Seaport Transportation

[bigeman312]

There's not anywhere near enough room to rise up from the tunnel depth in only 300 ft. after the turn at the notch in the wall. The Silver Line is at intermediate, not shallow, depth around South Station because of the need to slip under the SS mezzanine level. To portal-up anywhere you'd have to keep going another block under 93 and put the portal in the Greenway adjacent to the Radian, which is only going to allow you a southbound, not northbound, surface trajectory.

If the goal was better connectivity between the SL1/SL2/SL3 and the Orange Line, how could that best be accomplished, absent political barriers, with a $100 million budget, for example.

 

[F-Line to Dudley]

If the goal was better connectivity between the SL1/SL2/SL3 and the Orange Line, how could that best be accomplished, absent political barriers, with a $100 million budget, for example.

Red Line Transformation and 3-minute headways between SS and DTX. Finish Red-Blue so DTX isn't as crowded by DTX-State double-transferees. Expand Southampton Garage so you can buy more buses to shrink Transitway headways a little bit closer to what the original Transitway scoping documents specced. Fix the crappy tunnel pavement. Optimize the shit out of the D Street light and do a fresh study of T Under D. Study guided bus steering so the speeds can improve somewhat in the tunnel.

Really...for that little money, you're talking Organization before Electronics before Concrete. Any additional tunneling in the heart of downtown is going to be heinously expensive. The whole point is that if we're going to do additional tunneling, we're going to need to do it a lot less stupidly and a lot less double-down-on-stupid than SL Phase III attempted to.

 

[bigeman312]

Red Line Transformation and 3-minute headways between SS and DTX. Finish Red-Blue so DTX isn't as crowded by DTX-State double-transferees. Expand Southampton Garage so you can buy more buses to shrink Transitway headways a little bit closer to what the original Transitway scoping documents specced. Fix the crappy tunnel pavement. Optimize the shit out of the D Street light and do a fresh study of T Under D. Study guided bus steering so the speeds can improve somewhat in the tunnel.

Really...for that little money, you're talking Organization before Electronics before Concrete. Any additional tunneling in the heart of downtown is going to be heinously expensive. The whole point is that if we're going to do additional tunneling, we're going to need to do it a lot less stupidly and a lot less double-down-on-stupid than SL Phase III attempted to.

Great! That makes perfect sense to me. Optimize the three existing heavy rail rapid transit lines first-and-foremost.

 

[F-Line to Dudley]

Great! That makes perfect sense to me. Optimize the three existing heavy rail rapid transit lines first-and-foremost.

Yeah. And it's important to note that the Silver Line itself is operating at only a fraction of its design throughput because of all the slop ops. We can do a lot to tame the dwell problems on it by simply running more buses and running them on a less-constipated ROW (pavement quality, D St., lack of State Police ramp access, lack of signaling, lack of turn guidance, etc.). What we've been putting up with the last 20 years is far inferior to what the infrastructure is natively capable of, and what the infrastructure was originally promised to carry.

Is that enough as a long-term perma-fix? Most likely not. We're going to have to get to some sort of tunnel with Orange-and-Green transfer and some sort of LRT conversion eventually. But in the short term we can bail the Silver Line out of outright crisis by tightening a lot of inexplicably loose bolts. To go along with bailing out the Red Line's congestion issues with RLT and R-B.

 

[Tallguy]

Red Line Transformation and 3-minute headways between SS and DTX. Finish Red-Blue so DTX isn't as crowded by DTX-State double-transferees. Expand Southampton Garage so you can buy more buses to shrink Transitway headways a little bit closer to what the original Transitway scoping documents specced. Fix the crappy tunnel pavement. Optimize the shit out of the D Street light and do a fresh study of T Under D. Study guided bus steering so the speeds can improve somewhat in the tunnel.

Really...for that little money, you're talking Organization before Electronics before Concrete. Any additional tunneling in the heart of downtown is going to be heinously expensive. The whole point is that if we're going to do additional tunneling, we're going to need to do it a lot less stupidly and a lot less double-down-on-stupid than SL Phase III attempted to.

https://en.m.wikipedia.org/wiki/Guided_bus
For very minimal cost, this would greatly increase speed/capacity, and would allow both BRT and LRT simultaneously

 

[Riverside]

If the goal was better connectivity between the SL1/SL2/SL3 and the Orange Line, how could that best be accomplished, absent political barriers, with a $100 million budget, for example.

Hear me out on this: break up the Silver Line.

SL1: going inbound, turn left on to Congress St rather than today's ridiculous loop. Proceed to South Station in physically separated lanes (a la Columbus Ave), optionally with an intermediate stop at A St. Going outbound, do a jog over to Haul Road and get on the Pike right away.

SL2: reroute out of the Transitway on to an extended center-running Congress St busway. Extend from South Station down Essex to Chinatown + Boylston. (Alternatively, bypass South Station and go to State via Post Office Sq.)

SL3: keep in Transitway, with frequencies maximized by devoting all electric/battery running stock to this service (with SLW short-turns).

(Images drawn from here, though I'm arguing for something slightly different there.)

It's 1.3 miles from Boylston Station to Silver Line Way. That's really not that far to implement some beefy BRT infrastructure.

Plus yes, everything that F-Line has suggested.

 

[Teban54]

Red Line Transformation and 3-minute headways between SS and DTX. Finish Red-Blue so DTX isn't as crowded by DTX-State double-transferees. Expand Southampton Garage so you can buy more buses to shrink Transitway headways a little bit closer to what the original Transitway scoping documents specced. Fix the crappy tunnel pavement. Optimize the shit out of the D Street light and do a fresh study of T Under D. Study guided bus steering so the speeds can improve somewhat in the tunnel.

Really...for that little money, you're talking Organization before Electronics before Concrete. Any additional tunneling in the heart of downtown is going to be heinously expensive. The whole point is that if we're going to do additional tunneling, we're going to need to do it a lot less stupidly and a lot less double-down-on-stupid than SL Phase III attempted to.

A very brief point about T under D: I doubt it will happen as long as SL1 and SL3 stay the way they are. The BNRD has SL1 and SL3 turning between the Transitway and D St in both directions, skipping Silver Line Way station, in order to shorten the loop-the-loop associated with it.

 

[TheRatmeister]

Hear me out on this: break up the Silver Line.

SL1: going inbound, turn left on to Congress St rather than today's ridiculous loop. Proceed to South Station in physically separated lanes (a la Columbus Ave), optionally with an intermediate stop at A St. Going outbound, do a jog over to Haul Road and get on the Pike right away.

View attachment 47849
SL2: reroute out of the Transitway on to an extended center-running Congress St busway. Extend from South Station down Essex to Chinatown + Boylston. (Alternatively, bypass South Station and go to State via Post Office Sq.)

View attachment 47850

SL3: keep in Transitway, with frequencies maximized by devoting all electric/battery running stock to this service (with SLW short-turns).

(Images drawn from here, though I'm arguing for something slightly different there.)

It's 1.3 miles from Boylston Station to Silver Line Way. That's really not that far to implement some beefy BRT infrastructure.

Plus yes, everything that F-Line has suggested.

The dedicated surface lanes downtown are an interesting idea. The SL breakup I've used when making my past maps has been:

SL1 runs direct from South Station to Logan Airport Terminals along Congress St, no intermediate stops. All Silver Line branding is dropped for this route in favor of Logan Express branding with free MBTA transfers.
SL3 is replaced with a Sullivan-Airport Station bus route, and SL branding is dropped. The rationale here is that with R/B Connector SL3 will no longer be time competitive with the Blue Line for most journeys that involve going to Downtown or Cambridge.
SL2 continues to run from South Station to Design Center through the Transitway with significantly increased frequencies. Buses would be rerouted along Harbor St rather than Northern Ave, with Harbor being restricted to bus-only use. This route would be fully converted to LRT in the future.

So what if the following modifications were made to this proposal?

1. Extend the Seaport Busway from South Station, along Surface Road, down Essex and Boylston Streets, and finally Dartmouth St all the way to Back Bay. This would primarily be used by Logan Express buses, but parts of the Boylston St route would be used by the (T)9 and (T)39
2. A new <15 min headway bus route between JFK/UMass and Boylston, with the bus infrastructure you described to better connect Seaport and downtown with more local stops. This would run alongside the T7 on a Congress St busway.

 

[kdmc]

Extend the Seaport Busway from South Station, along Surface Road, down Essex and Boylston Streets, and finally Dartmouth St all the way to Back Bay. This would primarily be used by Logan Express buses, but parts of the Boylston St route would be used by the (T)9 and (T)39

I had proposed something like that in the context of Green Line Reconfiguration, and @Riverside had some interestimg analysis of the impact of turning those roads into a transit-only corridor (assuming you mean that and not tunneling--tunneling under those roads has its own set of expensive problems): http://archboston.com/community/threads/green-line-reconfiguration.5003/post-470627

 

[TheRatmeister]

I had proposed something like that in the context of Green Line Reconfiguration, and @Riverside had some interestimg analysis of the impact of turning those roads into a transit-only corridor (assuming you mean that and not tunneling--tunneling under those roads has its own set of expensive problems): http://archboston.com/community/threads/green-line-reconfiguration.5003/post-470627

I'm going to be honest I didn't put tons of thought into the exact routing east of Boylston. There are other options that are slightly more circuitous along Kneeland and Charles that could work better, but it's more about the broad strokes and less about specifics right now.

 

[Charlie_mta]

I'm going to be honest I didn't put tons of thought into the exact routing east of Boylston. There are other options that are slightly more circuitous along Kneeland and Charles that could work better, but it's more about the broad strokes and less about specifics right now.

I still like the direct route for a GL branch to South Station, along Essex Street. Yes, there are issues with constructability (old fill, impact of construction on the existing Boylston station, etc.), but I still think if a deep bore tunnel, starting between Boylston and Arlington stations, goes deep enough, those issues may be dealt with.

 

[Teban54]

I still like the direct route for a GL branch to South Station, along Essex Street. Yes, there are issues with constructability (old fill, impact of construction on the existing Boylston station, etc.), but I still think if a deep bore tunnel, starting between Boylston and Arlington stations, goes deep enough, those issues may be dealt with.

SL Phase 3 was already supposed to be a deep bored tunnel. That wasn't enough to deal with all the other challenges, like rapid changes in grades, underpinning complex stations, narrow streets, etc.

 

[Riverside]

SL1 runs direct from South Station to Logan Airport Terminals along Congress St, no intermediate stops. All Silver Line branding is dropped for this route in favor of Logan Express branding with free MBTA transfers.

Yeah, this is mostly my conclusion as well. One alternative worth considering also would be running the service into the new South Station bus terminal.

SL3 is replaced with a Sullivan-Airport Station bus route, and SL branding is dropped. The rationale here is that with R/B Connector SL3 will no longer be time competitive with the Blue Line for most journeys that involve going to Downtown or Cambridge.

My analysis suggests that there may be a non-trivial Chelsea <> Seaport market, so I've typically kept SL3 as-is, or striking a middle ground by continuing to run to South Station but on the surface. Alternatively, if we build a Congress St busway that extends from Haymarket into the Seaport, then potentially an extension of the T111 (which serves the residential areas of Chelsea better) could work instead/better.

Extend the Seaport Busway from South Station, along Surface Road, down Essex and Boylston Streets, and finally Dartmouth St all the way to Back Bay. This would primarily be used by Logan Express buses, but parts of the Boylston St route would be used by the (T)9 and (T)39

Yeah, as @kdmc noted, Essex probably needs to maintain some access for private traffic. Buuuuuuuut.... you could steal the other lane of traffic for a contraflow lane. It gets tight in the block between Washington and Tremont, but mayyyybe you could squeeze two bus lanes and a private lane, though I'm skeptical.

In terms of wider streets, a combination of Surface Road + Kneeland + Stuart gets you at least to Park Plaza. The options are less ideal after that... perhaps you could cut up to Boylston? But then the question becomes how to connect to the Green Line and Orange Line around Copley/Back Bay, particularly since Stuart + Kneeland offer poor transfers to either Chinatown or TMC.

But to your point, the busway could be used by several routes and extensions of routes (T8, T9, T39, 55, 11, the 500s). There is a network of radial surface routes that operate wholly within the "Inner Belt" and which currently truncate themselves at the first major transfer point they reach, but which are clearly oriented toward downtown. Stronger infrastructure in the congested core could enable modest extensions of those routes, and potentially relieve some pressure on the subway.

 

[TheRatmeister]

SL Phase 3 was already supposed to be a deep bored tunnel. That wasn't enough to deal with all the other challenges, like rapid changes in grades, underpinning complex stations, narrow streets, etc.

Of course you could always go even deeper but at that point cost has scaled even more drastically and completely beyond any benefits the project would bring.

 

[Riverside]

Some further discussion on busways here in the Reasonable Transit Pitches thread.

 

[TheRatmeister]

My analysis suggests that there may be a non-trivial Chelsea <> Seaport market, so I've typically kept SL3 as-is, or striking a middle ground by continuing to run to South Station but on the surface. Alternatively, if we build a Congress St busway that extends from Haymarket into the Seaport, then potentially an extension of the T111 (which serves the residential areas of Chelsea better) could work instead/better.

A rough analysis suggests a maximum ~8100 pax per week (As of 2022) travel from the Chelsea-Airport section to WTC (Surface), SLW, WTC (Transitway), and Courthouse.

Spoiler: Key Assumption Made

The key assumption made in this table is that riders who board at SLW and WTC do not travel to WTC or Courthouse, only South Station. While I'm sure a few riders do make these trips, I can't imagine it's a significant proportion, and even then that just makes the case for SL3 post RBC even worse if more people are traveling all the way to South Station.

Just for some reference, that's fewer than the number of riders between Haymarket and this 2500ft section of the 111 in Chelsea:

So basically my question is, does a future Chelsea-Seaport route even deserve Key Bus Route service, let alone Silver Line frequencies (Outside of rush hour)? My hunch says no, but obviously there is plenty of room for personal opinion here.

 

[Teban54]

Hear me out on this: break up the Silver Line.

SL1: going inbound, turn left on to Congress St rather than today's ridiculous loop. Proceed to South Station in physically separated lanes (a la Columbus Ave), optionally with an intermediate stop at A St. Going outbound, do a jog over to Haul Road and get on the Pike right away.

View attachment 47849
SL2: reroute out of the Transitway on to an extended center-running Congress St busway. Extend from South Station down Essex to Chinatown + Boylston. (Alternatively, bypass South Station and go to State via Post Office Sq.)

View attachment 47850

SL3: keep in Transitway, with frequencies maximized by devoting all electric/battery running stock to this service (with SLW short-turns).

(Images drawn from here, though I'm arguing for something slightly different there.)

Is this set of proposals assuming the $100 mil budget and thus no GLR? Then yeah, I do think something along the lines (plus a Summer St BRT system) is probably among the best budget plans.

However, I think in the most realistic real-world scenario, arguing for Congress St bus lanes when Summer St just went through a redesign to include them (albeit imperfectly) is an uphill battle, even though it would dramatically improve SL1.

SL1 runs direct from South Station to Logan Airport Terminals along Congress St, no intermediate stops. All Silver Line branding is dropped for this route in favor of Logan Express branding with free MBTA transfers.

Yeah, the idea of making SL1 a pseudo SS-Logan express is a good one despite not being new. But, for one thing, I'm concerned about using Logan Express branding for it. People, especially tourists and occasional transit users (including suburbians), are unlikely to treat Logan Express as proper rapid transit, especially if they have a different fare structure and/or are not properly advertised on T maps (at least one of them seems highly likely). The fact that most other Logan Express are long-distance suburban routes certainly doesn't make it any better.

For another thing, if you're running on Congress St anyway, making a stop at where @Riverside indicated wouldn't hurt.

SL2 continues to run from South Station to Design Center through the Transitway with significantly increased frequencies. Buses would be rerouted along Harbor St rather than Northern Ave, with Harbor being restricted to bus-only use. This route would be fully converted to LRT in the future.

Does anyone know why SL2 was routed via Northern Ave (instead of Harbor St) in the first place? That seems like an odd decision. Perhaps it's to provide fast bidirectional service to the Northern Ave / Tide St intersection, which borders a bunch of companies and factories to the north?

Regardless, I speculate you might be able to get by without bus lanes over there, as traffic probably isn't too bad.

A new <15 min headway bus route between JFK/UMass and Boylston, with the bus infrastructure you described to better connect Seaport and downtown with more local stops. This would run alongside the T7 on a Congress St busway.

Are you saying something like this?

That's actually a very interesting and relevant proposal. One issue I always had with the (T)7 (despite its popularity, especially with commuters) is that it serves too little of South Boston. In addition to connecting to Seaport, the route above also gives a greater part of Southie a one-seat ride to South Station and Financial District, which almost guarantees popularity -- South Boston is the most downtown-centric neighborhood anywhere in Boston.

I'd terminate the route at Andrew, though. You're unlikely to get many commuter rail riders from JFK/UMass, as they'll probably just ride to South Station.

Of course you could always go even deeper but at that point cost has scaled even more drastically and completely beyond any benefits the project would bring.

You can't go deeper if you want to connect to the existing SL platforms at South Station. The SL Phase III proposal already did almost the maximum grade between South Station and Chinatown, in order to have a double stacked SL Chinatown station (platforms on two different levels due to limited ROW width) below OL Chinatown.

 

[Teban54]

Regarding the necessity of SL3:

First of all, demand for this segment is not just from Chelsea, but from Airport Station and thus the entire Blue Line. That captures an even bigger population base than Chelsea (especially with ongoing TOD). Likewise, at the other end, both South Station (FiDi, Red Line transfer, Commuter Rail transfer) and Seaport (jobs, recreational) are important destinations. Going from Blue Line to Seaport is especially nasty, as virtually no proposals allow a convenient transfer from the Transitway to any of the Blue Line stations. Your best shot is the downtown bus priority corridor, which, as currently planned, stops on Summer St which is less convenient for Seaport destinations due to the elevation difference.

Travel Time:

Direction	Red-Blue	SL3 (Current)	SL3 (Simplified)*
Airport -> Courthouse	23.5 - 24 min	33 min	22 - 27 min**
Airport -> South Station	20 - 20.5 min	34 min	24 - 29 min
Courthouse -> Airport	23.5 - 24 min	23 min	19 - 22 min**
South Station -> Airport	20 - 20.5 min	25 min	21 - 24 min

* Times are Google Maps estimates and are very uncertain
** New "Courthouse" stop on Congress St

"Current" refers to SL3's current loop-the-loop route, and "Simplified" refers to a largely-surface SL3 similar to @Riverside's SL1 proposal. These travel times account for transfer walkway times and wait times of all services taken (including taking BL, even for the SL3 trips, as the passenger is assumed to come from outer BL). They do not consider time to exit South Station.

Spoiler: Methodology, assumptions and detailed results

Expected wait times are half of the route's headway.

BL-RL-SL travel times and their sources:

• Blue Line, Airport -- Government Center: 7.5 min (TransitMatters dashboard, 2018 first half)
  • Chose 2018 first half, because the second half had what looks like a slow zone that got resolved in a few months
• Blue Line, Government Center -- Charles/MGH: 1.5-2 min (using RL's Charles-Park as estimate, TransitMatters dashboard, 2018 first half)
  • Travel time is about 53 sec
  • Dwell time: BL average on this segment is 40 sec, but transfer stations are likely longer, so I guessed 40-70 sec
• Charles/MGH transfer:
  • Assume 2 min walking
  • BL was running 5:50 headways in 2019, and RL was 4:50
  • RL Transformation aims for 3-min headways
  • So I assume 3-min RL headways and 5-min BL headways
• Red Line, Charles/MGH -- South Station: 4 min (TransitMatters dashboard, 2018 first half)
• South Station transfer:
  • Assume 1 min walking
  • SL1/2/3/W combined have average 2.6-min headways during rush hours in Winter 2024, and 4.3-min headways during midday
  • If Winter 2020 data is used, these two figures are 1.9 and 3.4 respectively
  • Thus, assume 3-min SL headways
• Silver Line, South Station -- Courthouse: 2 min (current schedule)

Current SL3 travel times: (current schedule GTFS)

Direction	All-day average	All-day max
Airport -> Courthouse	22 min	31 min
Airport -> South Station	23 min	32 min
South Station -> Airport	14 min	19 min
Courthouse -> Airport	12 min	17 min

Current SL3 wait times:

• 2024 headways: 9-10 min peak, 15 min midday
• 2019 headways: 10-12 min peak, 15 min midday
• Thus, assume 12 min SL3 headways and 6 min waiting time

For transfer between BL and SL3 at Airport, a 2.5 min walk is assumed (as the inbound BL platform is a hassle to get to).

Simplified SL3 travel times:

• Based on Google Maps directions, outbound SS -> Airport trip takes "typically 8-16 min" during most of the day, and "9-20 min" during PM peak. The route is the same as what @Riverside suggested.
• Inbound trip is harder to analyze, as cars need to make a detour loop through airport rental but SL3 doesn't need to. With the loop, Google Maps says "typically 10-20 min" most of the day, but "14-26 min" during both rush hours. The loop takes about 2 min to complete.
• Accounting for bus lanes, I choose a blend of 10-13 min outbound and 13-18 min inbound to/from South Station. (The outbound estimate may be conservative when compared to the current loop-the-loop.)
• Subtract 2 min for Courthouse.

My interpretations: If our only objective is to improve travel times to South Station and Courthouse (which itself is a question -- see the next comment),

• The current SL3's route has a lot of room for improvement, particularly because of the loop-the-loop. (Having transit priority on the existing route will certainly help, but I'm pessimistic about it, especially in the Ted.)
• But even with the current route, outbound Courthouse -> Airport is already time-competitive with Red-Blue. This is likely due to both Red-Blue's extra transfer, and the outbound route facing less traffic in Seaport than the inbound route.
• A change in route can potentially improve SL3's competitiveness even further, particularly in the inbound direction.
• For trips to/from South Station, Red-Blue is mostly better (due to both not being a 3SR and SL3's slightly longer distance), but SL3 can be quite close in travel time with a more direct route.

One important point is that SL3's competitiveness is significantly hampered by its long headways. Even though it has Key Bus Route-level service, it's still nowhere close to Red and Blue lines' headways. All my travel time estimates added an extra 6-min because of it. This would suggest:

• In the short term, there may be value in making SL3 more frequent. The question is whether there's sufficient demand.
• In the long term, if a third Ted Williams transit bore happens, it can be quite competitive for bringing BL and Chelsea riders to both Seaport and South Station, as it helps with both headways and travel times.

One last point: All this is assuming the passenger comes from the Blue Line. If someone is riding from Chelsea, the calculus changes completely.

 

[Teban54]

Demand factors

A rough analysis suggests a maximum ~8100 pax per week (As of 2022) travel from the Chelsea-Airport section to WTC (Surface), SLW, WTC (Transitway), and Courthouse.View attachment 47937

Spoiler: Key Assumption Made

The key assumption made in this table is that riders who board at SLW and WTC do not travel to WTC or Courthouse, only South Station. While I'm sure a few riders do make these trips, I can't imagine it's a significant proportion, and even then that just makes the case for SL3 post RBC even worse if more people are traveling all the way to South Station.

Just for some reference, that's fewer than the number of riders between Haymarket and this 2500ft section of the 111 in Chelsea:
View attachment 47938
So basically my question is, does a future Chelsea-Seaport route even deserve Key Bus Route service, let alone Silver Line frequencies (Outside of rush hour)? My hunch says no, but obviously there is plenty of room for personal opinion here.

I would definitely not say 8100 pax per week (which, not to forget, completely ignores South Station, and traffic between Chelsea and Airport) is too low for a Key Bus Route-level service. This is:

• Similar to the 15's riders at Nubian and Ruggles combined (8300-9600)
• Similar to the 23's riders at either Ruggles (7100-7900) or Nubian (8700-8900)
• Similar to the 71's and 73's riders at Harvard combined (7400-11580)
• Similar to the combined boardings of Malden Center's top three bus routes at that stop (8100)
  • The three routes are 101, 104 and 108, with two of them to be converted to Frequent Bus Routes
• Higher than the individual routes of 104 and 109 at Sullivan, and 60% of these two routes combined
  • These routes will become a single route T109 at Sullivan
• More than twice of the 101's boardings at Sullivan (3100-3500), while the 101 will also be converted to a Frequent Bus Route
• Higher than any circumferential route's boardings at the aforementioned bus hubs

Comparing any Key Bus Route or Frequent Bus Route to the 111 is an unfair comparison, as the 111 is really a "Mega Key Bus Route". Its frequency during rush hours is the best among all Frequent Bus Routes under BNRD:

Also, the 111 is clearly the primary service for Chelsea residents, and people take it to get to most of Boston (I'd guess even including northern Red Line). The 111's stops are also closer to density and easier to access than the SL3 stations. In contrast, the SL3 serves a much more dedicated market. If anything, its ridership actually exceeded my expectations.

What's also interesting from your analysis is that, with your assumption, almost twice as many SL3 riders from Airport and north alight at Seaport (8100) than at South Station (4300). This shows demand for Seaport is strong and unlikely to be massively depleted by Red-Blue. (Part of it could be that better alternatives to get to South Station exist, including walking to FiDi offices from State, Aquarium or even Haymarket.)

(On the other hand, there seems to be significant demand for WTC and SLW stations from SL3. Each one has more alightings higher than Courthouse, and the two combined have more alightings than South Station. This suggests it may even be worthwhile to not shorten SL3's route, and let it serve WTC at the cost of a longer trip to South Station and Courthouse.)

 

[real_EthanHunt]

Are you saying something like this?
View attachment 47994

The T12 of BNRD is serving this. Direct connection from Andrew to Seaport along a D St bus corridor without the circuitous route.