For the Harvard / West Station Green Line connection toward Kenmore, I wonder if using Malvern St or Babcock St to get to the existing surface B branch reservation would be cheaper than building a viaduct through the throat.
It would be horrendously slow and service-limited to run up the congested B reservation across the BU Bridge/Carlton clusterfuck, bang a hard right down any of the side streets at a signalized intersection, then cross the Pike on a sprawling viaduct. You'd get borderline-useless headways branching like that, not nearly enough for what the Urban Ring calls for.
As it stands, the Grand Junction is being accommodated through the throat in any purmutation of Pike rebuild. There is no scenario whatsoever where a 2-track ROW between West and BU Bridge would not be set aside for that line's exclusive purpose. So if you take the GJ offline to convert any part of it to light rail, that portion through the throat will be sitting there ready for a new rail use to come calling. There's no need to cheap out and maim headways by kludging together something off the surface B. Use all of it that's available by getting to the BU Bridge hillside...subway extension or surface-to-subsurface flying junction before hitting the bridge lights. On the hillside, junction east for the mainline Ring...junction west for the Harvard Branch via West. No fresh new Pike-crossing rail bridges required.
I'm also thinking there might be value in building a Green Line route originating at UMass-Boston, continuing to the JFK/UMass Red Line / commuter rail station, then along Columbia Road and Mass Ave and then into the tunnel to Kenmore, then to the BU surface stops on the B branch, then West Station, Harvard, Mass Ave to Porter Sq and Arlington Center, and then continuing along the Minuteman Commuter Bikeway ROW to Lexington Center.
The Urban Ring has a spur route proposed to JFK via Mass Ave. and Columbia Rd., coming off the SE quadrant's Dudley-Southie mainline where Melnea Cass meets Mass Ave. So it
could be a light rail appendage if any of the south half goes LRT, though lack of ROW makes the south half a better match for BRT at this juncture. However, the spur is plainly envisioned as a radial because destinations of greatest need to Dorchester + UMass are Dudley and South Boston...not downtown where they've been able to make 1 transfer to get to Kenmore for 100 years and counting. It's similar to the Harvard Branch past West mapping more to drawing 66 bus users and Allston TOD into rapid transit than somehow shortcutting any currently-established subway transfers with route duplication.
Porter and
Arlington are especially superfluous, as JFK riders already have a one-seat and 77/79 transfers at three different Red Line stations. Any rapid transit to Mass Ave. in Arlington comes from +2'ing Red to Arlington Center + Arlington Heights. You can't even get some other line's tunnel onto the Minuteman footprint because the Red tunnel goes a full 600 ft. on the Arlington side of Route 2 blocking the path.
The UR study left a lot to be desired on how to build it, but they did very clearly establish where the major demand catchments are and where those folks most need to go. That demographic data has held up very well in the >dozen years since, and probably makes for enough of a bedrock to not need a rethink whenever they get brave enough to pick this project back up for re-study. We can debate build feasibility of some of these chunked-together Green builds, but since the demand patterns have been documented to the nines you would first have to show clear-and-convincing evidence of a big miss in the original UR study. Because they already have a plan to do these routes as radials, having quantified the demand as radial-oriented. Proving their worth as a totally different breed of crosstown line takes a whole lot more than just stitching line segments together on a map and concluding they pass the eye test. You have to first
disprove the prevailing proposal casting it as a radial, then prove
all over again a greater worth as a crosstown. That's a very big overturn.
Frankly, I'd just take the radial. The demand numbers aren't voodoo, each quadrant or spur is a shorter corridor to project-manage than a monolithic 10-mile stitch job loaded with service interdependencies and ugly junction kludges, and as proposed these spurs are meant to route off multiple directions from their Ring mainlines to vary up the destinations.
http://amateurplanner.blogspot.com/2016/02/a-complete-mass-ave-in-cambridge.html has a proposal for how to create space for transit (``bus'' there, but that space should also work for Green Line trains) between Harvard Sq and Alewife Brook Parkway, and I think that cross section would also work in Boston on Mass Ave between I-90 and Melnea Cass Blvd, and on Columbia Rd between Mass Ave and the JFK/UMass Red Line / commuter rail station.
Mass Ave between Melnea Cass Blvd and Columbia Rd is currently too narrow for a transit reservation plus separate bike lanes plus space for single occupancy automobiles, but it might be worth redeveloping at higher density with greater setbacks to eventually widen the street.
Nope. Mass Ave. is 70 ft. wide curb-to-curb from Harvard to Alewife, and 70 ft. wide from Columbus Ave. to Melnea Cass. But between the river and Columbus it's only 55 ft., and in Dorchester south of Melnea Cass it's 50 ft. Columbia Rd. is 40 ft. from Mass Ave. until the median appears at the intersection of Dot Ave. They've painted bus lanes where they can, but there is absolutely no width for traffic separation on an outright majority of that route.
Wishing for a wrecking ball to create the width is not realistic when that much of the corridor falls way short.
Making space for a Green Line reservation between Alewife Brook Parkway and Arlington Center may be politically challenging.
Of course...they want their Red Line instead. A Red Line that's going to pass quietly underneath the Minuteman in a shallow Davis-style tunnel everywhere east of the high school football stadium. We should probably give it to them one of these days, as it would be a better use of resources than trying to pitch novel ways to screw up Mass Ave. after they spent a kajillion trying to fix it.
