I-90 Interchange Improvement Project & West Station | Allston

[riptide]

• 1 center express track. No crossing conflicts between locals and expresses.

This brings a two-part question to mind:

1. Why is it sometimes ok to have a center (bi-directional) express track, rather than one express track for each direction? Milford Station is set up the same way, and being in Metro-North territory on the Northeast Corridor, it no doubt handles much more traffic than West Station would. Is it mostly a matter of having universal crossovers right near the station?

2. Since West Station doesn’t seem to have any ROW width constraints that would make a four-track station design wildly more expensive than a three-track design, why choose the bi-directional express track? Why subject yourself to the inbound/outbound schedule dependencies if you don’t have to?

 

[F-Line to Dudley]

This brings a two-part question to mind:

1. Why is it sometimes ok to have a center (bi-directional) express track, rather than one express track for each direction? Milford Station is set up the same way, and being in Metro-North territory on the Northeast Corridor, it no doubt handles much more traffic than West Station would. Is it mostly a matter of having universal crossovers right near the station?

2. Since West Station doesn’t seem to have any ROW width constraints that would make a four-track station design wildly more expensive than a three-track design, why choose the bi-directional express track? Why subject yourself to the inbound/outbound schedule dependencies if you don’t have to?

There's not really going to be any inbound/outbound schedule dependencies on an express track that short. Minimum thru-Worcester headways are going to be :30 bi-directional, meaning there will only be an expressing train passing one direction or another every 15 minutes. Amtrak's tippy-top schedules are 8-10 round-trips per day, which interspersed with the thru-Worcesters is likewise too little traffic to saturate a passer that short. The track will get cleared by any movement in less than a minute, so even a sub-5 minute meet wouldn't have any conflicts. The universal crossovers do keep everything nice and elegant, and having the passer in the center keeps the conflicting movements to an absolute minimum.

The reasons for choosing a bi-directional express track instead of two unidirectional express tracks are:

• It's excessive infrastructure for the traffic levels. It's one thing if you're the New Haven Line and you've got 4 contiguous tracks the whole way to mix frequent local and express patterns...eliminates nearly all crossover moves and keeps things running fast from the lack of little performance hits while crossing over. Worcester express and Amtrak service will already need to play a couple sets of crossover games on the Regional Rail service layer cake to hop over the Newton stations on the unexpandable 2-track ROW, so an extra set of crossover moves in Allston is not meaningfully going to slow down inside-128 express service more than it already (not much) is.
• It simplifies the complicated interlockings. The crossovers will already be spanning 4 tracks on the east end for allowing universal movements on/off the Grand Junction and to/from any West platform berth, and will be merging 4 tracks into 3 to the west and shifting the express traffic from the center to the outlying Grand Junction track for passing Boston Landing station. Adding additional complexity to both ends with an extra express track will slow down the trip a little bit further, create lots more maintenance complexity, and drive up cost while ^above^ the traffic levels don't quite merit it. You could *possibly* consider it if the Grand Junction were LRT from Day 1 since that would eliminate half the complexity of the interlockings (even then it would be excessive-to-task), but not while it's already one of the most complex mainline interlockings on the system.
• The extra space is put to better use provisioning for the future LRT island platform and extra LRT track berth, correcting the lack of provisioning in MassDOT's hot-mess plan.
• The Pike is tantalizingly close to being arrow-straight with the compacted works even with the LRT provision left, so it's better all-around to keep the bulb-out to a minimum especially when it doesn't affect rail capacity in any tangible way.

 

[The EGE]

View attachment 60991

View attachment 60992

You physically cannot have a switch next to a high-level platform. Any train making the diverging move (using the orange track) will hit the platform.

A correction: it is physically possible - here's a (rare) example at New York Penn:

https://upload.wikimedia.org/wikipedia/commons/0/02/Crossover_in_Penn_Station_NY_between_Tracks_9_and_8.jpg

But you have to move the platform edge back, and thus deal with a larger gap, to make it work. Maybe worthwhile in rare cases like Penn Station where you need the flexibility, but absolutely no justification here.

 

[F-Line to Dudley]

Wait a minute...I wasn't even paying attention to the new renders of the upper level. Somehow those wasteful busways increased in capacity from 6 to 10 simultaneous bus berths in the latest redesign.

Before:

After:

Again....the only buses that are actually going to use that piggish waste of space are 3 private jitneys: a Ruggles/LMA shuttle, a Harvard U. shuttle, and a Kendall shuttle. No MBTA routes (the 64 stays on-street). No general-public boarding...only open to member institution passholders. 3 jitneys that couldn't hope to saturate 6 simultaneous berths with their frequencies now can't hope to saturate 10 simultaneous berths with their frequencies. And the jitney circulation seems to have gotten a little bit worse with the flip of the deck from the east side of Seattle St. to the west.


What are we even doing here???

 

[Tallguy]

The whole point of West Station and Regional Rail is to drive ridership to the rails by creating a reliable, clean, frequent service. Every MBTA train should be stopping, with dedicated ROWs to Harvard and Kendall. This setup is the opposite of that, with provisions for suburban coaches and car access. GJ(at least the part south of Kinney) will never see FRA service. Three tracks, two center platforms should be enough, with provisions for LRT

 

[fatnoah]

Only somewhat related, but does anyone know how well used the CSX yards in Framingham are?

FWIW, it's in the "rumor" category, but there's talk in some more rail-oriented forums of CSX eliminating road freights on the Boston & Albany east of Worcester in favor of a routing north to Clinton, and then to Framingham on the Agricultural Branch. I'm not sure how that would impact yard usage in Framingham, but it does seem like there's lots of room in the CP Yard and "extraneous bus deck" money would probably fund a lot of work in that area.