Figured it would be a lot lot cheaper than NSRL. Being mostly cut and cover and the real benefit would be connecting Kendall with the new Harvard owned land at Beacon Yards that is being freed up by moving the Pike.
Hardly. The Grand Junction from BU Bridge to Main St. is all on 1905 soft fill. Prior to that the railroad ran out on a causeway in the middle of the ancestral tidal river. Any tunnel construction there would require massive amounts of waterproof shielding to account for the water table in the former tidal bay in a sea level rise era where water levels in Charles Basin are going to be running consistently higher more of the time (exerting more influence on that fill water table) with acute vulnerability to overtopping. You might be able to "cut it and cover it" in a physical sense, but the waterproofing demands price it heinously more expensive per tunnel foot than standard-cost C&C.
At Main St. you'd have to be 100 ft. below ground...descending at <2% RR grades...to undercut the Red Line. On a sharp speed-killing curve negotiating the building pilings for the 8-story Cognitive Sciences building. With active pump rooms to prevent the high-and-dry and all- bedrock-anchored Red Line from succumbing to the storm drain effect of a catastrophic water breach from the lower level. Then start inclining up from that max depth under the 1969 filled-in remains of Broad Canal at Binney St. and do a little bit more waterproofing until back dry and level around Cambridge St.
It's entirely possible that tunneling under the GJ ends up nearly as expensive as the NSRL mainline tunnel (i.e. non-stations portion) because of sheer length of tunnel needing above-and-beyond waterproofing through Cambridge tidal flats vs. downtown between the I-93 slurry walls. Not even the portion of the NSRL mainline tunnel that swings slightly out under Ft. Point Channel between SS Under and the insertion point to 93 @ Northern Ave. ends up passing through much different soil properties. The poorest-drainage soil NSRL passes through is on the shallowest-dig first portions of the portal tunnels to their convergence point under the Pike Extension tunnel. And guarding against that vulnerability is much more about having multiple fail-safe flood doors near the portals themselves than soil properties on the descent. Portal locations @ Southampton and the Pike canyon are the areas of max inundation on a 50-year Boston flood map, so protection against the storm drain effect from the surface is a much bigger problem than preventing leaky walls deep below.
Through Cambridge you have to have nearly 1-3/4 mile of tunnel done with maximal leak protection on the pour AND active pumping for the storm drain effect converging on Main St./Red Line at point of maximum depth. Tack on an upper-bound per-foot construction premium for it all. The GJ "Under" tunnel is even worse by engineering dollar than waterproofing a mythical Mass Ave. subway from the Red Line @ Main St. (bedrock/former shore) to the Symphony area (former shore). The Grand Junction alignment would be even more cosmically expensive than that: over-dimension RR bore instead of Red Line-size, nearly a half-mile longer, descending much deeper, and staying more contiguously under landfill slop instead of anchoring shore-to-shore.
I see Beacon Yards as an extension of or a new Kendall Square level of development if it gets properly built out. Better connecting the Harvard R&D ecosystem with the MIT R&D ecosystem to continue to make Boston/Cambridge the undisputed top Technology and R&D center.
And it really would benefit both Kendall/Cambridge/MIT and Boston/Harvard to make that direct connection with transit versus today's bus routes that go across gridlocked city streets.
I agree. That's why you just
git-r'-dun and build the as-proposed Urban Ring BRT or LRT on that alignment sooner rather than later. NSRL is not a build prerequisite at all for ripping the GJ off the RR network and implementing a mode that can climb grades tall enough to grade-separate Mass Ave. and direct-share traffic signal cycles at Main/Broadway. Search back through many posts detailing why, but bolstered southside CR equipment independence is the only thing you have to do so north-south equipment swaps can persist couple times a week on the Worcester County detour instead of twice daily on the GJ.
The commuter rail part is almost incidental to my thinking. Just getting it out of the way mostly to make way for either light rail (green line trolley) or BRT on the surface.
Especially if NSRL is stalled then this seems the best way to actually make good use of that underused line and right of way.
This isn't borne out by study evidence. They quantified MetroWest demand to Kendall and North Station in the Worcester-NS study, and it only found demand spikes big enough to merit 5 unidirectional peak-only schedule slots each direction. And that's because those direct slots corresponded with the times of day Red and Orange were choking the hardest under load on the BBY-NS and SS-Kendall transfers. All off-peak times the ridership for the direct Purple trains evaporated because Orange and Red made NS and Kendall via transfer within 2-4 minutes of identical (because the GJ is so slow), and a stiffening of regular Worcester-SS all-day frequencies through Yawkey-BBY-SS delivered more riders via those transfers than would be delivered by forking the line @ West Station and adding more NS directs up to the GJ's very limited capacity limits.
In short, the study conclusion was: there's no natural constituency for one-seat from MetroWest to Kendall at more limited frequencies than MetroWest to 1 unified CBD destination (SS). But there IS a giant festering problem with Orange and Red collapsing under overload that will force CR riders to anticipate alternatives during the most overloaded hours. Make Orange and Red perform better under load, and all demand--rush-hour included--is essentially all-satiated by having the certainty of reliable/predictable subway service fed by ever-increasing Worcester frequencies. A fairly emphatic conclusive pair of
"FIX THE SUBWAY!" and
"IT'S THE FREQUENCIES, STUPID!" answers if ever there were, since that MetroWest audience much more highly favors greater source frequencies into already-frequent transfers than occasional alt.-routed one-seats sharply limited by the Grand Junction's native capacity.
Obviously, the Urban Ring could serve the same need just swimmingly by adding a third transfer option to the mix @ West and lessen even
further the need to provision for any Worcester-NS directs vs. just straight-on increasing regular SS frequencies. That's not a point in favor of threading two modes on top of each other on the Grand Junction ROW in some kajillion-dollar waterproofing dig. If anything it takes whatever remaining air is out of the RR tunnel idea and just ends up favoring a giddayup on the solo surface Urban Ring BRT/LRT build timetable.
I don't get this notion that's inflicted some threads here about "Well, they turfed the NSRL so I guess the next best thing is doing an East-West Rail Link because reasons." No...NSRL is about trans-CBD access. Consolation-prize "EWRL" is just a slightly modified path to the same CBD. Not thru the CBD to some truly MetroWest-inaccessible place like the North Shore or vice versa. We already know that the audience strongly favors robust Worcester frequencies meeting well-functioning transfer frequencies when it comes to all things CBD-reaching...and eschews the one-seat frequency-diluter when both pairs of the CBD transfer are on-time, meet frequently, and meet at their *most* frequent with no service forking. The goal isn't to spend billions dollars on a somewhat less dog-slow (but still pretty geometrically slow) and less frequency-diluted Grand Junction Under to artificially goose the one-seat frequencies enough to flip that equation on its head for the pride of Proving Self F***ing Right™ on an assumption.
Just follow the demand where it clearly is, and let the money follow. That means building the UR to establish that important West-Kendall-NS pipe, following through on all plans current and reasonable/additional to fix and load-balance Red+Orange's ability to perform under pressure, and cranking up mainline Worcester frequencies to amplify the effects for MetroWest commuters. That's it. Independent projects that can be mounted without much interdependence or prereqs. And in the case of the UR Brickbottom-Kenmore circuit (if assuming a Kenmore-BU Bridge subway extension with 1 campus subway station and a B Line/UR junction split)...maybe a $450M price tag managed correctly vs. $4B+ for the "East-West Rail Link" dig and surface restoration that no actionable demand data has ever asked for.
