JFK/UMass Configuration

[nick]

I was thinking over the weekend about the bizarre configuration of the JFK/UMass station, and how potentially incredible it could be.

The rapid transit portion of the station is split into two platforms, each serving a separate branch of the Red Line. This forces inbound passengers to wait in the paid fare lobby above the tracks for an announcement saying which platform will be served by the incoming train, and then move to that platform in time to make the train. This is a confusing experience for those who are new to the station, and is downright hostile to people with disabilities who need more time to reach the platform. What a quirky station. I'm assuming this configuration is to drive sales at the kiosk...

Rather, this configuration is the result of the the Red Line tracks merging north of JFK/UMass. Oddly, the Red Line branches parallel each other for another 1.25 miles south, which is beyond the next station, Savin Hill. This has me wondering why not merge the branches south of Savin Hill? I get that the Braintree branch must hop over the CR track at some point, but why does this have to happen between Savin Hill and JFK/UMass? Is there something operationally necessary about the current track configuration? Was it a lack of money when this was originally constructed?

From the customer's perspective it makes much more sense to to merge the branches south of Savin Hill. This would let both branches serve Savin Hill, doubling its service, and would allow the T to use a single platform at JFK/UMass for both branches.

I wonder if this is on the T's radar at all. I only ask because I remember during the Olympics that JFK/UMass was flagged as receiving a major overhaul in time for the games. Boston 2024 noted that all of its transportation projects (or if not all, most) were already paid for because they were identified in long range plans for implementation anyway.

What would an overhaul of JFK/UMass look like? Does it involve reducing the Red Line down to one platform by moving the merge farther south? How far south would the merge go? Would Savin Hill benefit, or does the merge need to be between stations?

Looking further ahead, how could the T configure JFK/UMass in a way to future-proof it? I always thought it would be nice to have an urban ring tunnel alignment follow Southampton Street, then pop up at a portal in the Red Line ROW and use the second JFK/UMass platform (the platform that would be freed up by moving the Red Line track merge south of the station). In the more immediate term, maybe the T would add another CR platform?

There's a lot going on in this section of the Red Line. What needs to happen now and for the future?

 

[F-Line to Dudley]

JFK works that way because, like Savin Hill, it was an Ashmont Branch-only station at first. They didn't build the Braintree platforms until 1988, 17 years after new branch opened. Everything else--the flyovers, the Boston Globe siding--was already there, so they had to work with what was already in-place...maddening as it is.

As for why the branches are duplicate until the Clayton St. split...the RR tracks still had daily freight jobs into Dorchester and Milton Lower Mills when the new branch was being built late-60's. The drawbridge over the Neponset River on the Old Colony mainline burned down in the mid-60's, leaving the line severed at the river but very much active to both shorelines of the river. Freights to North Quincy ran from the south out of Braintree Yard; freights to Dorchester and Milton/Lower Mills ran out of Beacon Park via Widett Circle. Burned drawbridge wasn't replaced by a new span until 1997 when commuter rail was restored, so they couldn't shut down the RR tracks during construction and sack the nearly-insolvent NYNH&H railroad with a couple years of lost freight revenue. Hence, the flyovers all done way over by Columbia instead of at Clayton St. split, and all the duplicate infrastructure down to Clayton split. Design-build began pre-MBTA during the last ~18 months of the MTA's existence, so the state didn't have a mechanism for funding a rebuild of the RR drawbridge. And since the New Haven RR was in such precarious financial state they couldn't afford to do it themselves either.

Funding snags like that were one of the reasons the MBTA was created in the first place; the MTA's charter simply wasn't flexible enough to deal with managing shared-use ROW's with a private RR's mainline as co-tenant. Prior to the T's creation in '64 the Mattapan Line was the only ROW that shared space with RR tracks (the Lower Mills branch, passing under the trolleys at Cedar Grove and running alongside to Central Ave. until about '90-92). That one-customer industrial stub was a whole world less urgent than trying to make a co-tenancy work on mission-critical mainlines like the Old Colony or Western Route (Orange-north already in planning that early on). So they needed a stronger agency charter with provisions for dealing with that. They didn't have that setup in place yet when Braintree went to design.


Relic of its time, and the unusual circumstances of this happening right in the middle of the MTA-->MBTA transition and the chaotic railroad bankruptcies. If they'd built it 5 years earlier, the drawbridge would've still been operable and they wouldn't have had to worry about preserving freight access to Lower Mills during construction. If they'd built it 5 years later, the freight railroad would've been under federal bankruptcy protection with means of publicly compensating them for the disruption in freight service. But it just so happens it went to design-build right smack in the middle of that 'tweener era when it was impossible to anticipate or compensate impacts to the private RR.

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As for a fix for JFK. . .here's an old MS Paint rendering I drew up on a thread couple years ago for double-tracking the Old Colony through Dorchester. We were discussing the state's stupid conceptual plans to widen 93 for an extended HOV lane, which would've forced both Braintree and the commuter rail tracks to be put in tunnels for a kajillion dollars. This was my less-stupid alternative to taming MassHighway's addiction to always adding more lane capacity.

(Note: crossovers placement not-to-scale)


1. Compacts Columbia Jct. to the north by eliminating all the crazy space-intensive flyovers, but still preserves the functional grade separation between the subway tracks and the yard tracks.

2. Changes the existing JFK platforms into a much saner 1 outbound island / 1 inbound island setup, without needing to demolish anything.

3. Commuter rail platform is already poured at island-platform width, so reconfiguration of the kiss-and-ride creates the room to snake the second track around the other side without modifying the platform. They could do this today if they wanted to turn the JFK platform into a passing/overtake turnout for Middleboro and Plymouth trains to leapfrog a Greenbush. Or, for simply increasing commuter rail service to JFK so the non-Greenbush branches can occasionally stop there.

4. Compacts the whole works to the south by building a shallow box tunnel underneath the Ashmont tracks and 'stacking' Ashmont on top of Braintree, such that the Ashmont tracks ride on top of the roof of the Braintee tunnel. Eliminates the flyovers, and consolidates all the electrical/signal feeds in one spot to power both 'upstairs'/'downstairs' branches. Tunnel construction is relatively cheap because all you're doing is digging a box cut underneath Ashmont that has a roof above surface level, and re-laying the Ashmont tracks on the bare concrete roof.

5. Commuter rail gets an extra track. I-93 gets a deleted surface track's worth of space to widen out the breakdown lanes.



As for the part by Savin Hill not depicted. . .

1. Before the foot of Savin Hill station the Braintee tunnel S-curves out from under the Ashmont tracks to under the Old Colony tracks in order to steer clear of Savin Hill's foundation. Ashmont goes in/out of the station on its pre-existing roadbed. Braintree continues skipping Savin Hill out of necessity for the tunnel layout (ridership isn't so high that it's worth nuking/rebuilding Savin Hill for the second time in a dozen years for a bi-level station).

2. Once 93 pulls away Braintree tunnel slides out from under the Old Colony to its current alignment and portals-up. This would happen right around the school bus yard @ Hoyt St. Everything as-is all points south of there.

3. Freeport St. and Park St. overpasses get slightly widened for an extra commuter rail track, keeping the double-tracking contiguous from South Station to Wollaston.


Pricey, but probably costs a third of the state's stupid "TUNNEL ALL THE THINGS!" concept that's just a naked highway capacity grab. And in absolute terms isn't all that expensive because it doesn't touch the stations and uses the most inexpensive form of tunneling for compacting Savin Hill.

During construction Ashmont would switch to the Braintree side, Savin Hill station would be temporarily closed, and there'd be a temporary at-grade junction with erector-set flyover ramp at Clayton St. split to keep the rest of Ashmont active while the tunnel's being dug. State's concept plan does the same. Would be a painful slow zone and a few years of putting up with train bunching, but it would keep service on both branches (excepting Savin Hill station) uninterrupted for duration of construction.

 

[Arlington]

Which is more valuable: getting the OC double tracked or keeping the Red as a 4-track RR so that we could feed 2 Red tracks into the NSRL? (Can we have both?) would we end up putting to OC into the NSRL a and not the Red if we did this?

 

[F-Line to Dudley]

Which is more valuable: getting the OC double tracked or keeping the Red as a 4-track RR so that we could feed 2 Red tracks into the NSRL? (Can we have both?) would we end up putting to OC into the NSRL a and not the Red if we did this?

For traffic management you really need to keep Red quadded or it's going to make downtown headway reliability even worse than it is now. There's too little side room past Savin Hill for putting down a grade separated flying junction that can maintain full track speed, so mainline headways are going to get maimed by the pauses at Clayton St. for one branch to clear the junction and Savin Hill station before the other can move. As it stands, Braintree always skipping Savin Hill means that in the event of simultaneous arrivals at Clayton split the Braintree train will always overtake by fat enough margin to get through JFK and Columbia Jct. without inducing a headway adjustment on the Ashmont train. You lose all that by mashing them together through the extra station and the inferior-configuration pinched junction, and the cascading effects all the way through Cambridge will suck hard.

Nothing whatsoever to do with provisions for the NSRL. That's just a serendipitous nice-to-have with the way Columbia and the Cabot Yard leads are configured. This is all about not killing downtown with degraded traffic management. MassHighway probably would've pressured them into mashing it down to 2 tracks eons ago for sake of endless add-a-lane expansion, but the drag effect Andrew-Alewife is bad enough not to even think about it.