Red-Blue Connector

[F-line to Dudley via Park]

http://farm6.static.flickr.com/5139/5469906584_1d55078d1f_o.png

Dashed lines are current track which would be eliminated. Solid blue lines are track which would be in place after the project concludes, and the dot-dash-dot-dash lines in the red box are Mass EOT's storage/crossover plans for Charles/MGH. The black boxes west of Bowdoin are for the relocated Bowdoin, roughly between Staniford and Joy Steets.

This leaves two tails for up to three 6-car trains, or up to 2 trains and a work train/equipment, with 2 of these spots at the platforms and one in the current westbound tunnel. The tunnel storage space could be left open then, so a train could be pulled off to allow for the changing of ends off the line, and then they can quickly get out and crossover into Government Center to head eastbound.

Infrastructure is here that can be utilized to our advantage, no need to go in swinging sledgehammers and bulldozing things over because it's not for revenue service.

Also, GC-State-Aquarium is 2300 feet. GC to MGH is ***3000 feet***! I plopped Bowdoin at roughly 1500-1500, compared to the current 2000-1000. I think the better location will also attract more ridership.

http://www.eot.state.ma.us/redblue/down ... 100210.pdf

Actually, the tail track configuration can't have any crossovers at Charles behind the platform because of the bridge piers for the Longfellow. The link above shows the design. The platform is going to be under the street ahead of the Red Line station. That's why the new station's lobby has such a conspicuously large space around the bend from the Charlie gates to the RL stairs. The stairways and elevators down to the BL level would be right at the wall to cover that horizontal distance under the street where the platform is. Only crossovers would be Alewife-style immediately before the platforms, the only spot possible because the dig from Bowdoin is going to be a double-tunnel with solid center wall instead of a single cut like GC-Bowdoin. The tail tracks would then peel off from the Charles wedge platform on curves in either direction: one following the MGH/hotel side of Charles Circle and terminating under the Mass Eye & Ear parking lot, the other peeling off the Charles St. side of the Circle and ending under the street about where the CVS is. The CVS-side one would have storage for 1 consist, the parking lot side one space for 2 consists back-to-back. Only way it can be done, since the last Longfellow piers supporting the Red Line el right at the station run pretty deep underground at the same level as the BL tunnel.

The upside of this is that if the line were ever extended past Charles on a right turn under Embankment Rd. or a left turn under Storrow on the turn-of-century Riverbank Subway alignment, curves making the turn in either direction would already be built. And you can see on the diagram that even though these tail tracks are single-track in each direction the tunnel walls look to be comparable to the width of the GC-Bowdoin tunnel. The 1-track layover spaces would be equipped with an operator platform and walkway to the station, so if those were ripped out in one direction for an extension you'd have the space for 2 thru tracks. I read somewhere that this engineering future-proofing was intentional, although its primary purpose is just giving personnel the walking space to squeeze comfortably around a 1-track parking spot.

[F-line to Dudley via Park]

BTW...it's depressing as hell that it's been almost a year since the last public meeting on this, and 2009 since there were any semi-regular meetings on it. This extension is @#$% law-mandated by the Big Dig transit commitments...one of the few left that hasn't been watered down to meaninglessness or taken off the table entirely. If you can't fund today, at least inform and keep the public comment going before the CLF sues again.

[BostonUrbEx]

http://www.eot.state.ma.us/redblue/downloads/DRAFT_AltAnalysisTechRpt/Alt_analysis_report_figures_20100210.pdf

Actually, the tail track configuration can't have any crossovers at Charles behind the platform because of the bridge piers for the Longfellow. The link above shows the design. The platform is going to be under the street ahead of the Red Line station. That's why the new station's lobby has such a conspicuously large space around the bend from the Charlie gates to the RL stairs. The stairways and elevators down to the BL level would be right at the wall to cover that horizontal distance under the street where the platform is. Only crossovers would be Alewife-style immediately before the platforms, the only spot possible because the dig from Bowdoin is going to be a double-tunnel with solid center wall instead of a single cut like GC-Bowdoin. The tail tracks would then peel off from the Charles wedge platform on curves in either direction: one following the MGH/hotel side of Charles Circle and terminating under the Mass Eye & Ear parking lot, the other peeling off the Charles St. side of the Circle and ending under the street about where the CVS is. The CVS-side one would have storage for 1 consist, the parking lot side one space for 2 consists back-to-back. Only way it can be done, since the last Longfellow piers supporting the Red Line el right at the station run pretty deep underground at the same level as the BL tunnel.

The upside of this is that if the line were ever extended past Charles on a right turn under Embankment Rd. or a left turn under Storrow on the turn-of-century Riverbank Subway alignment, curves making the turn in either direction would already be built. And you can see on the diagram that even though these tail tracks are single-track in each direction the tunnel walls look to be comparable to the width of the GC-Bowdoin tunnel. The 1-track layover spaces would be equipped with an operator platform and walkway to the station, so if those were ripped out in one direction for an extension you'd have the space for 2 thru tracks. I read somewhere that this engineering future-proofing was intentional, although its primary purpose is just giving personnel the walking space to squeeze comfortably around a 1-track parking spot.

Not sure if this is directed at the lines I laid out or not, since the only thing I modified in my image was the existing track infrastructure, and I didn't do anything to the crossover or Charles. I assume you're just speaking in general, or you mistook my placement of the new Bowdoin as Charles? The part on the west end is all by Mass EOT and looks good to me. I'm fine with the EOT's plan down that end.

[diburning]

More info here:

http://www.eot.state.ma.us/redblue/

[Disney Guy]

Does the Bowdoin loop put excessive wear and tear on the cars?

It could be done more quickly and I would like to see it done that way, extending the line from Bowdoin to Charles keeping the existing tracks. Then a phase 2 where Bowdoin Station is rebuilt and the loop and some curves eliminated.

When every train has to negotiate a slow zone, the slow zone does not contribute to bunching.

[F-line to Dudley via Park]

Does the Bowdoin loop put excessive wear and tear on the cars?

It could be done more quickly and I would like to see it done that way, extending the line from Bowdoin to Charles keeping the existing tracks. Then a phase 2 where Bowdoin Station is rebuilt and the loop and some curves eliminated.

When every train has to negotiate a slow zone, the slow zone does not contribute to bunching.

It does because it's a repurposed trolley loop, although speeds are so slow "wear and tear" is relative. The outdoor elements unleash a much greater pounding on Blue Line cars than track geometry ever will, so it's a negligible factor.

It's not practical from an operations standpoint to keep the curve. The outbound peel-out from the loop to the current stub-end tunnel is very tight itself and would be an excruciating slow zone. The inbound-side transition from the stub is a much straighter curve. This complicates schedule management a lot because changing ends at Charles is slower than looping (and it's impossible to loop at Charles because of the Longfellow piers), there's a significant speed imbalance inbound vs. outbound because of track geometry around Bowdoin, and that imbalance makes it cumbersome to time inbound/outbound runs through the Charles station crossovers. The curve's also impossible to straighten out with widening on its existing footprint because it abuts building foundations.

Leaving the curve and existing platform was a studied alternative during the early design process. The consensus was that while feasible it would take cruddy hacks on the schedule management front that would reveal themselves to be long-term capacity constraints should the line get extended on the other end to Lynn. The recommendation was "do it right" by re-aligning the thru tracks underneath Cambridge St. and sacrificing the Bowdoin platform to emergency exit only. It's only 100 feet of work to do the relocation, and much of it is on the footprint of the existing inbound side of the curve so it's minor construction cost and negligible surface disruption at that spot.

Can't really argue with their reasoning there. Nostalgia for Bowdoin as-it-is doesn't trump having the most efficient thru-service alignment. Not when the project cost isn't adversely affected.

[Arborwayfan]

Changing ends CAN be very fast. Here's what I saw in Santiago, Chile, last year:

Train pulls into arrival platform of the terminal.
New operator gets into the back cab and starts settling in and setting up the cab as the train pulls out onto the tail track.
New operator takes over the train and drives back into the departure platform. Old operator gets off and, I guess, walks over to his break room or around to the other platform to get the next train, depending on his schedule. Or her; lots of women operators there.

The line where I saw this runs a 2 or 3 minute headway at rush hour. The busiest line, which does the same thing at least at it's short-turn station (using a third track just outbound of the platforms) runs on a 1.5 minute headway or better at rush hour.

In a center-platform terminal, wouldn't it be even faster? Notice is that the key part is that the new operator is already unlocking the cab, hanging up his coat, I think changing the destination signs, before the previous operator has even finished, so when one cab is shut down the other cab can take over immediately. Is there something in the T's technology that makes changing ends slow? Is the time to change ends a major factor with the kind of headways the T runs? That is, would it make service slower?

[Disney Guy]

This is not a question of Bowdoin Station nostalgia.
"Do it right or don't do it at all."
How many times have you heard that?
On the other hand I say that "something is better than nothing."
Especially with funding being iffy, getting the extension done right is going to take a long time.
Just grafting the extension onto the existing tunnels means that a significant part (east of about about Hancock St.) of the designated area does not need to be touched for a phase one. And we would be up and running quickly. From the diagrams in the pdf file linked to I judge that negligible extra construction is needed by doing the project in two halves.
Two smaller political processes to get funding (phase 1 and phase 2) are a lot easier than one larger political process up front. After phase 1 is up and running, there will be more public favor to getting phase 2 done.
I could even say that the politicians are holding the whole project hostage for want of a bigger piece of pork up front.
Operationally, while waiting for phase 2 funding, some of the rush hour service, perhaps as many as every other train, could be turned back at Bowdoin using the loop should bunching occur.

[ThinkNarrow]

The cross-section views are very interesting. The existing tunnel and station are plainly designed for the track to continue out at the incline to the surface on Charles Street. Thus, the new tunnel is required to dive downward substantially before the existing Bowdoin station. It seems highly unlikely that any reasonable use of the present tunnel and station could occur during or after construction.

[F-line to Dudley via Park]

The cross-section views are very interesting. The existing tunnel and station are plainly designed for the track to continue out at the incline to the surface on Charles Street. Thus, the new tunnel is required to dive downward substantially before the existing Bowdoin station. It seems highly unlikely that any reasonable use of the present tunnel and station could occur during or after construction.

Station, no. But the stub tunnel runs almost 500 feet after the loop curves rejoin it. You can fit 4 consists on those tracks with breathing room for MOW equipment; it's not an itty bitty thing. It was also capped at the start of the incline when the portal was sealed, so the trackbed doesn't ascend into the ceiling or anything. They'd start digging down a few dozen feet ahead to get on the downward slope of Cambridge St., and on a train you'd see the old tunnel roof ascending above your head to the end until there's a sudden roof drop at the transition to the totally new portion. Wouldn't need to be any surface disruption until that very spot.

[RailBus63]

BTW...it's depressing as hell that it's been almost a year since the last public meeting on this, and 2009 since there were any semi-regular meetings on it. This extension is @#$% law-mandated by the Big Dig transit commitments...one of the few left that hasn't been watered down to meaninglessness or taken off the table entirely. If you can't fund today, at least inform and keep the public comment going before the CLF sues again.

They should inform the public with a statement to the effect of 'Look, we have no money today to build this and we aren't likely to have the money for the next decade. Sorry.' and be done with it.

[boblothrope]

Notice is that the key part is that the new operator is already unlocking the cab, hanging up his coat, I think changing the destination signs, before the previous operator has even finished, so when one cab is shut down the other cab can take over immediately. Is there something in the T's technology that makes changing ends slow? Is the time to change ends a major factor with the kind of headways the T runs? That is, would it make service slower?

It's not hard to design a stub end terminal that can turn trains quickly. Just put in a crossover that allows at least 25 mph speeds even on the diverging route, put the crossover immediately next to the non-stub end of the platform, and include tail tracks so the train doesn't have to creep up to a bumper.

The NYC subway's designers knew this 100 years ago, but the knowledge seems to have been lost. Alewife lacks the first two features. It has a 10 mph limit when crossing over (though it used to be 25 mph until the December '09 derailment), and a curve between the crossover and the platform. And some crews don't get going quickly when the bell rings (though I can't blame them *if* they were late due to congestion and missed their break time). As a result, there are big delays getting into the station at rush hour, since the terminal can't handle the attempted 5 minute headways.

Having a motorman waiting at the inbound end of the platform saves the time it takes for the crew to walk the length of the train, but it means paying one more person while running the same number of trains.

[F-line to Dudley via Park]

BTW...it's depressing as hell that it's been almost a year since the last public meeting on this, and 2009 since there were any semi-regular meetings on it. This extension is @#$% law-mandated by the Big Dig transit commitments...one of the few left that hasn't been watered down to meaninglessness or taken off the table entirely. If you can't fund today, at least inform and keep the public comment going before the CLF sues again.

They should inform the public with a statement to the effect of 'Look, we have no money today to build this and we aren't likely to have the money for the next decade. Sorry.' and be done with it.

And then duck when the Conservation Law Foundation files the lawsuit, which it has promised it will do if another Big Dig transit commitment gets punked. They can't walk away from this one...it's the law. CLF has already sued them before; they got lucky they were able to weasel out of a few commitments with lame trade-ins in the settlement. The CLF has made it clear they are not screwing around about finishing the job on the few remaining watered-down projects. If they don't have the money, they have to start dancing about keeping some sort of planning progress moving while they seek it. Like acknowledging reality that FR/NB is bankrupting every single other system improvement, including the law-mandated ones and the ones they can't operationally live without.

A great way to pour more gasoline on the agency's problems is to give Red-Blue the middle finger and get whalloped in court with a suit they're gonna have a poor time defending because of 20 years of signed legal agreements to build these projects. Poverty isn't gonna work as an excuse; they already played out all leverage they had there on the last lawsuit settlement.

[SM89]

How about they build a tunnel connecting State and Downtown Crossing. Wouldn't that solve the issue without costing a fortune? Sure it would be an expensive tunnel, but it wouldn't cost hundreds of millions of dollars.

[Bramdeisroberts]

How about they build a tunnel connecting State and Downtown Crossing. Wouldn't that solve the issue without costing a fortune? Sure it would be an expensive tunnel, but it wouldn't cost hundreds of millions of dollars.

Since the loading gauge is damn near the same, if you were going to do that you might as well merge the Blue Line into the Orange Line. An added benefit is that you could now use the pantograph-equipped BL trains on an extension out to Needham, or have them continue straight along the Pike and run to Riverside via Yawkey.