demolishing the building, the best you could do is add in some fairly short Tracks 11 and 12. The switch for those would have to be just beyond the end of the platform on Track 10, and probably require removing the last few hundred feet of that platform to provide the needed clearance.

As far as adding a new bridge, building one on the downstream side of the current bridges makes absolutely no sense. Tower A and Boston Sand & Gravel block the approach from the north, and on the south side you would need to realign every track. The only logical place to build a new bridge is on the upstream side, where the foundations of the old 3rd and 4th bridges are still visible. There's plenty of room there to realign the duck boat ramp to provide the space for two more approach tracks.
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Re: North Bank Bridge Discussion (Tower A)

Postby Arlington » Thu Jan 22, 2015 4:18 pm

MBTA3247 wrote:As far as adding a new bridge, building one on the downstream side of the current bridges makes absolutely no sense. Tower A and Boston Sand & Gravel block the approach from the north, and on the south side you would need to realign every track.

Well, acquiring and demolishing Spaulding isn't going to come cheap, while Tower A is already fully-owned and will practically fall down on its own. Building a bridge downstream & realigning tracks might be cheaper mightn't it?
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Re: North Bank Bridge Discussion (Tower A)

Postby F-line to Dudley via Park » Thu Jan 22, 2015 4:51 pm

Arlington wrote:
MBTA3247 wrote:As far as adding a new bridge, building one on the downstream side of the current bridges makes absolutely no sense. Tower A and Boston Sand & Gravel block the approach from the north, and on the south side you would need to realign every track.

Well, acquiring and demolishing Spaulding isn't going to come cheap, while Tower A is already fully-owned and will practically fall down on its own. Building a bridge downstream & realigning tracks might be cheaper mightn't it?


No, it really wouldn't. You've got too many highway pilings to contend with on that side and the Charles doesn't have the robust set of retaining walls downstream of Draws 1 & 2 that it has upstream. And the cost of doing the pilings tips the expense scales even further vs. dropping new decks on the perfectly usable ex- Draw 3 pilings upstream. You also can't tie it in tangently to +2 of the 8 tracks that fan out on the Somerville side. There'd be a pretty sharp S-curve tightly weaving around BS&G to get to a downstream expansion span, one that would induce more speed restrictions because the adjacent existing draw would also have to be S-curved to redistribute the tracks. It could be done, but it's fugly and doesn't have nearly the capacity or performance gains as putting Draw 3 back on its old upstream alignment.

Spaulding-as-MGH-records-storage is fungible property. That's really not going to be much of a factor, as MGH is not being picky on space or picky on proximity to its main campus. They're taking Spaulding in as-is condition and not really sinking any renovation money into the building. That's the type of thing that could get relocated anywhere for short money. And there is plenty of "anywhere" to be had in the same general area with open undeveloped parking lots right across Nashua St., Northpoint, more barren Charlestown lots ripe for redevelopment along to-be-downsized Rutherford Ave. and in Sullivan, Assembly Sq., the Innerbelt, and some brutalist West End urban renewal eyesores much closer to the hospital campus ripe for a do-over.

This isn't a real brain-teaser. Spaulding is expendable, the Duck Boat inlet is relocatable, and the Draw 3 & 4 pilings and tie-in alignments are recyclable and not impeded by Leverett Connector pilings.
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Re: North Bank Bridge Discussion (Tower A)

Postby BostonUrbEx » Thu Jan 22, 2015 5:23 pm

F-line to Dudley via Park wrote:and the Draw 3 & 4 pilings and tie-in alignments are recyclable and not impeded by Leverett Connector pilings.


What about the pedestrian bridge? I don't think acquisition and demolition of Spaulding is a major issue. But how do you justify the fact that you screwed up the new pedestrian bridge and now have to reconstruct it so you can add a new rail bridge span?
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Re: North Bank Bridge Discussion (Tower A)

Postby The EGE » Thu Jan 22, 2015 5:33 pm

There's sufficient space for at least one track and probably two without impinging on the bridge as built.
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Re: North Bank Bridge Discussion (Tower A)

Postby Arlington » Thu Jan 22, 2015 11:29 pm

The EGE wrote:There's sufficient space for at least one track and probably two without impinging on the bridge as built.

That's my sense on the upstream side. that you get 1 or at most 2 tracks before you hit the fence, ped path, bridge supports (US 1 and bike bridge) and Duck ditch. But if you did squeeze into the existing cleared land, you're best aligned with what we might call draw #2.5 (snuggled against #2 on new pilings), not the old #3.

If you really are going to re-use the pilings for old #3 and #4, they seem pretty far upstream from #2 and #1. So far upstream that you'd be pretty much be forced to fully take the Duck ramp (fill it in) so that you could diverge around some pretty serious bridge supports (which today divide the Duck ramp from the cleared rail ROW)
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Re: North Bank Bridge Discussion (Tower A)

Postby F-line to Dudley via Park » Fri Jan 23, 2015 6:34 am

Arlington wrote:
The EGE wrote:There's sufficient space for at least one track and probably two without impinging on the bridge as built.

That's my sense on the upstream side. that you get 1 or at most 2 tracks before you hit the fence, ped path, bridge supports (US 1 and bike bridge) and Duck ditch. But if you did squeeze into the existing cleared land, you're best aligned with what we might call draw #2.5 (snuggled against #2 on new pilings), not the old #3.

If you really are going to re-use the pilings for old #3 and #4, they seem pretty far upstream from #2 and #1. So far upstream that you'd be pretty much be forced to fully take the Duck ramp (fill it in) so that you could diverge around some pretty serious bridge supports (which today divide the Duck ramp from the cleared rail ROW)


The Duck ramp is negligible concern. All the reshaping around North Point Park provides adequate space for a new ramp either by the new canal they dug or further back towards Museum Way. It's been relocated several times before.


Bottom line is you've still got an easier and cheaper time of it using the old Draw 3 supports and merging under the bridge abutments than you have going downstream and shivving in sharp S-curves that are much more limited in speed and how many tracks on the Somerville side you have to cross over to get down there. If the existing tracks have to be S-curved a couple feet closer to the bridge abutments nearest Tower A to fit the Draw 3 leads that's a much gentler weave that would fit 6 tracks under the bridges, and much easier for sorting traffic on the Somerville leads. Assuming you even need to shift anything...those bridge abutments look like they could fit +2 tangent tracks snugly underneath.

I think it's fair to say all four draws will never be needed again because the N-S Link is the only above-and-beyond future advancement that would give the northside that extreme a service boost. So 3 draws and 6 lead tracks for the surface terminal is probably going to be it for serving permanent demand. And everything seems to be adequately provisioned for that except for the trivial relocation of the Duck ramp and demolishing Spaulding. I don't really see what the kvetching is about. This is pretty cut-and-dried and the new bridge structures all seem to be built with Draw 3 in mind. Keep it simple; there's no need to get all cutesy with the would-be design.
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Re: North Bank Bridge Discussion (Tower A)

Postby Arlington » Fri Jan 23, 2015 7:53 am

But once you go upstream of the fence on the Duck ramp side, you will also have to blow up the bike bridge, since it's sine-wave trusses are very low on the Duck side
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Re: North Bank Bridge Discussion (Tower A)

Postby Red Wing » Fri Jan 23, 2015 8:51 am

If you are going to do all this construction, a new pedestrian bridge is the cheapest part of your proposals. Sorry more people go under the bridge than over the bridge. blow the bridge up build a new one and add another going to North Station on the new draw 3.
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Re: North Bank Bridge Discussion (Tower A)

Postby Arborwayfan » Fri Jan 23, 2015 9:46 am

Yes, replacing a bike bridge is a rounding error in the budget of building a new 2-track drawbridge and expanding North Station's tracks and platforms to match. It's even possible that since it's so narrow, they could build the new one first and then demolish the old one, so that there would little or no interruption in trail use. Connecting the trail to North Station would be a great idea; it would put places up by North Point Blvd etc in reasonable walking distance of the station.
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Re: North Bank Bridge Discussion (Tower A)

Postby Arlington » Fri Jan 23, 2015 10:18 am

Red Wing wrote:If you are going to do all this construction, a new pedestrian bridge is the cheapest part of your proposals. Sorry more people go under the bridge than over the bridge. blow the bridge up build a new one and add another going to North Station on the new draw 3.

Acuse me of false economies in asking "what can I get without demolition" (like 1 track on a 2-slot bridge on new pilings next to #1 or #2) but everyone else seems to be doing a whole lot of demolition (Spaulding, the duck ramp, and the bike bridge, so far) just to be able to re-use the existing piers of draws #3 and #4 that "point" to a "track 20" side of the station that's likely to get real buildings built (undecked), rather than slip past Spaulding with 1 track, nip it with 2 and point at tracks 10 through (say) 15.

Are you telling me "I" can't drive new pilings for a new #3 or #0 draw for less than the cost of a (perfectly good) bike bridge?
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Re: North Bank Bridge Discussion (Tower A)

Postby Arborwayfan » Fri Jan 23, 2015 1:08 pm

Your idea does sound reasonable when you put it like that.
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Re: North Bank Bridge Discussion (Tower A)

Postby Red Wing » Fri Jan 23, 2015 4:43 pm

Arlington wrote:Acuse me of false economies in asking "what can I get without demolition" (like 1 track on a 2-slot bridge on new pilings next to #1 or #2) but everyone else seems to be doing a whole lot of demolition (Spaulding, the duck ramp, and the bike bridge, so far) just to be able to re-use the existing piers of draws #3 and #4 that "point" to a "track 20" side of the station that's likely to get real buildings built (undecked), rather than slip past Spaulding with 1 track, nip it with 2 and point at tracks 10 through (say) 15.

Are you telling me "I" can't drive new pilings for a new #3 or #0 draw for less than the cost of a (perfectly good) bike bridge?


Yup that's what I'm saying. You go on the Tower A side and then you're dealing with the tunnel exit to 93 south from Storrow Dr. You come in from the other side you have the graded area of the parking lot Straighter approaches for longer platforms and faster speeds. You also can add in more parkland. In reality demolishing all of this would be cheaper than relocating a major entrance ramp to 93.
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Re: North Bank Bridge Discussion (Tower A)

Postby Arlington » Fri Jan 23, 2015 5:26 pm

Red Wing wrote:Yup that's what I'm saying. You go on the Tower A side and then you're dealing with the tunnel exit to 93 south from Storrow Dr. You come in from the other side you have the graded area of the parking lot Straighter approaches for longer platforms and faster speeds. You also can add in more parkland. In reality demolishing all of this would be cheaper than relocating a major entrance ramp to 93.

Maybe you are under the false impression that I think new platforms would go on the Track 1 side (which would oviously create a problem), but this is just about improving throughput at peak times by having more than 4 tracks across the Charles, and no matter where the new track capacity comes in, all new platforms must be at 11 and higher.

So, no, so far you haven't shown that a Tower A / draw #0 routing would impinge on the Storrow-I93 Ramp. Nothing about the Track1-4 platforms changes (so nothing in the neighborhood of the Storrow-I93 underpass changes.

As it is Draw #1 points roughly between Tracks 2/3 and 3/4, with Tracks 1,2,&3 fanning out downstream from draw #1. A draw #0, put tight against #1 (as tight as #1 is to #2), and approached from where Tower A is today, would simply make landfall in Boston aligned with Tracks 2&3, and offer better capacity on tracks 1 to 4 (with 5 through 10+ re-allocated to make better use of the #1 and#2 we have now). With 5 through 10 feeling less crowded, you could install platforms and tracks 11, 12, & 13 (a 30% increase in platforms to go with a 25% increase in tracks across the river.

On the upstream side, putting #3 tight against the current #2 might require new pilings, but on the Cambridge shore would be approached by a single track on the currently-cleared gravel area alongside today's tracks and today's fenceline (beyond which lie a stub path, and bridge supports and just beyond them, the Duck ramp). A new Draw #3 is a very tight fit--you'd have to demolish the current pedestrian-pier-to-nowhere, and it its place, you'd only be able to fit 1 track (and leave a slot on the draw empty) but it would let you slip by Spaulding on the existing extreme upstream track (looks like Track 10). Once tied into that existing track that just skirts by Spaulding, you could fan out to serve a couple more new tracks (maybe 11, and, say, a new shorter 12-13-14). Since Spaulding no longer operates cryotanks alongside Track 10, fanning out is easy. These would (before demolishing Spaulding) share two tracks: the one on new Draw #3 and the existing extreme track on Draw #2.

Later, when Spaulding is gone and you've taken the Duck ramp (but not the bike bridge), you could lay a second track in the empty slot on Draw #3.
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Re: North Bank Bridge Discussion (Tower A)

Postby Arlington » Fri Jan 23, 2015 6:13 pm

Historic Aerials does a pretty good job of showing that the problem with the Piers for #3 and #4 is that diverge upstream (toward MGH) from #1 and #2 and point at a whole lotta railyard that's never going to come back anyway (and point at the "heart" of Spaulding, instead of, if snugged up against #2, offering the chance to build, initially, for 1 track on a two-slot draw).
1955 Historic Aerial (last one in which #3 and #4 appear)
1969 Historic Aerial (showing Spaulding under construction)
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