Re: Fend Funds for South Station Expansion
HSR doesn't really have any specific bearing on it. It's more NEC growth writ-large and a slowly tightening chokehold being put on every NEC user. The problem is all the cross movements into the station creating a bottleneck for trains getting quickly on/off the platforms.
-- Too many trains on the platform have to hold for conflicting moves while growing NEC traffic forces trains to spread further and further out towards the Dot Ave. side of the station and cross movements with Worcester and Fairmount. Whoever's up first on the arrival/departure gets priority, so it gets pretty hairy at 8:30am and 5:00pm.
-- What gets hit hardest is access to the commuter rail layover at Widett Circle and Amtrak layover at Southampton Yard. The cross movements in/out of the platforms have to get rationed to revenue moves first, and with so many peak-hour revenue moves there's almost no slots for non-revenue moves. So when a platform's got an arrival discharging and the next departure from that platform (because of all the other schedules are higher on the pecking order for cross movements) isn't for another 20 minutes...the idle train is stuck there. It can't scoot into the yard and free up the platform for another revenue train.
-- Amtrak gets hit especially hard by the yard moves because they have to restock the food service at Southampton and change crews between every Regional, Acela, and Lake Shore Limited run. And empty the toilets every couple of Boston-D.C. runs. They're dead in the water for however long they have to wait for a slot into Southampton. Immediate hard ceiling on Regional and Acela frequencies.
-- Yard moves hurt commuter rail when a 7-car Providence train comes in but the next outbound NEC departure is a 5-car Needham train. You can't exactly send that 7-car monster immediately back out to Needham, waste equipment where it's not needed, and induce a car shortage for the next Providence train. It's gotta wait on the platform for the next Providence departure in 20-25 minutes and induce a whole different cross movement to a whole different platform to board the Needham train. This is also why trainsets are sometimes too long or too short for the ridership they carry. Those Needhams and Franklins have to split the difference at 5 cars instead of being assigned 4 and 6. Also...easy to see where the platform layovers pinch your DMU slots.
-- Current SS has different-length platforms because of how the track fan-out is squeezed.
1) Right now Middleboro is capped at 6 cars max at SS, but all the stops on the line have 8-car platforms. Rush hour gets pretty crowded. The Buzzards Bay extension study says the only way to fit Wareham and BB ridership onto the existing 6 cars is to run 100% bi-levels. And that only buys a few years to figure out SS before they really really need 7 or 8.
2) Worcester and Providence run 7-car bi-levels today (8's occasionally on Providence). Limited selection where those can fan out, so they can't be too choosy about taking first available platform. Induces more cross movements.
3) Northeast Regionals run 10 cars at peak, with *most* (only a few outliers left) Amtrak-served NEC stops having extra-long platforms. Those have to be segregated to the very longest platforms in the middle.
What the new platforms do is spread everything out to decrease the cross movements. And stagger out the crossovers that transition the inbound + outbound mainline leads to any-direction platform tracks more gradually with more fluid sorting.
So. . .
-- See the Ft. Point Channel bridge here:
http://goo.gl/maps/xr5Yg. That's 2 tracks of Old Colony main and 2 tracks of Fairmount main coming in via Southampton Yard. Those trains would just bank hard right to the far Dot Ave. side, and multiply into platform tracks which are Old Colony- and Fairmount-only. NEC trains wouldn't have to swerve onto the Fairmount platforms anymore when traffic is heaviest. The crossovers on the Ft. Point approach get elongated so trains moving at the same time don't have to pause, they can just coast a safe distance ahead/behind by taking the leading or trailing crossovers. The only cross movements where the platform tracks divide/converge are Fairmount vs. Fairmount and Old Colony vs. Old Colony. Just like when the Red Line at Alewife crosses itself when trains reverse on either track...there will never be a headway so short on one single line to ever cause a conflict.
-- Worcester trains do the identical thing on the far Atlantic Ave. side. They hug Tracks 1 & 2 off the curve from Back Bay exclusively and divide into platform tracks without the overstuffed NEC trains having to swerve onto those platforms. Easy single-file in and out. And that's how you get the explosion of Worcester Line DMU traffic into the terminal without fouling the explosion of Worcester/Framingham traffic into the terminal.
-- NEC trains fan out to the middle and gain extra platforms, get away from Worcester, and take over what's now the Fairmount and (Greenbush?) platforms. There'll still be a little NEC-on-NEC crossing over, but they'll stay away from the other 3 mainlines. And the NEC will get the most track work at staggering out the crossovers so the NEC-vs.-NEC motion stays fluid enough to keep headways as tight as the Back Bay approach allows. Stoughton/South Coast gets its slots this way. Franklin's crunch gets eased a bit (double-tracking Readville Jct. eases it some more). Needham punts its crisis re: getting squeezed out of the mix by another decade (though its service levels really can't increase much with BBY-Forest Hills the limiter).
-- The yard moves can now happen unimpeded. When the revenue trains don't have to cross each other, the crossing moves can get properly rationed to non-revenue trains. Amtrak gets saved by being able to immediately get off the platform and restock. They can rotate discharging and boarding Regionals in an unbroken chain. Commuter rail doesn't have to lay over for 20 minutes, and they can be a LOT more precise about what size trainsets they put together for which line. DMU's get their openings to turn with the push-pulls getting off the platform so much faster.
-- The short platforms get lengthened. Being able to spread the crossovers back for fewer NEC cross movements buys more space to lengthen the Worcester platforms. You WILL be running frequent 8-car monster sets to Worcester in a few years. You may need 8-10 cars someday for Inland Regionals. The Old Colony gets its full contingent to uncap Middleboro/Cape. Anything that the NEC can possibly cross over to can be uniform length. You will, on days when track problems are screwing up the terminal, be able to stuff multiple DMU sets on one platform back-to-back sort of like they do on the B Line @ Blandford St. for Sox postgames and avoid some unnecessary yard moves by boarding the front set, then activating the next set for the next outbound, and so on.
