Re: Storm surge in Boston
We're not nearly as vulnerable as NYC. Reasons:
-- Boston Harbor empties much faster to open ocean than New York Harbor. Mouth of our harbor is wider and much closer, so we don't get the high-tide-piled-upon-high-tide effect that Sandy had in NYC...where the previous high tide never abated at all before the second high doubled it up. Long Island Sound with a surge coming from due east traps all that water for 100+ miles in length with only a 4-6 mile mouth vs. 6-7 mile length and 4-5 mile mouth for Boston Harbor. It's not impossible, but it takes a surge a hell of a lot more than Sandy to do it.
-- We're less pinned in than NYC. The Lower Bay of NYC is narrow and close; Upper Bay has an extremely narrow mouth to empty into the Lower Bay. And unlike us those inner bays directly abut open ocean and don't have a deeper transition zone like the Outer Bay here. That means a surge piles up frighteningly fast entering their bays, and in the case of the Upper Bay an agonizingly slow drain-out of Hoboken and Jersey City. If we did get a perfect surge into the Harbor we'd have much more time to evacuate and defend than Staten Island and Lower Manhattan.
-- Barrier Islands. Boston Harbor is chopped up by so many harbor islands and rock outcrops that there isn't a single straight line from the mainland into open ocean that doesn't hit additional land. If you're counting smaller outcrops: multiple pieces of land. NYC has nothing protecting it in the Lower Bay except Sandy Hook and Breezy Point, which of course were so completely inundated they did nothing. The Bronx is better-protected from a straight shot and fast surge via Long Island Sound...the CT shoreline got it much much worse. But that's counterbalanced by the tide drainage issues with the Sound, so they get a slower rise that just doesn't abate for multiple tides.
-- The Cape. Cape's much thicker a barrier than Fire Island, Long Beach, and the Rockaways for south-facing inundation on Long Island. NJ's barrier islands were similarly impotent Sandy overwhelmed that protection. There's almost nothing other than a tsunami that's going to overwhelm down Cape.
-- Hull and Winthrop. They're positioned like your fingers making a "C", and absorb the due-east and NNE winds/surges that the Cape doesn't. They get fucked up in storms so we don't have to. Nahant acts as a secondary shield for NW surges.
-- Wind direction. Hurricanes and Nor'easters usually don't blow in a killshot direction towards us where they'd thread the needle from open ocean through the least-protected part of the Harbor. It's not how they spin or where 90%+ of the storm tracks put them. They're usually pulling out to sea and heading for Nova Scotia before the surge comes in that direction. NYC and NJ are angled in the same way that North Carolina is, so the odds are higher that a storm maintaining its strength and hugging the coast instead of taking the typical ENE turn will do similar damage as hurricanes often do to North Carolina and its barrier islands. Not to say it's impossible, but a storm has got to have a really really counterintutive track to throw a killshot surge on a straight line to Boston. Sandy's track wasn't counterintuitive...it's size and hybrid-ness were. It's upper South Shore (Scituate, Hull, etc.) and Gloucester/Rockport that face the ESE direction outside of Cape protection that NYC/NJ and the Chesapeake do. And that's why they got fucked up by the surge in Hurricane Bob, Blizzard of '78, etc. while Boston Harbor didn't. (I'll discount 1938 as apples-oranges because lack of warning was the main factor in that destruction.)
Our flood risks tend to be rain-related like the Flood of '96 where inland drainage and shitty soil absorption do us in. The Charles and Mystic, even when dammed, aren't great at draining when there's an inland inundation at the source. The Muddy River is infamous for flooding at the drop of a hat, and we get a shitload of trees overturning and flooded basements when saturated soil turns to jello consistency. Especially in the Back Bay landfill zone where it's still resting on tidal flat mush. The good news is that's a much slower rise than a storm surge. The bad news is it's more frequent, and will be more prevalent with wild weather swings (especially flash snowmelt).
As for the tunnels, we don't have that many at the level of risk NYC has. We don't have subways hugging the harbor (i.e. nothing along Atlantic Ave.). The Sumner and Callahan mouths spit out further inland on both sides than a Harbor inundation would reach. The Big Dig, Pike Tunnel, Ted, and Transitway have modern flood controls. Big Dig also has portals built into the sides of artificial hills and that rise in the roadway after the inclines down, so its geometry prevents inundation outside the exit ramps (plus the pump system is overbuilt). The Red Line does have steel flood doors just south of South Station to protect it from a Ft. Point Channel inundation.
Aquarium, SS, and Maverick are the only 3 stops where an inundation is within reach of the station entrances (and Maverick is above sea level just enough to be a non-factor). SS lobby does get pretty drippy in rain events and would be vulnerable to Ft. Point overtopping the Financial District (which it does routinely on the Southie side...very rarely on the SS side). But Aquarium doesn't ever seem to get wet even in rain, and the Silver Line stops are far enough inland that it would probably take a >100-year flood overwhelming the Seaport district to even reach the station entrances. And North Station is well-protected by the Charles Dam and the Green/Orange superstation and relocated GL tunnel being grafted onto the Garden basement at shallow depth and connected to that building's modern pumping.
Of course...rain events are risky here. Especially the Green Line where we live and die with the sandbags at the Fenway portal preventing Kenmore from getting destroyed like it was in 1996 and 1962. They definitely need strong flood doors there. And we saw in the Floods of 2010 how poorly the downtown transfer stations hold their water. And don't get me started about groundwater in the Big Dig.
As for surface, commuter rail isn't at much risk because we don't (yet) go underground like Penn or Grand Central, we don't have any 3rd rail electrification that gets shorted out like Metro North and Long Island RR, and we don't have main layover yards right on the fricking water like LIRR and NJ Transit do. BET is in a sand pit behind the Charles Dam, Widett Circle is out of reach of a Ft. Point inundation, Readville is far inland, and Greenbush and Rockport are the only outer layovers close to water. We don't risk equipment getting destroyed like some of those pictures of Metro North Hudson Line and NJ Transit trains with water up to the top of the wheels. At worst, Red Line Cabot Yard would have to scramble trains parked in the loop area by Ft. Point Channel further back to the Haul Rd. side, and Blue Line may have to evacuate Orient Heights (although no 3rd rail = no short-outs if they drop the pantographs on the parked trains).
So, yeah, I think we do have some work to do, but it tilts more to the 100-year rain, snow, and saturation events than shoreline inundation. Not that we shouldn't be planning for that, but it's a clear #2 on the flood worry list here as opposed to NYC which has got to get majorly prepared for more Sandys.
