The only way to do it as a tunnel would be to essentially build 1/3 of NSRL, so that means turning this from a $1.2 billion project into a $5 billion one, plus committing to electrify all the north-side CR lines.
Vs. kick the can down the road.
Electrifying a movable bridge is trivial. Amtrak did it with a 2 draws, 2 swings, and a lift when it electrified New Haven-Boston, and it didn't bloat the budget any.
Huh? This drawbridge doesn't interfere with NSRL in the slightest; the portals are going to be way back near the maintenance facility. Keeping the surface North Station is a necessary part of NSRL, because not all northside trains are going to run through.
Exactly, portals and needed alignments are all roughly worked out and land-banked to prevent decisions that would disrupt the potential for the NSRL.
This is part of why the GLX maintenance facility and yard are located where they are; several of the other options were rejected specifically because they conflicted with the NSRL portal locations. So it's definitely a thing that is being actively planned around.
North Station originally needed 4 drawbridges because steam locomotives are uni-directional. There was no such thing as push-pull ops back in the steam era. So every inbound train after discharging had to make a deadheading backup move into Boston Engine Terminal to get turned around, then reverse again in another deadheading move back into North Station to load for an outbound. It took twice as many movements over the drawbridges to run the same schedules as today because half of the movements were turnaround deadheads, and of course on top of that back in the day they ran much denser schedules than today. Hence, the need for 4 draws. Once the B&M converted all service to double-ended Budd RDC DMU's push-pull was in effect and trains could start laying over on the platform. And the schedules started getting slashed back, so rather than continue to maintain 4 draws for sparse use they demolished 2 of them.
www.mbta.com
Yeah, it's pretty jarring next to the beautifully soaring cable work on the Zakim.
Is this indicating the North Bank Bridge will be closed for the 31 months during Phase 1? If so that is a problem for bike access from the Somerville Community Path.
No, just that modification to the North Bank bridge would occur during that phase of work. The EA isn't definitive, as the schedule will ultimately depend on the contractor, but it contemplates multiple short term closures adding up to about a month.
Probably assembled in situ from the temp work platforms - per the above phasing, they'd have to for the middle bridge anyways because it'd be sandwiched between the new span and the remaining old one.
Definitely a concern, even if it's just the series of short closures indicated by @Stlin are the extent of it. That said, we at least have some reasonable detour options for many riders, much better than a few years ago. People going to Sullivan Square (and beyond) can take the community path extension to Washington, then drop to street level for the remaining ride to Sullivan. People going to City Square, Constitution Wharf, etc, can take the Bill Russel bridge. And though I wouldn't recommend it as currently configured, the Gilmore Bridge might also be an option. If they coned off a lane for use by bike riders during whichever days the North Bank bridge is closed, I think it would be a decent solution.
Rather interesting that the City/Commonwealth went to great effort to ensure the Charlestown Bridge replacement played nice with the Zakim. Then these lift bridges just sort of middle finger the design aesthetic.
Probably cheaper to implement than getting a navigable waterway taken out of service under US law.
