The MassDOT and the MBTA have proposed to nullify the commitment to perform final design of the Red Line–Blue Line Connector due to the unaffordability of the construction of the project. Why hasn't the city and state try to entice investment of a blueline tunnel under the Charles to Binney Street to Grand Junction and up to Mass Ave. The investment from some of the world's largest pharmaceutical, life-science labs could only increase their potential land values (if they own it). After Mass Ave the system could extend above ground on the Grand Junction back over the river to West Station. This partnership could keep it relatively reasonable. There is potential room for a small rail yard along Fulkerson Steet.
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Because the Grand Junction is not tunnelable. It sits on soft-as-shit Cambridgeport landfill that wasn't filled until 1905-10. The entirety of the ROW west of the Main/Albany intersection to BU Bridge was constructed in 1856 on an earthen embankment hundreds of feet out in the middle of the tidal marsh that flooded with every high tide, with today's Mass Ave. grade crossing on a trestle over an inlet. Sidney St. was the marsh shoreline.
The RR performed the actual landfilling 115 years ago, hauling in the dirt that infilled both sides of it. But because it was the means of construction the roadbed under it was never repacked, and still sits on ultra-porous 1856 marsh embankment designed to let the tides saturate straight through it. The required waterproofing measures for ANY subterranean structure under that now thoroughly dev- pinned-in ROW are going to be the most expensive in Metro Boston. Moreover, the underpinning of the Red Line tunnel on Main...which was constructed on dry ancestral terra firma...creates catastrophic risk of a water breach anywhere on the Grand Junction alignment creating a storm drain effect at the sharply curved incline under Red that is capable of pooling and rising to the Red level and ruining all RL utilities as far out as Harvard. The flood controls required for that incline and underpin of Red are utter blowout-cost and extreme on the level of mechanized complexity for active-pumping way out of a torrent.
I can't imagine how this could possibly be anyone's idea of a rational pivot from the state's reluctance to cut-and-cover 6 stinking blocks of one of the widest urban renewal streets in town...so it's a Crazy Transit Pitch right there even if you can come up with a plausible frequency/capacity pipe for serving eminently plausible demand (and there are no shortage of those). But even the Crazy Pitch dies a hard death in the scruples of what it has to mount in those tunneling conditions.
It utterly amazes me when Urban Ring works just fucking fine as a 100% surface line on that side of the river that the transpo blogosphere intelligencia keeps humping at the leg of the "subway the GJ" fantasy.
Most recently exhibited with that so-called famous "expert" (some architect, not even an engineer) who got a private audience with MassDOT during the Pike/temp Charles overpass kerfuffle to waste their time pitching a tunneling of the GJ at BU Bridge to create the Pike construction staging room in lieu of the riverbank lanes. Congratulations, dude whose bio doesn't include any transit lines whatsoever, you're only the latest self-promoter in a long line who's pitched the world's most expensive spigot and made it somebody else's problem to figure out how to turn it off.
It's not realistic in the slightest. We can waterproof our existing transit lines for sea level rise without busting 7 figures systemwide and safely build NSRL + other consensus-need CBD spines because the project touches to the most flood-prone areas (esp. any/all in the Fort Point vicinity) are single-point or shallow-level by the portals to be stoppable with flood doors in multiples. Or, in the case of a future Storrow trade-in of Blue from Charles to Kenmore...enclosed as a tunnel but sitting semi-above ground level because of the recycling of highway roadpack, readily feasible under purely passive waterproofing. We can mount those kinds of builds without having our engineers' sanity questioned. It is quite another thing to attempt a linear dig through a mile's worth of contiguous ex-marsh sponge soil AND bake in a twisting incline that full mile into it which induces such extremely hard-to-stop breach risk to otherwise high-and-dry preexisting infrastructure (Red). That's like spending a kajillion dollars for Manifest Destiny "because reasons...", then taunting Charles Basin with a "Come at me, bro" on 50-year probabilities for a flood stage the dam would be powerless to even slow. And choose to play with that risk--at that expense--for a build we don't
need to at all for serving calculated demand, because the surface Urban Ring on any mode with true rapid transit frequencies has already been thoroughly vetted to handle all foreseeable corridor demand.
