True! If we're comparing past projects, better analogs would be:
- Haymarket North Extension
- Braintree Extension
- Orange Line - Southwest Corridor
Interestingly, I think if GLX opens in a year, then all of the above projects would have taken longer than GLX from groundbreaking to completion. I could be wrong, though.
It seems to me that once we got past all of the preliminary issues, construction has moved along at a reasonable pace.
Haymarket-North the closest, because Reading Line commuter service and B&M freight service was retained alongside throughout. NETransit's MBTA service histories compendium notes no long-term suspensions of service during that build, so it probably was done around weekend bustitutions much like GLX/Lowell. Including the replacement of the former Mystic River drawbridge with the current 4-track fixed bridge, wholesale bridge replacements @ Malden Center, and relocation of the Mystic Jct. split with a (then considerably longer and more customer-active) Medford Branch to the roof of the new Wellington Tunnel pour. Given the large-scale structures that had to be accommodated with minimal disruption, that's the one that fits most closely. Oak Grove trailed the rest of the extension's opening by 2 years, but was substantially under-construction simultaneous with the rest of the project.
The SW Corridor involved an 8-year shutdown to completely knock down the old elevated NEC embankment and create the new cut...no finessing, all brute-force. Providence/Stoughton, Franklin, and Amtrak all relocated to a freshly upgraded Fairmount Line for the duration, while Needham service was suspended for the entirety. The Orange Line South Cove tunnel connection was waiting as a completed shell for 12 years prior to groundbreaking, only needing final outfitting. It was an enormous undertaking to sink the ROW, but given that most of the affected abutting properties were already acquired by MassDOT for the canceled I-95 extension and this was the cancelled highway's replacement project, they were pretty much able to make as loud a mess as they wanted cleanrooming it all. So very much a different animal in terms of accommodation. Except at cross streets accommodation was pretty much nonexistent.
Red Line South Shore extension was done in multiple chunks:
- Columbia Jct. to Quincy Ctr. yard. ROW purchased from NYNH&H July 1965, constructed 1966-71, opened 9/1/71. End of track was Granite St. south of QC (underneath present-day Stop & Shop HQ's air rights garage). Included new Neponset River Bridge and demolition of old RR drawbridge that burned down in 1966.
- Cabot Yard. Land purchased from Penn Central 12/1969, constructed 1972-74, RL lead tracks from Columbia opened June 1974; bus garage opened Dec. 1974.
- Braintree was deadlocked by disputes over station sitings (North Braintree + South Braintree vs. Quincy Adams + South Braintree) and had to be bid out for complete re-study in 1969 to break the deadlock. Planning malingered into the late-70's, and most construction ended up taking place simultaneous with the Alewife extension, 1976-80. Braintree opened 3/22/1980, QA was slated to open simultaneous but had numerous construction issues and slipped to 9/10/1983 opening.
- JFK was an Ashmont-only station until the Braintree platform opened in 1988 after a year's worth of construction.
No commuter rail traffic whatsoever, 1958-1997. Penn Central had abandoned Dover St. Yard by the time it was purchased by the state for Cabot Yard. There was no thru freight traffic Boston-Braintee after 1966 because of the burned drawbridge. Local freights ran a couple days a week from Southie to Boston Globe, the ex- Freeport St. spur that underpassed the Ashmont Branch by Savin Hill in the now-capped tunnel, and Milton Lower Mills via the Mattapan Branch (on the rail-trailed segment + a single RR track that ran alongside the High Speed Line to Central Ave.). 1 or 2 itty-bitty zit customers still existed in Quincy at time of construction (as far as North Quincy and the burnt drawbridge) but were gone by end-70's. For the Quincy Ctr.-Braintree '80 extension Braintree Yard (then as now source of daily dropoffs from Fore River Transportation off the Greenbush Line and pickups via Attleboro-Middleboro-Braintree on then-Conrail/now-CSX) was undisturbed, and multiple day-per-week service to the West Quincy Industrial Track (out-of-service since 2002) which used to have several customers and stretch within eyesight of I-93N @ the Furnace Brook Pkwy. exit. The RL-over-RR overpass and associated inclines would've been constructed here around the West Quincy jobs, which weren't frequent enough to be disrupted. So between the extreme scarcity of adjacent RR traffic to plan around and the out-of-sequence chunking of the build, not a lot of accommodation required. There was undoubtedly more street grid disruption in Quincy Ctr. during the main thrust of the '66-71 build down in the trench, but that was the only place on the whole corridor it would've been halfway-acute levels of disruption at any given time.