- Jun 26, 2013
- Reaction score
The point of variable pairings would be precisely to not "create/manage/get some likely wildly-interlined schedules." You don't schedule out 16 regular service patterns, you schedule out four (the letters) to roughly the the same extent they do now, and then you on-the-fly assign number termini to the the trains when they turn around at their letter termini. Or to the extent you do schedule out all 16, you don't publish that schedule. So when a train turns around at, say, Riverside, the system dispatcher looks at what's ahead of it on the line and determines whether it should go all the way to Medford/Tufts or Union, or whether needs to short turn at North Station or GC. A rather simple little scheduling algorithm could run behind the scenes guiding those dispatching decisions, but also crucially this would allow for a lot of flexibility when unplanned service interruptions or disruptions pop up.Going from 4 regular service patterns (in addition to the rando exceptions and peak-hour short-turns) to up to 16 regular service patterns doesn't seem to be particularly intuitive for new or infrequent users.
B1 B2 B3 B4
C1 C2 C3 C4
D1 D2 D3 D4
E1 E2 E3 E4
Also, woe be the service planner, operations manager, and operators/motorpersons that have to create/manage/get some likely wildly-interlined schedules.
Infrequent users don't need to know what's going on behind the scenes at all. All they need to know is, e.g., "I need an E train to go to the MFA" or "I need a 1 or 2 to go to the Science Museum" or "any number will take me to Park Street from the Back Bay." This is no different from, say, "I need a B, C, or D to get to Fenway Park."
With the set pairings across the GL branches on both sides of the Charles, you'll end up with a situation where a car accident or a track problem at, e.g., Brigham Circle will shut down service between Medford/Tufts and Lechmere. That doesn't seem to make a lot of sense. With more flexible pairings, you'd be able to optimize more consistent and shorter headways across the entire system. And you could very well end up with fewer short turns at GC or NS, which would be a win for connectivity.
With set pairings you'll also end up with a situation where a commuter from Ball Square will never have a one-seat ride to their job in Kenmore Square, while a commuter from Allston/Brighton will never have a one-seat ride to their job at North Station. With more on the fly mix-and-match flexibility, those commuters would usually-but-not-always gets a one seat ride, and on the days that they don't they could wait for the next train in any station along the central subway just like they do now.
Given how much tech workers love Somerville, I feel like switching the Medford/Tufts branch from D to E could actually be a big deal for the growing tech cluster in the Fenway / Kenmore area. With more flexible pairings, that wouldn't be a thing.