I'd be really interested in some focus group data on this. I think for transit advocates and people who work in government this framing is an obvious better statement of the benefits for the region and the long term macro economy. But then I was thinking how when I was regularly commuting Quincy-Lynn that transit was an absolute non-starter...and then how awful it was trying to take transit to Salem that one time...and then that other time to Swampscott...or how I didn't even bother trying to get to my friend's wedding in Portland that way because of bad past experiences...and then how getting to Worcester for a conference was going to take double the time on the CR. Whereas I wouldn't think twice about Quincy (Adams, mind you, so basically Braintree) and any of those destinations you mentioned. All of those you mentioned are already pretty straightforward two seat rides. I don't think telling someone they're going to knock a few minutes off a trip they're already making is as compelling to the average voter as "these places that you would never even consider going to by rail will now be open to it."
I think you raise great points, and I also would love to get some real focus group data. The point about the full range of non-Boston-centered commutes that become viable via transit with a 1SR/2SR NSRL is well-taken -- not necessarily a particularly singular node, but definitely a wide spread.
The examples I gave could indeed all be covered by 2SRs, although from Braintree we would have to cheat -- Bulfinch Triangle is only a 2SR via the Red Line. A more pertinent example might be "Brockton <> Bulfinch Triangle". But, two points for further consideration:
First, IIRC there is data suggesting that there are meaningfully distinct "North Station" and "South Station" job markets. That suggests that even though something like Lynn -> North Station -> Longwood via CR + Orange looks like a reasonable 2SR, it might still be unpalatable to some commuters.
Anecdotally: for a while I worked in the Financial District, about a 12 minute walk from South Station. Now, coming from Providence my overall commute was already pretty long, but that 12-minute walk was one last turn of the screw -- I would not have considered taking a job further north in downtown due to the reduced connectivity from Southside CR.
Which, coincidentally, brings us to my second point: the Orange Line does a
lot of heavy lifting to handle that "last 2 miles" problem. Again, anecdotally: occasionally, when it was raining or snowing, I would alight at Back Bay instead of South Station and (try to) take the Orange Line. Routinely, a train would arrive packed to the gills... you could maybe squeeze on, but that's a big maybe. Sometimes I would let the train pass and wait for the next... only to find the same condition there. This is what I mean about the Orange Line being "the original North South Rail Link";
our modern system's reliance on legacy ROWs combined with the age of downtown Boston's density creates a gap in an otherwise relatively robust network, right in the heart of the city.
As a thought exercise, I
imagined iterations of the legacy network where a cross-downtown tunnel was built early on. I then imagined a network with
two such tunnels, and suddenly we've got something that looks very similar to a NSRL RER network + a fantasy-level expanded Orange Line:
Ironically, I think that one of the other maps I drew -- imagining
a single tunnel and the ensuing capacity/frequency constraints -- is more illustrative here:
The point being that there's a huge span of territory in Metro Boston that gets funneled in to the modern Orange Line, which is forced to carry all but the Fitchburg, Fairmount, and Old Colony Line, almost exclusively on its shoulders. (The Green Line debatably shoulders this burden as well, though I'd argue less so.)
tl;dr: Two-seat-rides sometimes are okay, and sometimes they really suck, especially if the second seat is on the Orange Line. A full-build North-South Rail Link would drastically relieve the Orange Line, provide speedy 1SRs for all to
Back Bay, South Station, and North Station, provide speedy 1SRs to
Longwood Back Bay for many, and provide easy 2SRs to Longwood [
for most] and the Seaport for all.
(I know I'm preaching to the converted here, and like I said I share your interest in which message resonates more. Probably in reality the most effective iteration would be a combined one.)
