Thanks! I wasn't perfectly clear the first time around, but you got the meaning of my question. Certainly, connecting Sullivan to Lechmere is too messy to be a 1st generation build, but when it comes to doing the 2nd generation stuff do you think problems #1 and #2 can be mitigated by taking some industrial land via eminent domain? How important is it to grade separate the community path from a single track LRT track?
Well, to be clear, I am an overenthusiastic amateur with no formal training, so what I think may be quite wrong.
Could eminent domain smooth out the curves and shorten the diversion distance? Hmmm, maybe a bit?
The tricky thing is that both the viaduct and the community path
have an elevation change along here, as you can see on Google Maps looking southwest. So you either need to have a convergence well to the
north of the "landing" or you need a convergence well to the
south.
Three alternatives plotted below:
Alt 1 (pink): surface streets, no eminent domain
Alt 2 (purple) surface, eminent domain clears buildings, grade crossing with community path at ground level
Alt 3 (orange) mostly elevated, diverging on the viaduct itself, maintaining elevation while Medford branch tracks & community path drop, in order to clear over the community path as soon as it reaches ground level
Alts 2 and 3 definitely are
better on the curves issue, and Alt 3 probably makes a noticeable difference in running time compared to Alt 1, but still is going to be a marked difference -- my rough estimate is that it only saves you about 700' of running track, so you're still looking at a 400% difference compared to running northbound.
How important is it to grade separate the community path from a single track LRT track?
Well, to a certain extent this will depend on whether the track is in regular revenue service. If it were used only during "special services", then maaaaaaaaybe you could possibly swing it? (Maybe particularly if it were a protected crossing with gates and everything.) But in every day revenue service, I think it'll be a non-starter. Too disruptive to path users, and likely enacting too severe a speed penalty on the trains (especially if the crossing isn't fully protected).
The other angle that we haven't talked about yet is train traffic. Looping around via the northwest quadrant means that the stretch of westbound track between the Sullivan/Lechmere divergence (between the viaduct and the community path in the lower right of the above image) and the divergence to Poplar St would see:
- all westbound Union/Porter trains
- all southbound Sullivan-Grand Junction trains
- all westbound Lechmere-Grand Junction trains
- all southbound Sullivan-Lechmere trains
Which pretty easily could become a bottleneck. To me that tips the scales in favor of doing something via New Washington St, which has a lot of the same drawbacks (including a similar running difference in northbound vs southbound), but which avoids the traffic.
I'll likely edit this to add comments on the larger post, but I wanted to acknowledge that I didn't get that's what the intention was. That'd be a good solution to avoid any unnecessary criticism (I'd go with bronze on account of it being a.) closer to brown than orange and b.) sounding better to me than copper, which doesn't quite roll off the tongue as nicely).
I myself am most intrigued by the sound of "the Chestnut Line", but I'm sure some market research would be revealing one way or another!
J is cut back to Boston University, with potential provisions for extension south depending on reliability
Is that tied into the Commonwealth line, or separated? If we're terminating the J at BU, it might be useful to have the ability for the trains to run to Kenmore. Probably not as a regular service pattern, but it might help dealing with, say, crowds from Sox games and such.
I haven't fully sketched out what I would do with this junction, so it's an open question.
F-Line did a design a while back, but his did not connect to a surface running route on Park Dr, and connected the Commonwealth Subway itself, which I'm suggesting is actually not vital.
Assuming a Commonwealth Subway is built (which I do recommend), my thinking would be to keep the surface tracks in place between Blandford Portal and BU Bridge (convert the ROW to support BRT as well), and use them as a non-revenue connection for equipment moves and special services to Kenmore as you mention. (Alternatively, you could look at a connection at the Fenway portal via
this parking lot, but I think the curve is too tight.)
Probably down to the map, and likely manageable (or else we'd have to reshuffle the colors...again), but in that image there's way too much similarity between magenta and red. If that were real-world some poor sods trying to go from Harvard to the Common would wind up at the cruise terminal. I suppose we could just put up signs that said "THIS ONE DOESN"T GO TO PARK STREET" kind of like those signs screaming at people to take anything but an "E" to get to Fenway on the GL.
Yeah, the colors are a pain, particularly on this map since I'm also competing with OpenStreetMap's color palette (ie. the yellows of major surface roads, the magentas of limited access highways, etc). This is also why the "Gold Line," as you mentioned, is a bit on the orange-ish side. I'm confident that we
can find hues of these colors that are distinguishable on a diagram, but likewise believe letters are probably the better solution long-term.
I like this idea. Any chance a Silver Line branch could take up any of the slack if Design Center can't quite swing 12 minute headways? Even that Aqua/Teal (I'm just calling it the Sharks line in my head) stop is pretty close that it'd be useful for anyone who doesn't need a direct Magenta ride.
Yeah for sure, I think there are options to supplement Design Center: Silver Line,
Navy Line (because it has so many water crossings and [could] serve the Navy Yard!
), and/or short-turn South Station-Design Center supplemental service.
It's not immediately clear to me from the map, but would a Gold-Green transfer have to happen at the GJ? It'd be a hell of a lot easier to site the station for it, but at the cost of losing the greater Union/Medford frequencies if the transfer was at Brickbottom. Obviously if "getting downtown" was the primary objective, a transfer to Orange at Sullivan would be better, but some Green transfers would still need to be provisioned for. (Also, now I'm noticing that the Gold and Orange look quite similar on the map, which will be funny when someone boards at Sullivan trying to get to the Bruins game and winds up watching the Terriers.)
You mean would it be possible to have a transfer station somewhere in this red circle? (To enable transfers between Gold and all three Green branches? Functionally equivalent to a transfer at Lechmere?)
I'm skeptical -- I think it's pretty likely that all of the grade changes would kill us here and make it difficult to site platforms on flat stretches that still are close enough to make for decent transfers.
This is the best I could come up with as a quick sketch:
The Gold Line line platform is a complete guess, but the idea is that whatever platforms it gets would have to be somewhere on that side of the junction -- whether an island platform or side platforms or whatever. Likewise, the southbound Green Line platform would need to be south of the Union-Medford merge, which means that it's at least 250' of walking between the platforms (plus a couple of grade changes).
So... maybe something could be done? But definitely a Project™ . (Also I'm looking now and the platforms I sketched above are way too short -- the Medford and Lechmere platforms could be extended, but the Union platform is very constrained.)
Like I mentioned previously, one way to offset would be to add a Sullivan Branch <> Union Branch Gold Line service, which should be very doable from a capacity perspective. Journeys between the Medford Branch and Sullivan Branch would still be inconvenient... I guess you could also leverage the yard leads going toward Medford, though that would probably end up using level crossings in the yard (and would make for a pretty useless U-shaped service).
This was one reason I was looking at a station at McGrath Highway. (I really need to start looking at that junction more carefully.) Looking back,
F-Line definitely thought it was possible fit a small station on the Grand Junction there, though I understand why
@The EGE is skeptical.
Maybe you do a Gold <> Union transfer at McGrath Hwy, and Gold <> Medford transfer at Brickbottom Junction. The viaduct for the Medford Branch is mostly level, so, maybe you could do it?