Happy Easter, happy Passover, happy Marathon Weekend. Here's some assorted noodling on LRT in Allston and Brighton.
With the redevelopment of Beacon Park has come proposals for a West Station. With those proposals have come suggestions to extend an LRT branch through West Station beyond to Harvard. See for example Vanshnookenraggen's post on the topic.
These ideas interact unsurprisingly with proposals for LRT on the Grand Junction, which has been tossed around for a couple of decades now. The current Grand Junction ROW points at its western end to the site of the proposed West Station, though many of us here have suggested adding a new leg to that junction to enable Grand Junction trains to run to Kenmore. (This dovetails with larger interest in better serving the Kendall-Longwood corridor.)
Finally, there is perennial interest in providing LRT service along the corridor of the 57 bus, the former route of the "A Line". In most proposals I've seen tossed around for this, the original ROW is reactivated, branching off Comm Ave at Packard's Corner.
However, what if this Brighton Branch were fed from West Station rather than Packard's Corner?
Some of this is necessarily handwavy because the exact location and alignment through Beacon Park is only vaguely defined. However, in general we're talking about ~2,100 feet of new street-level (hopefully reservation) track, as opposed to ~3,500 feet via Brighton Ave.
One advantage of accessing the 57 corridor via West Station is the creation of a one-seat ride from Brighton to employment centers in Kendall (and potentially beyond, depending where Grand Junction services travel to on the north end).
An additional advantage is that it enables Brighton trains to avoid the Central Subway, where capacity will be at a premium. (Assume that the B and C will retain their one-seat rides into downtown; further assume that a branch to Nubian will also take up a slot, and that we can reroute the D, E, and Needham branches... somewhere. That means you've got 1 or maybe 2 slots left in the Central Subway, if we assume similar capacity to today. Just in this post here, I've already mentioned proposals for three new branches -- Brighton, Harvard, and Grand Junction.)
One downside is that this Gold Line service would not provide access to Kenmore. This is remedied via upgrades to the 57 bus itself. Assuming an LRT line is built, we may hope that it will use dedicated lanes which could then be leveraged by the bus as well. Additionally, on Commonwealth near BU, the current Green Line reservation would be made available for conversion to bus lane if the Green Line subway is extended from Kenmore west. That would leave about 3,000-4,000 feet of Comm Ave between Packard's Corner and the new portal that would either require new bus lanes, or a rebuild of the reservation to serve both LRT and BRT. An "SL57" line could then maintain the current one-seat ride to Kenmore, while also increasing frequencies along the overlapping corridor.
If we want to move into Crazy Transit Pitches, there's one step further we could take. As you can see, Comm Ave and West Station are separated by a mere 1,500 feet, or about four city blocks. With careful design and planning, the LRT ROW in Beacon Park could be connected to Comm Ave, enabling the B Line to be rerouted north.
This reroute loses Green Line service to Amory St and Babcock St, but gains better connections to services to Harvard and Kendall. Amory and Babcock would retain SL57 service.
In addition to providing one-seat connectivity from West Station to a much larger swath of Allston, Brighton, and Brookline, this connection between Commonwealth and West Station would also enable Green Line service on Commonwealth to be supplemented by Gold Line service from Kendall (not shown on the map above).
That supplementary service in turn could enable a greater number of branches to feed into the Central Subway: pre-covid, the Central Subway handled 40 tph; historically each Green Line branch has seen 6-min peak headways, requiring 10 tph per branch, thus creating our "four branch" limit. It's possible (though not certain) that outer Comm Ave could "settle" for, say, 8-min peak headways to Kenmore if they were supplemented by 8-min peak headways to Kendall and beyond. (The frequency decrease's impact could be offset in part by the new availability of one-seat rides to Kendall and Sullivan -- avoiding the need for a transfer downtown.) 8-min headways can be achieved using only 7.5 tph, which would allow the Central Subway's 40 tph to serve five branches rather than four.
In theory, a full reroute could be unnecessary; Green Line trains could continue to run straight down Comm Ave, and be supplemented by Gold Line trains coming from West Station. This would allow for the same capacity increases described above, without losing Green Line service to Amory and Babcock. Connectivity to Kendall and Harvard would be slightly reduced relative to the scenario above, but still would be perfectly serviceable.
Finally, we can come full circle: utilize our Comm Ave-West Station connection for all Gold Line service, including trains to Brighton:
I'm less keen on this version, in part because it ends up being a very tight curve for Brighton-West Station trains at Packard's Corner, and because it ends up creating a more circuitous route to West Station. However, it would have utility in an incremental build scenario, since each element (tracks on Brighton, Comm Ave-West Station connection, West Station-BU Bridge subway) will be used for multiple services and therefore would be usable even when the full interchange system isn't yet built.
~~~
Does any of this matter? Ehn.
This is a somewhat complicated solution to a somewhat unlikely scenario, in which all of the following happen:
Is there merit beyond any urgent "need"? I do think there are benefits:
With the redevelopment of Beacon Park has come proposals for a West Station. With those proposals have come suggestions to extend an LRT branch through West Station beyond to Harvard. See for example Vanshnookenraggen's post on the topic.
These ideas interact unsurprisingly with proposals for LRT on the Grand Junction, which has been tossed around for a couple of decades now. The current Grand Junction ROW points at its western end to the site of the proposed West Station, though many of us here have suggested adding a new leg to that junction to enable Grand Junction trains to run to Kenmore. (This dovetails with larger interest in better serving the Kendall-Longwood corridor.)
Finally, there is perennial interest in providing LRT service along the corridor of the 57 bus, the former route of the "A Line". In most proposals I've seen tossed around for this, the original ROW is reactivated, branching off Comm Ave at Packard's Corner.
However, what if this Brighton Branch were fed from West Station rather than Packard's Corner?
Some of this is necessarily handwavy because the exact location and alignment through Beacon Park is only vaguely defined. However, in general we're talking about ~2,100 feet of new street-level (hopefully reservation) track, as opposed to ~3,500 feet via Brighton Ave.
One advantage of accessing the 57 corridor via West Station is the creation of a one-seat ride from Brighton to employment centers in Kendall (and potentially beyond, depending where Grand Junction services travel to on the north end).
An additional advantage is that it enables Brighton trains to avoid the Central Subway, where capacity will be at a premium. (Assume that the B and C will retain their one-seat rides into downtown; further assume that a branch to Nubian will also take up a slot, and that we can reroute the D, E, and Needham branches... somewhere. That means you've got 1 or maybe 2 slots left in the Central Subway, if we assume similar capacity to today. Just in this post here, I've already mentioned proposals for three new branches -- Brighton, Harvard, and Grand Junction.)
One downside is that this Gold Line service would not provide access to Kenmore. This is remedied via upgrades to the 57 bus itself. Assuming an LRT line is built, we may hope that it will use dedicated lanes which could then be leveraged by the bus as well. Additionally, on Commonwealth near BU, the current Green Line reservation would be made available for conversion to bus lane if the Green Line subway is extended from Kenmore west. That would leave about 3,000-4,000 feet of Comm Ave between Packard's Corner and the new portal that would either require new bus lanes, or a rebuild of the reservation to serve both LRT and BRT. An "SL57" line could then maintain the current one-seat ride to Kenmore, while also increasing frequencies along the overlapping corridor.
If we want to move into Crazy Transit Pitches, there's one step further we could take. As you can see, Comm Ave and West Station are separated by a mere 1,500 feet, or about four city blocks. With careful design and planning, the LRT ROW in Beacon Park could be connected to Comm Ave, enabling the B Line to be rerouted north.
This reroute loses Green Line service to Amory St and Babcock St, but gains better connections to services to Harvard and Kendall. Amory and Babcock would retain SL57 service.
In addition to providing one-seat connectivity from West Station to a much larger swath of Allston, Brighton, and Brookline, this connection between Commonwealth and West Station would also enable Green Line service on Commonwealth to be supplemented by Gold Line service from Kendall (not shown on the map above).
That supplementary service in turn could enable a greater number of branches to feed into the Central Subway: pre-covid, the Central Subway handled 40 tph; historically each Green Line branch has seen 6-min peak headways, requiring 10 tph per branch, thus creating our "four branch" limit. It's possible (though not certain) that outer Comm Ave could "settle" for, say, 8-min peak headways to Kenmore if they were supplemented by 8-min peak headways to Kendall and beyond. (The frequency decrease's impact could be offset in part by the new availability of one-seat rides to Kendall and Sullivan -- avoiding the need for a transfer downtown.) 8-min headways can be achieved using only 7.5 tph, which would allow the Central Subway's 40 tph to serve five branches rather than four.
In theory, a full reroute could be unnecessary; Green Line trains could continue to run straight down Comm Ave, and be supplemented by Gold Line trains coming from West Station. This would allow for the same capacity increases described above, without losing Green Line service to Amory and Babcock. Connectivity to Kendall and Harvard would be slightly reduced relative to the scenario above, but still would be perfectly serviceable.
Finally, we can come full circle: utilize our Comm Ave-West Station connection for all Gold Line service, including trains to Brighton:
I'm less keen on this version, in part because it ends up being a very tight curve for Brighton-West Station trains at Packard's Corner, and because it ends up creating a more circuitous route to West Station. However, it would have utility in an incremental build scenario, since each element (tracks on Brighton, Comm Ave-West Station connection, West Station-BU Bridge subway) will be used for multiple services and therefore would be usable even when the full interchange system isn't yet built.
~~~
Does any of this matter? Ehn.
This is a somewhat complicated solution to a somewhat unlikely scenario, in which all of the following happen:
- Rider expectations return to pre-covid levels, requiring 6-min headways on Green Line branches
- Kenmore-Harvard LRT branch built
- Push to provide LRT service to 57 corridor
- Park-Nubian Branch built
- Capacity constraints in Central Subway remain the same (or D, E & Needham unable to be rerouted out)
Is there merit beyond any urgent "need"? I do think there are benefits:
- Larger reach of one-seat rides to Kendall and Sullivan via Grand Junction -- if you're going to do the LRT conversion, why not do as much with it as you can? Try to build out as full a network as possible
- Improves connectivity to West Station, creating a stronger "transit center of gravity"
- the current plans will see good(ish) ped access to the redeveloped Beacon Park, and an LRT branch to Harvard would provide reasonable transfers to areas north of the station; a Grand Junction line would provide access to Cambridgeport and Kendall; and Kenmore would be accessible via both said Green Line branch as well as continuing service to Lansdowne
- however, transit access from the south and southwest will remain very poor, including to employment centers around St Elizabeth's as well as Boston College (see map from US Census of job density below); LRT service southwestward of the station would remedy that
- in an NSRL-world, this connectivity becomes more urgent, as it will link Allston/Brighton residents to jobs located on the northside of the regional rail network
- Better transfer opportunities to Grand Junction services, and to services to Harvard
- absent this proposal, Grand Junction services will "land" at West Station, Kenmore/BU, or both. If you're a B or 57 rider, and you wish to go either to Kendall or to Harvard, you'll need to travel all the way in to BU or Kenmore, transfer, and then double back
- creating a proper transfer node at West Station will reduce crowding at, and west of, Kenmore