Green Line Reconfiguration

[Arlington]

BC + South Street + Chestnut Hill Ave (which would require new platforms) account for less than 2,000 daily riders - about 13% of B Branch ridership.

(Does that include Greycliff?)

Maybe demand is choked off by how slow the B is the rest of the way in/out? How much new ridership--beyond just giving the 2k better service-- could be stimulated at those stops? Plus, would some folks at Chiswick/Sutherland ride *out* (or walk) to catch a faster trolley in from Chestnut Hill Ave?

 

[tysmith95]

BC has a shuttle that goes to Reservior and Cleveland Circle. Many students take that to save time versus taking the b line the whole way.

 

[Joel N. Weber II]

Would it make sense to run occasional trains to Boston College down the D to Reservoir, up chestnut hill ave, then on the B the rest of the way? Might reduce load on the rest of the B

If we go to 4.5 minute headways on B and inner D with 9 minute headways on C and E, we could perhaps have Riverside get 9 minute headways and BC via Reservoir get 9 minute headways with 4.5 minute headways on the Reservoir to Kenmore segment. But then what to do when Needham Green Line service is introduced becomes an awkward question.

The other challenge that would introduce is that if the BC via Reservoir train and the Riverside trains had perfectly even headways, the Riverside trains would likely get roughly 15,000 boardings per day while the BC via Reservoir trains would get roughly 10,000. It would probably become desirable to run them on something other than an even 4.5 minute headway so that there would be a slight bias towards the inner D riders ending up on the BC trains a bit more than the Riverside trains.

 

[Joel N. Weber II]

Re: C branch express

Here's a random idea that just came to me. Would it make sense to install a third express track on the C line from Cleveland Circle to St Mary's? The highest ridership stations are Cleveland Cir, Washington St, Coolidge Corner, and St Mary's so they could be the express stations. And to get the most out of it why not use the short connection to the B and extend service to Boston College?

Looking at the ROW there is plenty of space. Hell, you can still keep the parking in many places!

Now obviously I doubt ridership on the line warrants such an investment but it would greatly speed up service from the suburbs to the city.

Would it be particularly expensive?

It's probably going to be desirable to rebuild a lot of those platforms in the near future to address ADA issues and perhaps to try to move stops to the far sides of intersections to facilitate transit signal priority.

Given that roughly 2/3 of the ridership on the C branch uses those four stations, it would presumably make sense to have the express trains run through to Park St, and use single car trains that use the Kenmore loop for the local route; at 19 minutes one way, 5 cars could probably provide 8ish minute headways for the local service.

It might also be possible to make the local platforms only 100' long in that case, but I'm not sure the space that would save would be terribly exciting compared to the space the third track would take up. [Edit: Also, if all reverse peak trains make all local stops, the outbound local platforms would need to be full length unless you want to waste time in the morning at Kenmore getting people consolidated into one car on outbound trips]

 

[Joel N. Weber II]

Every B branch stop out to Washington St seems to have pretty strong ridership, and then ridership drops off except for the BC stop. That suggests that if you thought you could keep all the trains on the current route for the inner stops but redirect the outer portion to some new branch, going to Harvard around Babcock or along 57's route probably won't work so well.

However, what if we had half the trains branch off toward Brighton Center and maybe Oak Sq? Warren St to Cambridge St to Washington St in some ways is the most obvious routing, but I'm not sure how practical it would ultimately be. Most of the buildings along Warren St do not come close to the street, which might help with finding space for a transit reservation.

 

[Joel N. Weber II]

Maybe Warren St to the east edge of the Brighton High School lot then through a driveway / parking lot to the Washington St / Monestery Rd intersection and then along Washington St to a terminus a bit short of Cambridge St could work. Or maybe continue along the south edge of the high school lot to somewhere near the east edge of the St Elizabeth's Medical Center property to get to Washington St.

 

[HenryAlan]

Cleveland circle is just a short walk from Riverside. Riverside provides what basically is express service.

But Washington St and Coolidge Corner aren't. But given that it's the end of the line I suppose express service isn't really needed.

Actually, Washington St. is quite close to Beaconsfield on the D-line. When I lived in that area, I generally selected C or D for the ride home depending on which came first. By the time you reach Coolidge Corner, the ride is short enough that not having access to that D-Line based "express" option doesn't matter so much.

 

[Joel N. Weber II]

Re: Green Line to Black Falcon Terminal

https://commonwealthmagazine.org/transportation/forget-gondolas-turn-silver-line-green/ has a proposal to send some Green Line trains to Black Falcon Terminal instead of Park St.

I'd like to see the Green Line to South Station connection studied as both an all-tunnel option and as an option to have surface running from Tremont St to Kingston St (with the whole width of Essex St from Kingston St to Surface Rd turning into a portal for both the Green Line and the I-93 on ramps) to see the trade offs in cost, constructibility, and whether the surface option can get enough dedicated space to prevent it from getting stuck in traffic. Additionally, we need to understand how feasible it is to set up the tunnel option to have Dudley get Green Line service to both Park St and South Station.

I also think we ought to look at rebuilding Arlington Station with two island platforms, one on top of the other, eastbound trains on one level and westbound trains on the other, with the north track on the eastbound platform for trains to Boylston Station and Park St Station and North Station, the south track on the eastbound platform for trains to Chinatown Station and South Station, the north track on the westbound platform for trains to Kenmore, and the south track on the westbound platform for trains to Huntington Ave. We'd also add additional tunnels so that the E branch would no longer serve the existing Copley platforms but would probably get new platforms in the Copley Sq area, and have four tracks so that the Huntington Ave trains would get to / from Arlington Station on a separate track pair from the Kenmore trains, and likewise the South Station trains east of Arlington Station would get a separate track pair from the Park St trains.

If we do all this, we could probably have 7.5 minute headways on each branch with

• Boston College to Park St, Lechmere, and beyond
• Cleveland Circle to Park St, Lechmere, and beyond
• Needham to Park St, Lechmere, and beyond
• Hyde Sq to Park St, Lechmere, and beyond
• Dudley to Park St, Lechmere, and beyond
• Arlington Center to Harvard, Boston University, Kenmore, Arlington Station, Chinatown, South Station, Silver Line Way
• Boston College, Kenmore, Arlington Station, Chinatown, South Station, Black Falcon Terminal
• Riverside to Huntington Ave, Arlington Station, Chinatown, South Station, Silver Line Way
• Dudley to South Station, Silver Line Way

(Of course, the trips that get extended out to Black Falcon Terminal wouldn't necessarily have to be the Boston College trains, and more than one branch could be extended out there if the Black Falcon Terminal area gets enough ridership. And I'm not sure if it's better to give the B branch and most of the D branch one seat rides to both Park St and South Station or if transferring at Arlington Station will be popular enough that it might make sense to send all D trains to Park St and all B trains to South Station or vice versa. And obviously, these trains would make many intermediate stops that I'm not explicitly listing.)

 

[ceo]

Green Line to Seaport

Ari and his TransitMatters buddies are at it again, this time with a proposal to convert the Silver Line Transitway to light rail, connect it to the Green Line with a new tunnel under Boylston/Essex St, and reroute the Silver Line onto the surface with dedicated lanes.

I think this is a great idea, but I have some issues with their analysis. They handwave the tunnel construction costs with

Fortunately, building tunnels, as Elon Musk is finding out, is relatively easy and inexpensive with new technology. Getting people in and out of tunnels—building portals, stations, access, and egress—is a good deal more complex. Thankfully, the gap between the Green Line near Boylston Station and South Station is short, and it already has a tunnel on either end.

The problem here is that it has to start at the level of the Green Line Boylston St tunnel, which is pretty shallow, then descend going down Essex St so as to cross under the southbound Big Dig tunnel, then ascend to the level of the existing Silver Line tunnel. I'm not sure you could do that with a TBM; maybe if the launching pit was in the southeastern corner of the Public Garden, deep enough to get under the existing tunnel and join the Boylston St alignment before it hits Tremont, then you somehow ramp the tracks down from the existing tunnel. Then on the other end you'd have to close Essex between Surface Rd and Atlantic Ave for the landing pit, then build a ramp up to the SL tunnel after taking the TBM out. I don't know if there's something like a big deep sewer interceptor under Boylston though; presumably the T knows since it studied this alignment for SL phase III.

Presumably you also want to build stations at Boylston and Chinatown, which as they correctly observe is the spendy part. Also spendy is building a connection to/from the Tremont St tunnel, if there's even room to do that on the westbound-to-northbound side.

 

[JumboBuc]

Re: Green Line to Seaport

Doesn't this belong under Green Line Reconfiguration? Ari is hardly the first person to come up with this idea, as this exact proposal has been discussed a whole bunch on aB over the years (especially by van, which Ari acknowledged on Twitter over the weekend). The Green Line Reconfiguration thread was created to consolidate this discussion in one place.

 

[tysmith95]

Re: Green Line to Seaport

Honestly, as it stands now the Silver Line tunnel is useless and a waste of money. Sure it is a dedicated way, so it doesn't get stuck in traffic. However the buses crawl underground, so doesn't function any better then traffic running buses would (other then the fare gates).

It seems like a total waste when they built it. If you're gonna build a tunnel with nice stations, at least put rail or something to make the buses go faster. The money spent on that would have been better utilized if it went towards a NSRL, Red-Blue connector, Blue extension to Lynn, or many other worthy transit projects.

 

[ceo]

Re: Green Line to Seaport

Doesn't this belong under Green Line Reconfiguration? Ari is hardly the first person to come up with this idea, as this exact proposal has been discussed a whole bunch on aB over the years (especially by van, which Ari acknowledged on Twitter over the weekend). The Green Line Reconfiguration thread was created to consolidate this discussion in one place.

Point; for some reason I didn't see that thread. I'll move my comments there.

 

[ceo]

(copy-paste from my original post on the subject)

I think this is a great idea, but I have some issues with their analysis. They handwave the tunnel construction costs with

Fortunately, building tunnels, as Elon Musk is finding out, is relatively easy and inexpensive with new technology. Getting people in and out of tunnels—building portals, stations, access, and egress—is a good deal more complex. Thankfully, the gap between the Green Line near Boylston Station and South Station is short, and it already has a tunnel on either end.

The problem here is that it has to start at the level of the Green Line Boylston St tunnel, which is pretty shallow, then descend going down Essex St so as to cross under the southbound Big Dig tunnel, then ascend to the level of the existing Silver Line tunnel. I'm not sure you could do that with a TBM; maybe if the launching pit was in the southeastern corner of the Public Garden, deep enough to get under the existing tunnel and join the Boylston St alignment before it hits Tremont, then you somehow ramp the tracks down from the existing tunnel. Then on the other end you'd have to close Essex between Surface Rd and Atlantic Ave for the landing pit, then build a ramp up to the SL tunnel after taking the TBM out. I don't know if there's something like a big deep sewer interceptor under Boylston though; presumably the T knows since it studied this alignment for SL phase III.

Presumably you also want to build stations at Boylston and Chinatown, which as they correctly observe is the spendy part. Also spendy is building a connection to/from the Tremont St tunnel, if there's even room to do that on the westbound-to-northbound side.

 

[bakgwailo]

(copy-paste from my original post on the subject)

I think this is a great idea, but I have some issues with their analysis. They handwave the tunnel construction costs with

The problem here is that it has to start at the level of the Green Line Boylston St tunnel, which is pretty shallow, then descend going down Essex St so as to cross under the southbound Big Dig tunnel, then ascend to the level of the existing Silver Line tunnel. I'm not sure you could do that with a TBM; maybe if the launching pit was in the southeastern corner of the Public Garden, deep enough to get under the existing tunnel and join the Boylston St alignment before it hits Tremont, then you somehow ramp the tracks down from the existing tunnel. Then on the other end you'd have to close Essex between Surface Rd and Atlantic Ave for the landing pit, then build a ramp up to the SL tunnel after taking the TBM out. I don't know if there's something like a big deep sewer interceptor under Boylston though; presumably the T knows since it studied this alignment for SL phase III.

Presumably you also want to build stations at Boylston and Chinatown, which as they correctly observe is the spendy part. Also spendy is building a connection to/from the Tremont St tunnel, if there's even room to do that on the westbound-to-northbound side.

I think vanshnookenraggen has posted on twitter some good breakdown/maps of this and maybe is working on something a bit more? I kind of wonder if a tunnel like this would have any impact on future NSRL construction, as stuff gets pretty tight over there with the central artery tunnel, silver line tunnel, red line tunnel and the potential of the NSRL tunnel.

 

[ceo]

NSRL is going to be over toward Fort Point Channel, so it won't be affected by this.

 

[vanshnookenraggen]

The problem here is that it has to start at the level of the Green Line Boylston St tunnel, which is pretty shallow, then descend going down Essex St so as to cross under the southbound Big Dig tunnel, then ascend to the level of the existing Silver Line tunnel. I'm not sure you could do that with a TBM; maybe if the launching pit was in the southeastern corner of the Public Garden, deep enough to get under the existing tunnel and join the Boylston St alignment before it hits Tremont, then you somehow ramp the tracks down from the existing tunnel. Then on the other end you'd have to close Essex between Surface Rd and Atlantic Ave for the landing pit, then build a ramp up to the SL tunnel after taking the TBM out. I don't know if there's something like a big deep sewer interceptor under Boylston though; presumably the T knows since it studied this alignment for SL phase III.

Presumably you also want to build stations at Boylston and Chinatown, which as they correctly observe is the spendy part. Also spendy is building a connection to/from the Tremont St tunnel, if there's even room to do that on the westbound-to-northbound side.

I'm currently writing up a detailed proposal with maps but in the mean time I'll answer this. Any tunnel below Essex St is probably going to be cut and cover as there is really no room to launch a TBM and even if you did the street is so narrow you'd probably damage buildings. This isn't going to be exactly cheap or surgical. The tunnel also has to be bi-level in order to fit a station platforms in there.

There is space within the Boylston St tunnel to connect the new tunnel to, where the old portal was the tunnel opens up. It will probably require shutting down the GL for a time but there isn't going to be a better option.

As for the approach I think you're fine, that is supposing that SL Phase 3 was designed to run the same route. What killed that was the bus loop, not Essex St.

 

[vanshnookenraggen]

Re: Green Line to Seaport

Doesn't this belong under Green Line Reconfiguration? Ari is hardly the first person to come up with this idea, as this exact proposal has been discussed a whole bunch on aB over the years (especially by van, which Ari acknowledged on Twitter over the weekend). The Green Line Reconfiguration thread was created to consolidate this discussion in one place.

I should not tweet before I drink my coffee but I'm glad we worked it out.

 

[JeffDowntown]

I'm currently writing up a detailed proposal with maps but in the mean time I'll answer this. Any tunnel below Essex St is probably going to be cut and cover as there is really no room to launch a TBM and even if you did the street is so narrow you'd probably damage buildings. This isn't going to be exactly cheap or surgical. The tunnel also has to be bi-level in order to fit a station platforms in there.

There is space within the Boylston St tunnel to connect the new tunnel to, where the old portal was the tunnel opens up. It will probably require shutting down the GL for a time but there isn't going to be a better option.

As for the approach I think you're fine, that is supposing that SL Phase 3 was designed to run the same route. What killed that was the bus loop, not Essex St.

I still wonder if it would not be easier to make this a connection to outbound Green Line only, basically Seaport becomes an alternative destination to Park, North Station, Lechmere, and Boylston becomes an alternative Green Line transfer point.

I think you could merge up into the Green Line tunnel under Boylston out between Charles and Arlington Streets. The tunnel is very wide there with a big gap in the middle where the old Arlington Street Portal used to be.

Also Essex street lends itself to deep bore tunneling because of the elevation change. (Yes it is tight, but deep enough you avoid the near subsurface disruption.) Boylston/Essex rises from Charles to Washington, then falls down to South Station. So fairly straight tunneling takes you naturally under Boylston and Chinatown Stations and back to the Silver Line loop.

 

[whittle]

Is there a reason this thread is now in this forum rather than "design a better Boston"?

 

[sm89]

+1

move to appropriate forum