I believe that GLT is supposed to greatly help the B Line, but I don't think it's going to meaningfully drop the 45 minute number (helping more with reliability). People are always talking about how we should bury the B Line out to at least the BU Bridge, and I think that would do wonders for travel time at a cheaper price (though obviously not quite the same benefits).
Signal priority and all-doors boarding will help bring travel time to BC down substantially. It's fair to say >5 minutes is a guarantee, and more if MassDOT ever reconstructs the BU Bridge clusterfuck as a single-point intersection with turn lanes eliminating the two-light Carlton St. sprawl that is the biggest time chew on any B schedule. But there's no way with all of the above it's going sub-30.
One thing Comm Ave. Phase III reconstruction can do--IF the City goes with a design that centers the reservation instead of cheaping out--is serve up enough room for a turnback yard past Harvard Ave. a la Blandford Yard. And that can allow some service segmentation where headways are kept stiffest Harvard-inbound, with the shorter schedule ensuring additional reliability and tighter packing in the subway. Then you can throttle-down service up the hill where the ridership craters and sparser headways will suffice for most of the day so long as the GLT package of improvements are shorting the trip. And finally, you use the Chestnut Hill Ave. trackage to throttle-up service to BC via the C or D.
Varying up service is an old BERy idea we have an opportunity to re-embrace for the future with very reasonable things like building that Harvard Ave. turnback with the Phase III road reconstruction and better leveraging Chestnut Hill Ave.
As for the BU Bridge subway, the *only* reason to consider building that is if Urban Ring goes LRT, because tunnel is the mechanism for squaring the level difference with the Grand Junction on the bridge hillside. But by bypassing the BU Bridge lights and compressing 3 stops into 1 it's a
cosmic speedup and capacity increaser for the B in its own right. What's now 18 surface stops will drop to 14 minus the planned consolidations and TBD future consolidations. That's right in line with the C's 13 surface stops (with 2-3 likely future consolidations) in manageability.
For some reason I now have visions of a South Huntington Ave subway on my mind. Continue out on Brookline Ave to the Riverway, cut across to Huntington, and then continue as far south as you need. It covers a much denser catchment, and would serve as a renewal of service for residents there assuming that we're moving the E-Line over to the current D-Line if the North Huntington Ave subway gets built. If it can get down to Forest Hills you have relief for an already stressed Orange Line that will surely be overly stressed from a West Roxbury extension.
South Huntington definitely does not have the ridership to float subway construction. It can float a trolley because that ridership trends greater than what 60-footer buses can hold, but not a subway. Consider that there'll eventually be E-to-D connecting trackage to Brookline Village, and if the junction is configured bi-directional that means you not only can surge service on Huntington-proper but also defray any concerns on South Huntington about street-running schedules being affected by traffic by spreading out the points of origin. You could even run Hyde Square/Forest Hills to Kenmore Loop as a throttle-up.
Now, if you bury Huntington-proper in a subway to the D w/ bi-directional junction for that alt-spine magic, you can still manage the Forest Hills branch very easily by running it on the surface connector vestige...which is now 'the' branch itself. Surface stops outbound of Brookline Vill. would be:
- Riverway
- Heath St.
- VA Hospital
- Bynner St.
- Perkins St.
- Hyde Square
- Beaufort Rd.
- JP Center
- Monument
- Child St.
- FOREST HILLS
That's really not bad considering all the service throttles available. Silver Line-Washington, which majorities would agree is better off as a streetcar, is 9 surface stops at more total ridership. So if we aren't subwaying that one and its characteristics look fine for surface light rail, the South Huntington branch looks to be a near-twin.