"Yellow Line" subway:
1: Take over the Braintree Branch of the Red Line from Columbia Junction
2: Stops at Andrew, Broadway and South Station Under Under.
3: Congress Street Subway, connections to State and Haymarket(?)
4: Tunnel under the Charles River
5: Stop at Navy Yard/Spaulding Hospital
6: Tunnel under the Mystic River
7: Stop at Chelsea Under
8: More subway on to Everett and possibly Malden Center Under.
Um..okay...
I don't think existing Braintree Branch riders will be wild about their connections to the Orange, Green, and Silver lines being degraded (especially Green where you'd be inherently going from a directly-upstairs connection to all lines to a longer walk to
some of the lines). Any of them who happen to be going to, say, Cambridge, will be extra angry. (Though the worst politics of a plan of this nature might be from the people losing their one-seat ride to their life-saving treatment at MGH, because that's the kind of framing that gets politicians
motivated.) If you're talking about duplicating the Dorchester Tunnel from Columbia Junction to the vicinity of South Station you'd be baking in a massive tunneling cost plus duplicating three stations just to avoid outright service reductions (and one of those three is a massive transfer station).
Would the Congress Street Tunnel have stops other than in the vicinity of State and Haymarket? I'd suggest Post Office Square, in part because there's plenty of room there. Haymarket in particular is going to be tricky, with the confluence of the Orange and Green Line tunnels right there. The amount of space available around Canal Street is minimal between the GL tunnel, the OL tunnel, and the O'Neill Tunnel, meaning this new subway's going to have to be deeper, which makes the transfer problem worse. Not entirely sure what route you had in mind north of there, but to get to Charlestown and then Chelsea it'd be two water crossings at the going rate for those tunnels, then a choose-your-own-adventure of tunnel boring to Everett and points north.
Having presented the reflexive-NIMBY argument (though with a possibly-unrealistic lack of scandalized horror), I'll unpack this a bit.
I don't have any issue with the effort to provide rapid transit service to Charlestown, Everett, and Chelsea as such, some of which would fill the role last filled by the Charlestown Elevated. And I'll happily give credit to an idea for serving Everett that doesn't decimate service to the major bus terminal at Malden Center by branching the Orange Line south of there. The only "Crazy" that applies to that particular section of this Transit Pitch is the cost for that much tunneling. I'd argue it would require some good numbers from a properly-conducted study (of the kind that MassDOT has of late not been inclined to do without sandbagging) to justify it. Chelsea in particular would benefit significantly from a Green Line-based Urban Ring, which would be significantly cheaper, and it's likely that Everett could glom off that pretty well with better bus service feeding GL frequencies on the Ring. But while we can debate how best to serve these areas, there's definitely merit in serving them.
I have a bigger problem with the southern half of the proposal. Severing the Braintree Branch from the downtown core and Cambridge is a service reduction. Your pitch claws some of that back in terms of the downtown core and transfers to the other lines at the cost of duplicating a three-station stretch of the Dorchester Tunnel and an entire new subway down Congress that will by definition require longer transfers to at least two lines than the current transfers. (Orange would be longer at State than DTX because of where the stations are, Haymarket would have to be deeper because that's the only place there's room to shiv a tunnel.) That's still worse service than today for anyone who's not going to the immediate vicinity of State and/or Haymarket. But it's still better than the Cambridge problem, where what's now a one-seat ride turns into a forced transfer somewhere (JFK/UMass? I suppose at least it would end the mad scramble to the correct platform brought on by Malfunction Junction's bizarre design.) in exchange for a one-seat to what I assume (in the absence of studies) is a less-in-demand destination set.
As for the Congress Street Tunnel itself, I'm ambivalent. Congress Street is, of course, one of the more viable options for additional subway construction to alleviate congestion on the existing system. I'm just not sure how much this particular project would do that. It'd take anyone transferring to Braintree away from DTX (off of Orange, they'd have to go to State? Haymarket? One hopes Haymarket because at least they could be separated out from the Blue transfers at State) and away from Park (from Green, they'd have to go to Haymarket). But you'd add transfers from the DTX-Cambridge end of the current Red Line who would have to transfer somewhere (ideally JFK, probably South) so some of those gains would be lost. I do appreciate that building this would mean Baker and company couldn't keep pushing the ludicrous Congress Street alignment for the NSRL, so that I do like.
I like the idea of serving the northern communities you mentioned with better transit. That's a good goal. I don't even particularly hate the idea of doing it with a tunnel if the numbers support it and/or the costs can be kept down (cue laughter from anyone old enough to remember the Big Dig in all its expensive, disruptive glory). I don't hate the idea of a Congress Street subway. I just don't see why the Braintree Branch is part of this at all. Absent a major demand pattern I don't know about it, its forced inclusion dramatically drives up the cost (for duplicating the Dorchester Tunnel) and forces service reductions (and additional costs to partially mitigate them) on existing riders. Hell, it's Crazy Transit Pitches, why not go from Congress to somewhere that doesn't have service? Swing over to the Seaport and at least have
something other than the dead-ending Silver Line? Find a way to swing around under the Fort Point Channel to get under Washington Street and provide a proper replacement for the El? Or my particular favorite, pop up somewhere around Cabot and eat the Fairmount Line? I think that would be a better menu of options to chew over without the drawbacks of a massive disruption to an existing service pattern.
(Oh, and in full sincerity, thank you for the post. This thread's been a little too quiet lately.)
