Hits all the right notes without much fluff. F-Line's going to hate the assumption that the GJ transit is DMUs from West to North. Mentioning the Kendall headhouses, platforms, and portal is good. This is the first I've heard of a bus bridge from Cambridge Crossing to Inner Belt.
The DMU thang was on the midrange Rail Vision options, so it's not surprising they rolled with it verbatim as a best-odds pick. But it is asterisked to hell in the RV as dependent on further capacity analysis (which hasn't been done). That's where it's going to run into problems trying to make Urban Rail headways. Doubly so because if it's being opened up to this niche-y dinky then the state-level politics of token quantities of Worcester-NS one-seats is going to interfere and really push the schedules beyond what'll support :15 bi-directional headways. Double-tracking the GJ doesn't necessarily move that needle at all because # of on-line stations and the North Station terminal district approach are the time chews and pinch points that jeopardize the very frequency target that nets useful-enough service.
It's not
this study's fault that the scheme is a house of cards. It's the fact that West-North DMU dinky has been so prominently featured on multiple state-level proposals dating back to Gov. Patrick's IOC wet-kiss vaporware "Indigoes 2024" map without ever getting any formal workup whatsoever on headways and crossing impacts. That only exists in the GJ Transportation Study for part-time unidirectional Worcester runs. The Kendall study couldn't stick its necks out any further than "develop a transportation concept".
I wouldn't get hopes up for this, because they could do little more than shove everything on the Rail Vision for answering the too-numerous TBD's about throughput. The RV Alts. have always been structured to make West-North one of the first/quickest cuts if they run into a headwind on achievable capacity, so we sort of know up-front the odds aren't real great. When all is said and done, I still think we'll be studying something
off the RR mode to find the schedules frequent enough to match the corridor demand forecast. Thankfully they are planning to update that forecast so we'll have fresh numbers to show what baseline frequency is the must-have.
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The Innerbelt bridge could be 1 of 2 things: (1) Urban Ring-derivative bus-only bridge, so...again...scraped up from prior studies; or (2) an actual city-street extension of Innerbelt Rd. The UR MIS had bupkis about where such a BRT bridge would actually exist through the spaghetti rail junctions at Brickbottom, so it's impossible to tell which of the 2 this refers to. And I guess the Kendall study doesn't know either because they make no mention. Nothing really to say here because we don't know any tangible facts about it. Building "a" bridge is certainly doable. Whether that bridge is on an alignment that facilitates Ring-like BRT service without ham-fisted turning is another matter. An east-west bridge would've been more favorable for direct service than a north-south bridge, but the UR MIS wouldn't even say that much specific.
It won't be cheap, that's for sure. If drawing a straight line as if Innerbelt is going to connect to Lechmere it would have to pass over a minimum of 13 tracks, including the rump-end of some elevated GLX infrastructure where the freight wraparound from the Lowell Line passes under the GL yard leads. Then it has to quickly get down behind the Shell station on O'Brien Hwy. before the GLX Lechmere viaduct extension and sharply turn towards Water St. Tall and long bridge. Bend closer to O'Brien...more elevated + ground-level spaghetti. Bend closer to Boston Engine Terminal...fewer to no elevated junk but longer length and many more tracks to overpass.
FWIW...I think an actual city-street extension of Innerbelt would be rad as hell for general-purpose linkage, especially if it came with a project to widen the makeshift tunnel under the Lowell Line to have full sidewalks. But that bridge alignment question around spaghetti junction is a feasibility crapshoot, so probably has to be kept on a short leash for any prospective wishlists.
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The bus prioritization stuff is genuinely good. As is repairing the advancing decay on the Red Line platforms and improving ped flow at the egress level. That station gets so dangerously crowded at rush; it can't go on any longer with 1912-sized exit stairs.
I'm not sure the flood risk to the portal is as great as they claim, however. The portal is up pretty high above Charles Basin to align with the Longfellow approach, and Main St. is ancestral terra firma here so there's no landfill anywhere on the Cambridge Tunnel alignment. It's surrounded
very nearby on all sides by landfill to Vassar St., but the tunnel itself is thoroughly bedrocked.