The Wrong Kind of Branching

Transit lines branch. Core routes have more demand than outlying ones, so naturally trains and buses run on trunk lines in the core and then branch farther out, to match frequency to demand. I gave an overview of this years ago. This is both normal across nearly all significant transit systems, and good practice. In this post, I’d like to focus on the opposite kind of branching, which I am going to call reverse branching, when one outlying line splits into two core routes. This is much less common, but exists in multiple cities, and leads to problems including restrictions on capacity and disappointing ridership. Cities should avoid building new lines that reverse branch, and in one famous existing case, London’s Northern line, the city is working on changing the situation by building a new outlying branch.

London’s Northern line, as can be seen on the Underground map, has three branches to the north and two in the center, but just one to the south. The highest ridership demand is in the center, but because both branches feed into just one southern branch, there is less than full capacity on the central branches, about 20 trains per hour each, compared with 30 tph on the southern branch and 33 tph on the Victoria and Jubilee lines. As a result, Transport for London has made recurrent plans to split the line for good: one central branch (through the City of London) using the existing southern branch and two of the northern ones, and one (through Charing Cross) using one northern branch and terminating at Kennington, the junction with the southern branch. An under-construction extension of the line from Kennington to Battersea can then be tied to the Charing Cross branch. There is some NIMBY opposition from a member of Parliament representing a constituency on one of the northern branches, who would like her constituents to have one-seat rides to both branches, but most likely, Transport for London’s need for capacity will make the split inevitable once the Battersea extension opens, ending the reverse branching practice.

In New York, routes branch and recombine, and thus it is common to have trains of different colors (which only denote Manhattan trunks) running together on a branch in Brooklyn, Queens, or the Bronx. The single busiest entry point into the Manhattan core is via 53rd Street Tunnel (connecting to Queens Boulevard), technically a branch since it runs trains connecting to both the Eighth and Sixth Avenue Lines. This, again, causes capacity problems. It’s not so bad on the numbered lines, where four trunk tracks (the Manhattan express trunks, carrying the 2/3 and 4/5) recombine in a different way to four tracks in Brooklyn (pairing the 2/5), but the lettered lines’ reverse branching in Uptown Manhattan and Queens initially forced eight trunk tracks (the Sixth and Eighth Avenue services, the B/D/F and A/C/E) to converge to six branch tracks (the two Queens Boulevard express tracks via 53rd, and the four Central Park West tracks). New subway connections have replaced this situation with twelve trunk tracks (including the Broadway Line’s N/Q/R) splitting to ten, spreading the problem around but not dealing with the fundamental restriction on capacity. The under-construction Second Avenue Subway will connect to the Broadway Line and run Q trains, raising the number of lettered tracks Uptown and in Queens to twelve, but this will not be enough to disentangle the tracks and provide full capacity on each core track; see below for proposed examples.

In Delhi, the Green Line splits into short branches, to provide transfers to two different Metro trunk lines. As seen on the system map, the Green Line does not enter central Delhi, and the current setup allows passengers to travel to central Delhi via two different routes. However, the Phase 4 extension plan extends the one branch to go out of the city in a V-shaped direction (the light green Kirti Nagar-Dwarka Section 28 line on this map), and has an extension that may connect to the other branch (Inderlok-Indraprastha, colored ocher on the map) to connect it to central Delhi, which may cause a serious mismatch in demand on the outlying common segment.

Finally, in Tokyo, subway lines reverse branch in two locations. The Namboku and Mita Lines share their southernmost three stations and the tracks in between. Although most Tokyo subway lines, including Namboku and Mita, run through to commuter lines, which provide the normal kind of branching, the Mita and Namboku Lines only do so either to the north or via the shared segment, as seen on this map, constraining capacity. They run only 12 peak tph each, and have low ridership by Tokyo subway standards. The Fukutoshin and Yurakucho Lines are in a similar situation, but the Fukutoshin Line does run through to a commuter line, the Tobu Tojo Line, without going through the shared segment (it is not depicted on the map, which is a few years out of date). The Fukutoshin Line has low ridership (see last page here), but the Yurakucho Line does not.

In all examples I’ve listed so far, the two core branches serve very central areas (as in London, New York, and Tokyo), or neither of them does (as in Delhi). Tokyo is somewhat of an exception, since the Yurakucho and Mita Lines serve Central Tokyo and the Fukutoshin and Namboku Lines serve secondary centers, but those secondary centers are very dense themselves; the Mita and Namboku Lines in particular are quite close in ridership. I am more wary of proposals to split an outlying line in the core that have one branch serving the CBD and one branch avoiding it, as in Delhi, assuming I understand the proposal correctly.

Also of note, all the examples I’ve listed involve subways. This is because conventional branching, with a core trunk splitting into multiple outlying branches, is more limited on urban rail than on both buses and regional rail. Most subway lines do not have more than two branches feeding into a trunk. In New York, not counting the split in the A, which is inherited from the LIRR, there is exactly one place where three subway routes share tracks: the N, Q, and R from Manhattan to Queens. In Stockholm, with its highly branched subway network, only one line, in one direction, splits into three. This is because even a split into three branches requires limiting off-peak frequency on the branches to less than a train every ten minutes, which is undesirable in large subway systems. The result is that reverse branching can easily create a situation in which there are more tracks in the core than in the outlying areas, as it does in all four cities surveyed above, restricting capacity on each core track.

In contrast, regional rail tends to operate at lower frequency on the branches, and this permits conventional branching with more than two branches per trunk. In addition, there are often turnback facilities at through-stations, and substantial four-track segments on otherwise two-track lines. The result is that reverse branching is possible without any constraint on core track capacity. The Berlin S-Bahn is highly branched in both the conventional and reverse senses. The RER E is being extended to the west, including a takeover of an RER A branch. And the Tokyo commuter rail network has extensive reverse branching, coming from through-service between commuter lines and subway lines but also from the Shonan-Shinjuku Line’s split from the Tokaido and Tohoku commuter lines. In none of these cases is there a significant restriction on core capacity, simply because there’s enough slack in the branches that they can’t fill to track capacity unless the core has filled as well.

In the US, I am familiar with three proposals for new subway lines that involve reverse splits, in Boston, Washington, and New York.

In Boston, the proposal actually involves commuter rail rather than the subway: the Worcester Line would use the Grand Junction Railroad to go through Cambridge to reach North Station, bypassing South Station. See map on page 38 of the statewide transportation capital budget proposal. This would not reduce capacity, since the Worcester Line is nowhere near exhausting the capacity of a two-track railroad, and moreover, the Grand Junction line would terminate at West Station within Boston proper, where there’s a railyard. However, this is still bad transit, for other reasons. West Station serves a residential neighborhood, without enough density to justify a fork toward both North Station and South Station. On top of that, since North Station lies outside the Boston CBD, the proposal is essentially a mixture of a radial and a circumferential line, with all the problems that would bring – and despite running as a circumferential line through Cambridge, there is no transfer planned with the Red Line, although the Grand Junction passes close to the Kendall/MIT station.

It would be better to bag all plans to use the Grand Junction until such time that the state builds the North-South Rail Link, connecting North Station with South Station. Then, the Grand Junction would make an almost perfect alignment for a circular line, with its eastern leg connecting North and South Stations and its western end going through Cambridge, making several stops, including a transfer to Kendall/MIT. This would require high investment – besides being a single-track at-grade line, the Grand Junction would require a new junction to connect to the Worcester Line to go east toward South Station, whereas today it only connects to the west, toward Allston and Brighton – but still a fraction of the cost of the North-South Rail Link, which is getting some serious political support, including from former governors Michael Dukakis and William Weld.

In Washington, there already is some reverse branching: the Yellow and Blue Lines share tracks in Virginia, but run on two different trunk lines in Washington proper, each shared with other lines, so four central tracks become four tracks in Virginia. But now with the opening of the Silver Line, raising the number of Virginia tracks to six, WMATA would like to separate the Blue Line from the Orange Line, which it shares tracks with in Washington, in order to provide six tracks across the District as well. This can only lead to awkward service patterns and wasted core capacity, as Matt Johnson demonstrates on Greater Greater Washington: because the Orange and Silver Line will keep interlining under any plan, reckoned from their split east there are only four tracks in Virginia and not six. Moreover, the Yellow Line interlines with the Green Line in the District, which means that even if it’s separated from the Blue Line, it could not run at full capacity.

Washington built itself into a corner with its Metro route decisions. There’s no corridor in the city that really needs a subway line; unlike New York, Los Angeles, and San Francisco, Washington has no corridor with so much bus ridership that it should be a subway line. A fourth subway line would be useful for service to Georgetown, but that’s about it. So decisions about a fourth line in the District should be based on the capacity needs of the branches, not those of the core. On a list of possible changes that WMATA looked at, Greater Greater Washington included a separated Silver Line, including separation up to the junction with the Orange Line so that they share no tracks. I’ll add that if WMATA wants to go down that route, then it should give the Orange Line its own route through the District and keep the Silver and Blue Lines together; this is because the Orange Line is the busiest of the three, so that it should be the least branched, in this case not branched at all whereas the other two do branch.

Finally, New York. Second Avenue Subway is going to change the nature of the reverse branching used by the lettered lines, for the better. Because the plan for Phases 1 and 2 is to run only the Q train, the city will finally have matching numbers of lettered tracks in and north and east of the Manhattan core: twelve tracks in the core, and twelve in Uptown Manhattan and Queens. Unfortunately, it is impossible to match service, because that would sever too many connections. Second Avenue Subway only connects to the Broadway express line, so to match service there couldn’t be any other service using the Broadway express.

Recall the London NIMBYism mentioned at the beginning of this post: that was about a service change that would give commuters a cross-platform (see comment with diagram) transfer between their branch of the Northern Line and the central segment of the other branch. In New York, the transfers in western Queens involve a lot of walking between platforms, if they even exist. Then all the Broadway locals (the N/R) would go to Queens through 60th Street Tunnel, and thence to the Astoria Line, severing the connection to the Queens Boulevard Line. The Queens Boulevard Line has two ways into Manhattan: 53rd Street, which connects to both Eighth and Sixth Avenues, and 63rd Street, which connects only to Sixth Avenue. Moreover, either all F trains (through 63rd) have to run express in Queens and all E trains local, or the reverse; mixing and matching would produce at-grade conflict at the junction, as seen on the Queens 1 track map on nycsubway.org. The transfer between the E and F would be located at 74th Street in Queens, several kilometers east of the split, which is located just to the east of the westernmost express/local station, Queens Plaza. Neither the E nor the F would have a transfer to the N/R near their respective intersection points. The Q would not have a transfer to the E (it would have one to the F, though). This puts many commuters in an impossible situation and the capacity gains from it are frankly not enough to be worth it.

Instead, the capacity gains would be limited to running some more express trains on the Broadway Line. Before the service cuts in 2010, the N ran express on the Broadway Line, the Q terminated at 57th Street at the north end of Midtown, and a fourth Broadway route, the W, ran local and served the Astoria Line. Once the Q is extended up Second Avenue, the restored W could beef up Broadway Line service. Second Avenue would only get a branch despite its high ridership, but it’s still only a segment of a line.

Then there are Phases 3 and 4 of Second Avenue Subway, serving Midtown and the Lower East Side, where the Q runs on Broadway. The official plan introduces another reverse branching: a new route, the T, is planned to run the entire length of Second Avenue: see map here. When both phases are complete, there will be fourteen lettered tracks in Midtown but only twelve Uptown and in Queens.

To resolve this, the MTA should activate a connection that is included in the Second Avenue Subway plan as a non-revenue connection: a connection from Second Avenue south of the Q/T split at 63rd Street to 63rd Street Tunnel; currently, 63rd Street is the least used connection from Manhattan to Queens, since the reverse branching limits capacity and 63rd Street is the least useful connection since it enters Manhattan north of Midtown. This implies there should be a Queens Boulevard-Second Avenue service, which I will call the U, one letter next to the T. The Queens Boulevard express tracks are filled to capacity and the local ones are not, so the T should run local, cutting the frequencies on the existing local R and M trains a bit to make room. It would still leave New York with twelve Uptown and Queens tracks diverging to fourteen Midtown tracks, but it would distribute the load better, in the same way the present system distributes the load better than the 1930s-era reverse branching from six to eight tracks did.

New York is in a somewhat special case, in that its subway system is based on heavy branching and reverse branching, and moreover it’s historically based on three different systems, with poor transfers between them. Fully untangling the lines after Second Avenue Subway’s Phases 1 and 2 are built is not possible because there are no transfers between the lines that would result, and the station placement is such that any new transfers would involve long walks between platforms.

Other cities, especially cities planning new systems from scratch, should not emulate this feature, and should instead design all lines to either not branch at all or only branch conventionally. A system designed from the ground up could have cross-platform transfers between lines, and even make sure they’re timed, reducing the cost to passengers of having to transfer in lieu of using a reverse branch. It could be coherent, in the sense of making it easy for an unfamiliar passenger to understand how to get from each station to each other station. And it could be built for maximum capacity in the most crowded segments, where it matters the most.

96 comments

  1. Matthew

    There’s the perennial proposal to put a Red Line branch under Mass Ave from Central to Andrew or thereabouts. That’s reverse branching, which is why I don’t think it’s a good idea, not to mention it’s probably ridiculously expensive.

    I think you discount West Station a bit too much. The area around the future station is being conceived as a site for intensive redevelopment (and I’m not talking about the Olympics). The Worcester line, once brought up to basic standards, will have more than enough capacity to branch, as you note. West Station itself will be four-tracked, we’ve made sure of that. There will be a station stop at Kendall Square, nobody is assuming otherwise right now. Yes, in the past, proposals to bring trains to North Station that way failed to include a stop at Kendall, and they were rightfully nixed.

    Although it’s a reverse branch, the Grand Junction serves a busy secondary CBD and the North Station area (which does have stuff) with access from the west much better than the existing transfer at South Station or Back Bay. It allows people to avoid the overloaded Park St / Downtown Crossing nexus. Allston itself also has the potential to become a tertiary CBD, with whatever Harvard manages to put up, plus the existing business district. West Station will also be fairly convenient to Harvard Square, and a natural stop for crosstown buses if MassDOT will allow that connection over the highway to be built (we’ll see).

    The Grand Junction’s main advantage is that it exists; therefore it can be improved with service through incremental investment. First you might stop a few commuter rail trains from Framingham/Worcester at Kendall on their way to North Station. Later, add passing tracks and start running all-day frequency with whatever equipment is available (maybe DMU). Then, figure out how to sort out the grade crossings and increase the frequency. Admittedly, on that last point, I’m not sure what the answer is. But I don’t anticipate this stuff to happen right away. It’s going to take time. Much like the redevelopment of Beacon Park. Eventually, we may get to the point where converting the Grand Junction to some kind of Urban Ring is the appropriate way to go, but that too is an incremental step.

    • Matthew

      Oh, and as good as the NSRL is, and as much as I like Dukakis, I just don’t see it happening within the next few decades. No matter how many articles get written about it. There’s just no appetite for that kind of investment and tremendous reform of commuter rail operation that it would demand.

    • Alon Levy

      At least on the map I saw, there’s a stop called Cambridge in what I presume is the Kendall Square area, but no direct transfer to the Red Line. Of course, current plans do not involve free transfers either way (where a bus-to-subway transfer would, which is another strike against mainline rail in Allston), but even signing the stations as one location and providing a clearly signed covered walkway would be tremendously helpful. I routinely use Porter to connect between the Red Line and the Fitchburg Line, even though I need to buy a separate ticket.

      I really don’t think Allston has the potential to become the region’s third CBD, if that’s what you mean. There are a lot of jobs at Harvard, Kendall, and Central Squares. Metrotown generates 26,000 SkyTrain boardings and Patterson another 5,000: a bit more than Harvard, but way less than the combined total of the Back Bay stations (Back Bay, Mass Ave, Arlington, Copley, Hynes, Prudential). That’s the scale of what’s required. Nothing less could justify a three-station shuttle whose other stops are not the CBD, and even then it’d be pretty questionable. Adding more stops farther out is possible, but that makes the line radial-circumferential again. People in Brighton would be a lot less interested in a connection to Kendall Square and North Station than in one to Back Bay and South Station.

      Another issue, which I did not bring up in the post but I think matters here: reverse branching is like express service on a two-track line, in that it works best at medium frequency. At high frequency, it creates capacity bottlenecks, so pretty much every time you think you’ll run more than about 12 tph on each central trunk, you shouldn’t do it. At low frequency, it splits frequency. In other words, let’s assume the Worcester Line runs 2 tph all day. There’s a proposal for another 2 tph, from West Station to either North Station or South Station. The South Station option is much better, because that gives 4 tph between South Station and West Station, which allows enough frequency that people could take the train without planning their entire lives around it, and that walking to the station without consulting a schedule would beat the Green Line. Even at 3 tph I think beefing the frequency would be the better option, but that requires a bit of a think. At 4 tph, the new service becomes more interesting.

      • Matthew

        Unfortunately I don’t think it’s possible to have a quick transfer between the grand junction and the red line. Some walking required.

        Allston wouldn’t be the third CBD, it would be a tertiary level district. Back bay, Longwood, Kendall are all bigger. However, Harvard’s expansion knits Harvard square and a potential West station much closer, for better or for worse.

        A grand junction line does not preclude improved frequencies to South Station. I anticipate that frequent service to Back bay and downtown will continue to be the main use of the line. We’ve been pushing for at least 4 tph to South Station in the eventual service plan; that can be augmented by 4 tph eventually to North Station when feasible. Some trips would probably stop in Brighton, others continue west to Newton or beyond.

        • Alon Levy

          Honestly, if you can actually get 4 tph all day, then tip of the hat to you. For now the Fairmount Line plan is 1.5 tph, but maybe Allston has enough political pull to get usable frequency.

    • betamagellan

      Although it’s a reverse branch, the Grand Junction serves a busy secondary CBD and the North Station area (which does have stuff) with access from the west much better than the existing transfer at South Station or Back Bay. It allows people to avoid the overloaded Park St / Downtown Crossing nexus.

      Secondary CBD = Various BU sports venues?

      Even under the “DMUs Everywhere!” plan frequencies are going to be lower than the current alternative to avoiding Park Street—the bus, which, given the ridership on the Mass and Harvard Ave. lines, is not exactly unpopular (and has the benefit of operating outside FRA jurisdiction), currently operates at higher frequencies, and has the benefit of being a more direct connection between more origins and destinations in Cambridge and Boston.

      Although to be fair the version of the plan I’ve seen doesn’t involve splitting off Worcester and has the Cambridge-Grand Junction as a shuttle service between North Station and Grand Junction, though obviously the budget proposal implies differently.

        • threestationsquare

          Is it really accurate to call that branching then? The frequency of the Grand Junction shuttle could be unrelated to (and potentially much higher than) the frequency west of West Station. This seems almost like calling Newark PATH a “reverse branch” of the NEC (or even calling the E train a reverse branch of the LIRR); it serves a different market and happens to end at a transfer station. Whether that market is worth serving is a different question.

        • betamagellan

          Ahh, didn’t bother reading it—I just assumed the old “Let’s send some Worcester trains to North Station because we can!” proposals from a few years back had been resurrected.

  2. R. W. Rynerson

    Denver’s light rail network includes reverse branching, with major sports venues and a growing business/residential district on the weaker branch. Ever since the 2006 opening of the Southeast lines, RTD has used timed-transfers of various sorts to ameliorate the complications. Due to the budget roller-coaster driven by the Great Recession, there have been more changes than is desirable, but timed-transfers — where feasible — keep popping up.

    The “where feasible” part means using infrastructure imaginatively, because funding processes resist providing infrastructure for service evolution. After I realized how complex our LRT net was going to be, I examined the Berlin S-Bahn in 2005 and copied as many of their ideas as we could. It’s hard to match their legacy turnback tracks or cross-platform layouts, but as RTD has matured, there has been a growing recognition that “value engineering” needs to take rolling stock and operating costs into account, warranting some infrastructure expenditures.

    Video of a Denver timed transfer and related connections: http://youtu.be/2f8VBuSzv5g This is mainly Hnb>Dsb and EsbDsb. Working right, it leaves the platforms almost empty (a lone walk-in waits toward the end of the clip).

    At night, transferring passengers move slowly, for reasons including intoxication and their surprise at finding their connection waiting. Due to the night-life and sports venues, many of these customers are not commuters. I have met people who were traveling based on information from friends who had told them they would have a long wait, so they could not believe that the big white thing across the platform was their connection.

  3. betamagellan

    I think the Washington Orange Line’s higher ridership is more a function of it service to the Fairfax-Clarendon subway—I’m guessing the highway-running stretch alone doesn’t have much to support it if it were rerouted onto expressway ROW to go into Georgetown, whereas the Silver Line would still have an anchor at Tyson’s to drive ridership past Arlington.

    I’m also guessing Arlington-to-Alexandria are a big motivation for a separate Blue Line, and IIRC there was some study of the feasibility of a wye south of Rosslyn, with the intention of alleviating the Blue Crush by splitting Blue into DC- and Arlington- branches

  4. threestationsquare

    Regarding London: My understanding is that the obstacle to splitting the Northern Line is not Kennington (which already has a segregated turnback loop for Charing Cross trains with only some peak trains continuing south to Morden) but Camden Town and its junction. Contrary to what you say, the transfer there is NOT cross-platform (see this track map or this drawing) but requires the use of narrow passageways within the station, which don’t have the capacity for the number of passengers who would need to transfer if each northern branch were permanently paired with a central branch. This means that before the Northern Line can be divided into two separate lines, Camden Town station must be expanded/rebuilt, but as an extremely busy deep underground station this is a very difficult and expensive project and still a long ways off (further in the future than the Battersea branch at any rate).

    In the meantime, capacity on the two central branches of the Northern Line has recently been increased to 24 tph. A recent post at London Reconnections has good discussion of this and future developments.

    A discussion of reverse-branching in Central London should probably also mention the mess that is the District line.

    (Incidentally I’ve gotten the impression that the Battersea Northern Line extension is to a significant degree Development-Oriented Transit pushed by the Mayor without due consideration given to alternatives, though not as bad as e.g. the 7 extension.)

    • Alon Levy

      The subsurface lines in London are quite regional rail-like in how many outlying branches serve each central trunk. This lets the District Line get away with what it does: the Edgware reverse branch is matched to the Wimbledon branch. At least in the off-peak, both the District and the Metropolitan trunk get 24 tph (link), including Circle and Hammersmith and City interlining.

  5. jefftk

    “Most subway lines do not have more than two branches feeding into a trunk. In New York, not counting the split in the A, which is inherited from the LIRR, there is exactly one place where three subway routes share tracks: the N, Q, and R from Manhattan to Queens. In Stockholm, with its highly branched subway network, only one line, in one direction, splits into three. This is because even a split into three branches requires limiting off-peak frequency on the branches to less than a train every ten minutes, which is undesirable in large subway systems.”

    Boston’s Green Line is an interesting comparison here. From Copley inward you have four branches (b, c, d, e) sharing a pair of tracks, with posted rush hour frequencies of 7min, 6min, 7min, 6min respectively, for ~37tph. Now, this isn’t a standard subway and is sight signaled, so normal headway rules are out the window, and often it goes really badly with horrible bunching and delays, but when it works well the frequency they’re maintaining on branch lines is comparable to the Orange Line (6min) which has no branches.

    • Alon Levy

      Boston’s Green Line is subway-surface, and these tend to be highly branched, because the capacity on the central subway segment is much higher than on the outlying light rail branches. The same is true on Muni Metro and the SEPTA Subway-Surface Lines.

      • jefftk

        I just looked at the frequencies of these lines for the MBTA, MUNI, and SEPTA, and they’re remarkably high. At peak SEPTA seems to be running 70tph on the subway portion! [1] With a capacity of 70tph on a shared track you could have ~6 branches and maintain reasonable service levels.

        There’s something I really don’t understand about safe train movement here: why can the trolleys manage these extremely low headways but subways generally max out around 30tph? Is it that they’re light so it’s not too dangerous to operate them on sight?

        [1] http://www.jefftk.com/p/subway-surface-frequency

        • threestationsquare

          In 1911 there were 211 streetcars turning around at Boston’s Park St station in the evening peak hour, and another 105 running through. (Though I’m not sure if some of those were possibly coupled into two or three car trains.)

        • anonymouse

          Among other things, a trolley is also much smaller, and clears platforms and junctions faster. They also, as mentioned in that link, can easily double-berth in stations.

        • Henry

          Headways are dictated by safe braking distances. Subway trainsets are generally heavier in absolute terms and also move faster, so their braking distance has to be managed by block signalling due to the greater distance it takes for them to stop.

          • anonymouse

            Streetcars also tend to have track brakes, which allow them to stop much, much faster than subway trains, since they’re not limited by adhesion.

    • knott

      As a person who thinks branching is a very good thing I don’t think that 3 branches is a problem for a dual-track underground subway system.

      The central segment should be able to handle 5 trains / 10 minutes, that should mean that a branch could maintain 3-4 minutes/branch during rush-hour, and 8-10 minutes off-peak. That seems acceptable for a branch everywhere except the most used branches in in the most central and dense parts of a very big city (and in these cases a separate nearby line is probably anyway a wise investment). In the likely case that one of the branches is less densely populated it could also serve somewhat fewer trains than the other branches.

      Instead of seeing branches as a problem, I would see it as good industry practice. The main trade-off with branching is that it increases infrastructure costs (more tracks/tunnels and stations) while being economic in terms of service levels. In the long term costs for service levels will almost certainly be more important than additional up-front capital investments. In developing countries with huge underserved demand it might perhaps be wiser to invest in high capacity non-branched options, but this is virtually never the case in developed cities.

      • Dave

        What happens when 1 branch becomes more popular relative to the other one(s) (either because the stations on the popular branch gain a lot of development around them or because the other branches lose all their ridership)? Branching REQUIRES each branch to have headways that are multiples of the other ones… so you can run Branch A and B at the same headway, or Branch A at double the headway of Branch B or Branch A at triple the headway of Branch B or so forth. But Branch A might actually need only 1.5x or 2.4x or 3.7x the service of Branch B, which means you end up underserving Branch A or overserving Branch B to get nice integer multiples. (The math gets worse with a 3rd and subsequent branch.) THIS IS THE PROBLEM WITH BRANCHING… you’re locking into place the choice to operate all branches as multiples of each other FOREVER… which means you’re predetermining how popular each branch can possibly be relative to the others.

        • Dave

          http://www.humantransit.org/2011/02/basics-branching-or-how-transit-is-like-a-river.html for another opinion of how branching permanently compromises the future growth of your transit system. Branching should be discouraged, unless you *know for sure* that none of the branches will develop differently from all the others. (Note that branches frequently become part of the CBD or a new CBD in and of themselves… and then you have to do what London is doing now – at great expense! – with the Northern Line to remedy the situation.)

          • Alon Levy

            Do branches ever become part of the CBD? The Northern line is not a conventionally branched network that became reverse-branched due to subsequent growth. No: Bank is where London’s center has been since London was founded, and Charing Cross was in a commercial part of Westminster even then. These were two separate lines that the London Underground decided later to operate as one system.

            Well, in Stockholm there’s Kista, which is on a branch, but the very existence of Kista is a failure of urban planning regardless of how the subway network looks. But most of the busiest subway stations are not on branches (see map on p. 11 here) – Kista and my home station, Tekniska Högskolan, are the major exceptions. And of those, Tekniska Högskolan is a transfer station to a narrow-gauge railroad that should have just been regauged and turned into a Metropolitan line-like branching of the Red Line.

            But in general, CBDs stay in place, and have way more demand than outlying areas. When there are new edge cities, they create problems for rapid transit networks, with or without branching. The Paris Metro barely branches, and still had to be extended to serve La Defense. The RER is highly branched, but La Defense is still on the trunk, and still the region is spending money on extending more lines there because of all the travel demand.

          • knott

            I don’t really see the problem. With 12 trains every 20 minutes you could run them as 1-1-10, 1-2-9, 2-2-8, 2-3-7, 3-3-6, 3-4-5, and 4-4-4. Seems flexible enough for me, and there is of course even more flexibility than this example shows if you stray from the 12/20 formula. I think you are creating problems where there are none. (The Millbrae-SFO situation is of course awful, but that has little to do with the issues in this thread). And this is ignoring the obvious point that you can debranch the trains later on, build new lines to add capacity nearby, or add additional capacity at the central part of the branched line. Even if you add four-tracks in the central segment, that is still more economical than 3 different self-contained lines.

            Brand new lines in developed countries that suffer from capacity issues at the end of the lines is not really a problem in developed countries, our car oriented cities (even in Europe) simply don’t sustain that amount of heavy transit usage outside the immediate city center (look at the frequencies of the BART). To then add needless extra capacity in the center by refusing to branch is simply hard to afford. Branching is a great solution to the obvious problem that cities are dense in the middle, and less dense further out. Roads and legacy commercial rail systems are very branched for good reasons.

  6. threestationsquare

    Regarding New York: I’m not sure what at-grade conflict on Queens Blvd you’re referring to. Looking at the track map, QB local trains from 53rd St (like the M today) move to the local tracks just east of Queens Plaza (with the equivalent move for trains in the opposite direction just west of Queens Plaza), so both the local and express tracks have a single service on them (notionally half their capacity) when they reach 36th St junction. The 63rd St tunnel tracks connect directly to both the QB local and QB express tracks at 36th St St junction, and should be able to merge into each respectively just fine. This corresponds exactly to the situation immediately south of Columbus Circle, where the tracks carrying the D and B split to merge with the A and C respectively.

    The fact that the E and F (or equivalent lines) don’t have a transfer east of 74th St is unfortunate but note that E passengers can reach 6th Ave via the cross-platform transfer to the B/D at 7th Ave, so it’s only really a problem for F passengers trying to reach 8th Ave.

    I think it is possible to untangle the service patterns after SAS Phase 1 opens, and would propose the following service pattern:
    8th Ave local: All trains start from WTC. Half to CPW local (like current C) and half to 53rd St and QB express (current E).
    8th Ave express: All trains come from Fulton/Brooklyn. Half to CPW express (current A) and half to 53rd St and QB local.
    Broadway local: All to 60th St and Astoria.
    Broadway express: All to 2nd Ave (proposed Q). Passengers can reach QB via cross-platform transfer at 63rd & Lex.
    6th Ave local: Half to 63rd St and QB express (current F), half to 63rd St and QB local.
    6th Ave express: Half to CPW express (current D), half to CPW local (current B).

    The biggest drawback here is making it harder to get from Queens Blvd to the downtown Lexington Ave line (since the transfer at 53rd involves a longer walk than 59th and lacks express service) but I think that’s worth the increased capacity.

    It’s less obvious what to do once Phase 3 opens, will depend on what demand patterns are like then.

    • threestationsquare

      Also, I recall that your New York regional rail plan involved reverse branching on both the Hudson and New Haven lines. As you note, this works better on regional rail than on subways. But do you propose running lots of near-empty trains to Croton-Harmon and Stamford to ensure adequate off-peak service in the Bronx, or turning back a lot of trains at the merge points (Spuyten Duyvil and New Rochelle), or what?

      • Alon Levy

        Good question! My thinking on this has evolved, which is for example why my color scheme is exclusively by central track in this plan, whereas in my original TTP posts it was by branch: see maps here and here – and originally it was even worse, because both lines using the Hudson Line were the same color until Yonah made me change them.

        The answer on the New Haven Line is the simplest. There’s only capacity for about 6 local tph via what my plan that you link to calls Line 1, because of interference with intercity trains (but if there were capacity for more, then those trains should short-turn at New Rochelle). Add in 18 tph via the existing route to Grand Central, plus 6 tph on the existing Hudson Line route to provide some service to the stations in the Bronx, and this is already 24 tph on Line 2. Current traffic on the New Haven Line is already 20 tph, and this doesn’t include any local service on the NEC mainline south of New Rochelle, so 24 tph isn’t overserving it.

        The Hudson Line is the most complicated, because there’s nothing else that can add to its trunk service; hence the kludge with the Raritan Valley Line on my TTP plan, which assumed away railroad junction difficulties. Demand on the Hudson Line isn’t enough to fill a trunk line, even without reverse branching. Current peak traffic is 15 tph, but Yonkers is seriously underserved, especially at its local stations, because of low frequency and high fares; uniquely in Westchester, Yonkers’ inbound Metro-North traffic is far lower than its number of Manhattan-bound commuters. So this suggests the 6 Line 2 tph should run all day to Yonkers or even Greystone, and then Line 3 should get as much traffic as there’s demand for. 18 tph peak (not counting Line 2) is aspirational; 12 peak, 6 off-peak, with some kind of timed transfer to let Yonkers local riders transfer to express trains to Penn, is well within what can be filled if trains serve Yonkers better.

        • threestationsquare

          “There’s only capacity for about 6 local tph via what my plan that you link to calls Line 1” I assume that’s 6 local tph via Hell Gate, with additional trains (another 4-6 tph?) to Flushing and Port Washington?

          Only having 12tph peak / 6tph off-peak on Line 3 sounds potentially inadequate for Jamaica-Penn Station service? I realise that would be supplemented by some ESA-bound trains with timed transfers at Sunnyside to Line 1, but as you noted Line 1’s frequency is also limited, and in a future with integrated intracity fares demand to Jamaica is surely huge.

          • Alon Levy

            That’s 6 local tph via Hell Gate, and something on the order of 12 tph peak, 6 off-peak on the Port Washington Branch. Current PW traffic is 7 tph peak, but because it’s short and serves a major secondary CBD, the PW Branch’s ridership is more suppressed than that of the other lines. They’d meet ESA-bound trains from Jamaica and points east. Long-term it’s possible to even run 12 tph local via Hell Gate, if everything on the line except the bridge itself is four-tracked, but that creates a capacity bottleneck in the East River Tunnels, one that comes from conventional rather than reverse branching.

            With Line 3, Jamaica-Penn has a lot demand even with the ESA transfers; if Yonkers-Penn doesn’t pick up the slack, then some trains could short-turn at Penn. Because of West Side Yard, it’s possible for trains using the northern pair of East River Tunnels to turn without interfering with through-trains.

          • threestationsquare

            But isn’t turning trains at Penn (and the need to make sure they’re empty first) the Root Of All Platform Capacity Problems, which is why we need to accept through-running as our lord and saviour? Also, with appropriate station locations there would probably be a lot of demand along the Manhattan part of Line 3 (since with integrated fares it would provide a very attractive alternative to the 1 train) which would argue for turning trains at Inwood or Spuyten Duyvil. (Will the rebuilt Spuyten Duyvil bridge still need to be opened nontrivially often?)

          • Alon Levy

            It depends on how often trains turn at Penn. An additional 6 tph turning and going back east immediately is not as big a deal as nearly 40 tph going to the yard with many just sitting there until the PM rush.

            Inwood as a location for turnbacks is interesting. I don’t know if there’s enough space there to have trains turn; I think there’s only space for two tracks, but I could be wrong. A realigned Spuyten Duyvil stop, north of the junction with the current Hudson Line, might be better – it would require a small amount of landfill, though. I think the anchor is still Yonkers, and no place in Manhattan – the Inwood stop is on the wrong side of the Henry Hudson Parkway, and the 125th Street stop is sandwiched between the Henry Hudson and the elevated Riverside Drive, so these aren’t likely to produce so much ridership as to justify an additional 6 tph just for themselves.

          • threestationsquare

            I think stations at 125th and 155th would attract a lot of ridership; less sure about 181st and Dyckman given the difficulty of access. It looks like there is some room for extra tracks just north of Dyckman and you might get away with some small takings from the park as well. Historically (1871-1916) local Hudson River Railroad trains turned back at Spuyten Duyvil, at a track and station that formed a third, southern side of the wye just north of the bridge (empty land today). But I guess there’s plenty of track capacity from there to Yonkers and it takes less than 10 minutes so just running everything to Yonkers is probably fine.

          • Adirondacker12800

            If I remember correctly 155th would be useful for young athletic mountain goats. Upstate, anything north of 86th Street, is like that, unflat. There isn’t a whole lot of anything at 155th. 178th with the cross town buses, the vestigial PABT and a frequent shuttles to Columbia Presbyterian might be more useful

          • Adirondacker12800

            ti’s a lot cheaper to run them empty a few blocks and have them sit there until the evening rush than to run them empty to Morrisville. Bay Head and Suffern. have them sit around all day until the evening rush and then run them empty back to Manhattan. And they even found people to pay them to use the empty space above it. Probably not as much as they could have demanded but they got people to buy the air over it.

          • threestationsquare

            @Adirondacker12800: At 155th the tracks are right next some dense housing; just put in an elevator down from Riverside Drive. But at 178th the tracks are a long way from the bus station and anything else; the best option in the area is probably to build a long footbridge from the end of 181st St over the Parkway, and possibly extend the crosstown buses west on 181st. That or just run trains nonstop 155th to Dyckman.

            How much cheaper is it to short-turn trains at Penn than to run them through to Dover or Bay Head? It would be nice to see actual numbers on this. You’re paying the driver and conductor for a full shift either way right?

          • Adirondacker12800

            Just because the tracks are near dense housing doesn’t mean anyone in the suburbs wants to get on and off there or that significant numbers of the people living there want to loiter around waiting for a train when they can get on the subway and get where they want to go quicker.
            There are destinations at 178th that the buses can connect to. Shuttles for the thousands of people who work at the hospital for instance.

          • Adirondacker12800

            Electricity costs money. Wear and tear on the trains adds up. Eventually the day winds down and the trains have to be parked somewhere because if it make little sense to be running them empty during the day it makes even less sense to be running them empty overnight. NJtransit’s long range plans is to use the land out in the swamps just west of New York, that nobody wants because it’s filled in swamp contaminated with industrial waste, to store trains.

          • Alon Levy

            Actually, there’s a very good reason for nighttime shutdowns: routine track maintenance. In contrast, once the maintenance window is there, there’s no reason not to run trains. The trains already need to be bought for the peak, and the marginal crew salaries are lower off-peak as well because more off-peak service means fewer split shifts.

          • threestationsquare

            The 1 train takes 25 minutes from 157th to Penn Station, Alon’s Line 3 would get there in less than 15. And run at least 12 trains per hour all day. It would be the quicker way to anywhere south of 42nd St.

            And yes, I know running trains off-peak isn’t free. But given that the Japanese and European operators consistently do it (and manage to do much better financially than US commuter railroads) it evidently isn’t that expensive. Do you have numbers?

          • Adirondacker12800

            If you are going to Columbus Circle it’s faster than going to Penn Station on a train that comes through every half hour. Or Grand Central. Or Union Square. Or the World Trade Center. Or.

          • threestationsquare

            The proposal isn’t for some twice-an-hour joke, it’s for 12+ tph. Columbus Circle would still be faster via the 1 subway, but the rest would be faster taking an RER train and changing at Penn.

          • Adirondacker12800

            The official Metro North proposal is for four an hour peak. Someday.

          • threestationsquare

            Yeah, the Metro North proposal would not get significant ridership at the Manhattan stations (it also lacks fare integration). Alon’s regional rail proposal would.

          • Adirondacker12800

            No it wouldn’t. The people who live there and the people who visit there now … do it now.

            http://web.mta.info/nyct/facts/ridership/ridership_sub.htm

            Almost none of them are going to Penn Station. It takes time to get to the station. It takes time to wait for the train. It takes time to get off the train in Penn Station. It takes time to get to the subway so you can wait for the train to get you to Union Square or Columbus Circle or Grand Central or Wall Street or Brooklyn. It take time for the subway to ferry you from Penn Station to your final destination. For most of them just getting on the subway is a better choice.

          • Alon Levy

            Well, yes, but Inwood has long commutes, even with the A express. Each of the Dyckman Street subway stations gets 6,500 weekday riders, i.e. near the top end by the standards of commuter rail ridership.

          • threestationsquare

            It takes time to walk to the subway station and wait for the train there too. Today on the subway many people transfer to or from express trains to save time over slower one-seat rides, why would this be any different? The user experience would be indistinguishable from an express subway line (except perhaps for a few more seats and less standing room on the trains), it would get ridership like an express subway line. It’s the same as people choosing between the RER and the metro at Vincennes, or between the S-Bahn and U-Bahn at Spandau, or between the Underground and National Rail at Watford.

          • Adirondacker12800

            The RER goes someplace other than Les Halles and the U bahn goes someplace other than Alexanderplatz. There’s not a whole lot of people at 155th, most of them can get to a subway station faster than they can get to the river bank and very few of them want to go to Madison Square Garden on a given day.

        • Adirondacker12800

          6 trains to Penn Station means there are people changing trains in Stamford or New Rochelle every ten minutes during peak. That’s very very good for suburban service.

    • Alon Levy

      Yeah, this is what I get for not reading the track diagram carefully enough. Mea culpa. For some reason I thought the switches allowing the F to access the local tracks were the same ones used by the E.

    • Henry

      The 63 St-Phase 3 connection is only really useful if a QB Bypass is built, given that until then it’s just how you want to shuffle trains around on Queens Blvd. Most likely what will happen if the bypass is built and the Phase 3 connection is used is that the F will be rerouted to use express tracks to 179 St and an SAS service will use 63 St and the bypass to Forest Hills, making local stops east to 179 St.

      • Alon Levy

        What I think the bypass should be used for is a new branch going under Northern to Flushing, but the construction around the E/F segment under Northern might be gnarly. A QB bypass is less useful – QB is extremely crowded, but there’s a railroad parallel to it. Northern is vaguely parallel to the Port Washington Branch, but they’re not as close – the 7 is in between, for one.

        • Adirondacker12800

          that wouldn’t be a bypass that would be a new branch to Flushing.
          The bypass. in the iterations I vaguely remember, used LIRR row for two tracks of subway. Local from Valley Stream-ish to Jamaica, non stop to Manhattan on the LIRR ROW. I don’t remember whether it ran local or express in Manhattan. I don’t remember if there was a super-express/express/local transfer in Forest Hills. They would have to build another set of tunnels like the ones, in Queens, for East Side Access, for the super express. Tunneling under or elevating over the LIRR would be much easier and cheaper if there isn’t at grade ROW available on the LIRR. It sucks up the underutilization.

          • Henry

            The Bypass needs two sets of tunnels, but mostly just to connect between Forest Hills and Rego Park as shown in the track diagram here. There is room for six tracks in the ROW between Sunnyside and Rego Park where the Rockaway Beach Branch split off, and Port Washington trains could easily be shoved onto the four existing Main Line tracks, so voila, easy-to-build pair of tracks for the subway.

          • Adirondacker12800

            Not if they are running 20 trains an hour to Grand Central and 35 trains an hour to Penn Station and want to wedge 6 Amtrak trains into it along with 6 Metro North New Haven line trains.

          • Henry

            Then the bottleneck is at the East River Tunnels – all the tracks have to merge into four tubes anyways, and the extra two tracks on the PW are not going to provide additional capacity into Penn Station.

          • Adirondacker12800

            It has six or more tracks between Hunterspoint Ave. and just east of Woodside where the Port Washington branch diverges. The track maps I looked at are not current. They don’t have anything for East Side Access.

        • Henry

          The railroad parallel to it is also fairly crowded (assuming we don’t shove Overground-style mainline rail carriages with longitudinal seating onto the LIRR anytime soon), and on top of that has space for six tracks when the existing system could easily be handled by four.

          I don’t know if Northern Blvd’s construction costs would justify building a train line there, over building the bypass out to Forest Hills, or even a connection to take over the Port Washington Line, both of which are significantly easier. If you look at parallel bus routes, PW’s bus line, the Q58, is much busier and more crowded than the Q66 on Northern.

          From a “future expansion” point of view, the Bypass is also more useful; if the F is using the express tracks, that makes extension out to Springfield much easier without running into Marchetti’s constant of the one-hour commute. You could sink more money into extending a Northern line past Flushing, but you could also do that with the 7 or via an upgrade of Port Washington services.

          • Alon Levy

            The point is not to provide service east of Flushing; it’s to serve underserved areas north of the 7 and also build a second line to Flushing (or third, counting the PW line).

        • nei

          Couldn’t a Northern Blvd line be a branch of the local Queen Blvd line east of the Northern Blvd station? The local lines aren’t at capacity, and as long as the stop spacing isn’t too narrow the speed would be ok

  7. orulz

    In Tokyo the Yurakucho/Fukutoshin interlining is really not an issue since there is no bottleneck. You can think of the Seibu Ikebukuro line, Tobu Tojo line, Yurakucho Line, and Fukutoshin Line as basically a single eight-track corridor inbound to Ikebukuro. Four of the tracks terminate at Ikebukuro and four of them proceed through Ikebukuro, splittling shortly thereafter into the Fukutoshin line and Ikebukuro line.

    Hope this ascii art comes out.

    ----------------------------\
    TOBU-----------------------\ \
    TOJO-------------\ | | /--------------
    ----------------\ \ T T / /--YURAKUCHO--
    \ \------+=========+-------/ /
    YURAKUCHO/ \-------|IKEBUKURO|--------/
    FUKUTOSHIN /-------| STATION |--------\
    / /------+=========+-------\ \
    ----------------/ / T T \ \--FUKUTOSHIN-
    SEIBU------------/ | | \--------------
    IKEBUKURO-----------------------/ /
    ---------------------------------/

    The Mita and Nanboku lines are definitely wasting core capacity. Since the lines cross each other near the Tokyo Dome, I wonder if some benefit could be gained by connecting the lines at the southern end north of Shirokanetakanawa and on the north near the Tokyo Dome using the excess core capacity to create a new loop line. It is a bit of an oblong shape so not ideal for a loop line, but then again so is the Yamanote line, and it would turn some rides requiring a transfer into a direct ride.

    Interestingly, building connections and using the excess capacity you mention on the new Blue line and on the existing yellow line bridge for a loop is one of the things that WMATA Metro is considering.

  8. orulz

    Trying again with the ASCII art.

    ----------------------------\
    TOBU-----------------------\ \
    TOJO-------------\         | |                /--------------
    ----------------\ \        T T               / /--YURAKUCHO--
                     \ \------+=========+-------/ /
          YURAKUCHO/  \-------|IKEBUKURO|--------/
          FUKUTOSHIN  /-------| STATION |--------\
                     / /------+=========+-------\ \
    ----------------/ /              T T         \ \--FUKUTOSHIN-
    SEIBU------------/               | |          \--------------
    IKEBUKURO-----------------------/ /
    ---------------------------------/

    • Andrew in Ezo

      Some clarification perhaps, the actual junction is at Kotake Mukaihara, rather than Ikebukuro, though the various lines do serve Ikebukuro directly. Kotake Mukaihara is a bottleneck, as there is a flat junction where the trains from the various lines crossover (Fukutoshin Line run-through trains either to the Tobu Tojo Line or Seibu Ikebukuro Line, and Yurakucho Line trains similarly to the Tobu and Seibu Lines). This flat junction wreaks havoc whenever there is a service disruption, and Tokyo Metro is currently rebuilding the station track approaches to eliminate it.

  9. Ben Ross

    Full separation of Orange and Silver Lines is an integral component of WMATA’s core capacity plan , or at least it was in the presentation I heard a while ago. Silver Line will express parallel to Orange Line and then share new tunnel with Blue Line. The Silver Line separation is in a second phase because less urgent.

    • Alon Levy

      Well, as long as there is enough capacity in Virginia to make sure each of the three non-Red trunks through the District could run a full capacity’s worth of trains, it’s fine. Hence my fondness for separating the Orange Line from the Blue and Silver Lines (regardless of which of the two systems gets to go to Georgetown). Ordinarily I’d say the Silver Line express plan is a waste of money since local service is more important than saving airport riders a few minutes, but in this case, but the assumption of this separation plan is that the Orange Line would run 26 tph from Vienna to at least as far east as Stadium/Armory, so the Silver Line express plan becomes a capacity improvement.

      • johndmuller

        I like a Silver/Orange variation in Virginia where the lines are split just before Ballston to take their separate paths into the District. The new route would continue along (probably under) I-66 a bit longer, maybe with a new station on Lee Highway, then continuing down under Spout Run and the Potomac to come in under Georgetown. The existing shared section would be 4-tracked and the station in the middle (East Falls Church) would be a transfer station.

        This design (assuming the appropriate switching options were present) would open up the possibility of there being two Orange and two Silver lines, taking the two different routes in the District, like the IRT lines in Brooklyn give riders the choice between east and west side lines in Manhattan. This would apply to any other design as well, no matter where the crossing is, so long as the Orange and Silver retained enough contact to interline or at least allow transfers before going into the District.

        This brings up the question of where else besides Georgetown is the new line going to go in the District. This is a non-trivial question because if the alternate route is not very attractive, people will continue to use or switch to the old route with the embarrassing result of packed trains on the old route and relatively empty trains on the new. If the new route through the District is deemed less desirable, that would be an argument for combining it with (at least the majority of) the Blue line to free up the old route. If the Blue was also going to take the new route, it might be better to move the new crossing closer to Roslyn, although I think that it would be much more expensive.

        Insofar as the new route is quicker, that time saving could mitigate the effects of somewhat less desirable destinations. M Street across to Massachusetts Avenue then on to Union station is a somewhat reasonable route, although transfers to other lines would be necessary for more people than the old route pending considerable TOD along the new route.

        Interestingly, this route could be paired with a similar new Yellow line route in SW and SE DC, also through less fruitful territory to meet at Union Station – merging the Silver and Yellow lines into one VA-DC-VA routing and also freeing up the Yellow and Green Lines from each other. A new Yellow/Green transfer station, or sharing (and 4-tracking) the Green line’s Maine Avenue stations would also allow these riders choices of two different routes through the District.

        To further embellish this plan, the Yellow and Green could also each be divided into 2 sub-lines as in the Orange-Silver combo above, each sharing half of the existing Green/Yellow and new Yellow lines. It isn’t quite as complicated as it sounds if you consider the new Silver/Orange line crossing and the new Yellow line to be the same; that is, imagine the new Potomac tunnel as carrying half of the Silver line in the North to become half of the Yellow line in the south as well as half of the Orange line in the north to half of the Green line in the south (they could be mated the other way if you choose). It might seem complicated to represent this with colors, but with letters and/or numbers – I believe that there are only 8 lines in this system (counting the Red and Blue as 1 line each).

        Except for the Blue line, and its lonesome route through Arlington Cemetery, all of the lines would be capable of running to max capacity without interference, despite the branching and reverse branching all over the place.

        • Dave

          It sounds like it would be very difficult to communicate to passengers, e.g. the existing system finds people scratching their heads while looking at a Metro map. It also sounds like it would be replicating the mistake of the Northern Line in London, whereby the suburbs get more frequency on the combined line than the downtown does on the split lines… even though downtown needs the capacity more (there are more people all day long all week long traveling between District stations than between, say, East Falls Church and Ballston). Finally, it would cost a sizable fortune – we can’t even afford a single new line through the District but you’re proposing at least 2 new ones if not a 3rd through northern VA.

          • johndmuller

            I think it’s reasonable to credit the people of Washington with as much intelligence as those of NYC and London. So, under my complicated plan, if one is scratching their head on the platform in Vienna or Tysons Corner, there are probably only two options to think about unless you’re planning to go all the way through the District and out the other side; the same at the common station at East Falls Church, only with more trains. I believe that it is more efficient to have the two options at the outlying stations (and some people waiting for the next train) than to have half the people transferring at the common station, because there would be some non-trivial number of people who could take either train (not that up to half a train transferring at one station wouldn’t be bad enough a thing to avoid). Anyway, people are smart enough to figure it out. After all, only the transit nerds (and we know who we are) need to figure out all possible trips, the regular user only needs to plot a couple of possibilities.

            The matter of there likely being greater traffic on the shared portion of the Orange/Silver lines than on the existing trunk lines in the District is not really a problem with the solutions, but basically just the statement of the underlying problem (i.e., more people want to go through the Orange/Blue tunnel than a single pair of tracks can hold). Seems obvious that there needs to be another crossing, especially as the Orange line could easily be extended further out I-66 and presumably increase its ridership.

            As for paying for this stuff, the original build somehow garnered a far larger federal stipend than most systems could even dream of. Virginia would presumably be on board, as it is largely VA commuters involved in the Orange crush and the District is probably ready to rectify the omission of Georgetown and might go along with a plan that was politically correct enough. If there was such a sweetener, and something could be found to tempt the Maryland side of things (New Carrollton line to Annapolis anyone?) then the old coalition could maybe get some more big bucks out of Congress.

          • Adirondacker12800

            Why would people in Annapolis want to make every stop along the Orange Line when MARC could express them to Union Station and L’Enfant Plaza? And they could change to the Orange Line in New Carrollton if they had the urge to go someplace along the more residential parts of it?

          • johndmuller

            Adirondacker12800 says:
            Why would people in Annapolis want to make every stop along the Orange Line when MARC could express them to Union Station and L’Enfant Plaza?

            Well, one reason is that MARC doesn’t seem to run trains to Anapolis (See MARC map), so it would have to be a bus, which would, of course, be a reason to think about taking MetroRail. If you look at that map (assuming it is approximately to scale), it looks as if Annapolis is about the same distance as is Dulles Airport, slightly beyond which is the planned terminal of the Silver line, so not necessarily out of range for WMATA. One could easily imagine this being a MD/VA political tit for tat; not exactly equivalent situations, but Annapolis is, of course, the state capital, so not entirely without mojo. The name of the game is getting all 3 jurisdictions on board in order to get Uncle Sam to spring for the bucks.

          • Alon Levy

            First, the Dulles extension is a terrible project. The Silver Line should have ended in Tysons.

            Second, Annapolis is a much smaller place than the Reston area.

            And third, is service to Maryland really useful in getting federal money? It’s two extra Senators, but entirely in-state projects have gotten federal money before, as have projects that are not in-state but are only useful for one state (i.e. ARC, which New York gave zero fucks about).

          • Adirondacker12800

            Metro doesn’t have tracks out there either. The people in Maryland aren’t afflicted by the same disease the people in the Bay Area seem to have and haven’t gotten the urge to send the subway deep out into the suburbs. And people in Annapolis are interested in going to Baltimore too. Something they could do with MARC service.

          • Alex B.

            If serving Annapolis is a big goal, extending MARC probably the right choice for a variety of reasons.

            First, Maryland controls MARC. Annapolis is Maryland’s seat of government. Linking to the MARC system can link to both DC and Baltimore. It covers all of the political bases and likely most of the ridership demand.

            Second, the distance from both DC and Baltimore makes regional rail the more appropriate service type.

            The challenge would be cost and constructability. Past rail service (via interurban) to Annapolis ran from Annapolis to the northwest, meeting up with the Penn Line (NEC) and the B&O (CSX) near Odenton and Jessup, respectively. Some of that ROW still exists, a lot of it follows I-97.

            http://en.wikipedia.org/wiki/Washington,_Baltimore_and_Annapolis_Electric_Railway

            If you re-built that rail line (Annapolis to Odenton) and built the appropriate junctions, you’d be able to offer MARC regional rail service to both DC and Baltimore. Build it to a high enough standard and the trains should be able to make up a lot of time relative to cars driving directly to either DC or Baltimore from Annapolis.

          • Adirondacker12800

            Some transit fans think that….. normal people…. want to take 40 mile subway rides. Or that people who live 30 miles away from primarily residential neighborhoods in the inner suburbs want to go to those residential neighborhoods. They don’t because the CVS in their neighborhood is just like the Rite Aid or Walgreens in that neighborhood.

          • threestationsquare

            @Adirondacker12800: I think it’s an artifact of the fact that in North America “commuter rail” means crappy frequency, high fares, and backwards operating practices, so decent service has to be “subway”. Look at how much San Jose is spending (with the support of numerous referenda) to get themselves a 40+ mile “subway” ride to SF because their existing commuter rail is so poor (and MARC is worse). Of course in a sane world MARC would run 2+tph all week and it would be obvious that service to Annapolis should be MARC, but it doesn’t make sense to rebuild the tracks to Annapolis just to give it service like Frederick gets currently.

            Though, given the existence of through-services from Tokyo subway lines to points as far as Narita and Miura (both about 40 miles from Central Tokyo), and the recently-opened Shanghai Line 16 terminating about 40 miles from People’s Square, evidently it’s not just North American transit geeks who think that 40-mile subway rides are a reasonable idea in some situations.

          • Adirondacker12800

            http://fakeisthenewreal.org/subway/

            I don’t want to take a PATH train from Newark to Trenton. Especially since the NJTransit trains can go a lot faster than PATH trains can or ever will. Or an E train to Massapequa if it’s going to make every local stop after Forest Hills.

            It’s an artifact of the farther out you get in North America the less dense it gets. Everyone assumed they would have cheap cars and cheap gas and plopped houses down on two acre lots 40 miles out. Where the metro area doesn’t peter out into farmland 20 miles out. There aren’t enough people out there for a train every 15 minutes.

          • threestationsquare

            @Adirondacker12800: On the page you linked, the map for Tokyo only shows the Tokyo Metro and TOEI-owned sections of lines, and so understates the size of Tokyo’s network by an order of magnitude. For Shanghai it’s just outdated. Here are maps of the subway systems of New York, Shanghai and BART with Warm Springs at the same scale (also I forgot to mention Seoul, where subway Line 1 runs 167km with 78 stops).

            Why shouldn’t some PATH trains run through as locals from Newark to Trenton? It would free up some capacity into Penn Station. Nobody would take them all the way but some people going from WTC to Rahway might appreciate the one-seat ride, and when they get off in Rahway other people will get on who are going to Metuchen and just got off the express from Penn Station, etc. This essentially how through-running from subway to commuter lines works in Tokyo, and I’m pretty sure the Japanese railroads know what they’re doing. Of course in real-world New Jersey the actual answer to “why not?” is “FRA malignance and the fact that the Amtrak dispatchers will usually delay the train enough that it misses its slot at Journal Square causing cascading delays” but neither of those is a law of nature.

            I’m not convinced that it requires all that much density to support a train every 30 minutes. There are lines with that service level in some pretty low-density parts of England and Australia that seem to do fine (or for that matter the Port Washington line). Especially when there’s someplace like Annapolis, Baltimore, Trenton, San Jose or Reading (UK) at the other end, so at least some people from the low-density middle are going in both directions.

          • Adirondacker12800

            http://en.wikipedia.org/wiki/Seoul_Subway_Line_1

            It would make foamers and commuters pine for Shirley Time. PATH trains are slow. PATH tunnels are extraoridinarily tight and the third rail runs out in Newark. The trains going to Trenton go faster than trains using third rail can run under normal circumstances.

            The only way it would free up capacity in Penn Station is if you convinced the people who are packed on the trains now to move to Cheyenne. Nah they couldn’t move to Cheyenne because that would increase the population of the state almost 50 percent.

            in nice round numbers it’s 210 miles from Port Jervis to Montauk. Put a shed over Sunnyside yards and instead of calling the LIRR and Metro North West-of-Hudson services we can call it Line 1.

          • Alon Levy

            Shanghai’s practice of running all-local trains pretty far out could lead to problems later on. It’s not like Seoul and Tokyo, where there are express tracks so that average speeds through city centers are reasonable.

          • threestationsquare

            @Adirondacker12800: Yeah, the loading gauge issue is probably the biggest reason not to do through-running on PATH and other legacy systems, but on future subway systems the tunnels can be built for larger and faster trains (and I think are on newer systems like WMATA and BART) and so this is potentially less of a problem.

            @Alon: Are there express tracks through the city centre on Seoul Line 1? There aren’t on the TOEI Asakusa Line. Express tracks (or alternate routes) through the inner suburbs seem more important.

          • Adirondacker12800

            The people in Trenton who want to go to New York don’t want to stop in Harrison and three times in Jersey City. Or stop every few blocks in and around Sixth Avenue. It takes too long. And those sillly silly people in Newark and Jersey City and the surrounding communities, they want to use PATH.
            In an ideal world the city and the PRR would have come to an agreement to put four tracks of LIRR/PRR tracks under the 8th Ave and 2nd Avenue subways. 100 years ago. 86th Street or so to the Battery. Come together in a bright shiny station somewhere near Wall Street where the trains would head back to New Jersey and Long Island. It’s not an ideal world. Connecting NJTransit to the LIRR via Atlantic Avenue, somewhere near Wall Street and somewhere near Newport is pretty good. It could scare up 20 trains an hour. Which would keep 20 trains an hour out of Midtown. Amtrak says we will need more capacity in 2040 or 2050. I think they are being far too conservative and it will be needed in 2035. Only 20 years from now. They should do the Major Investment Study now. And try to drag in Metro North and the NYCTA in so that the capacity problems in Brooklyn get addressed, Metro North gets direct service to Wall Street and trains to Staten Island get rolled into it.
            Doesn’t matter to me because I don’t have a very good chance to making it to 2050.

        • Alon Levy

          Well, if the new Blue trunk is a weak line, then it shouldn’t be built. Metro can resignal the Blue/Orange/Silver Line shared segment for a higher tph count if all it wants is capacity. Hell, given its recurrent disasters it should be resignaling anyway. My Google Earth-level understanding is that it’s a straight shot from Union Station to Georgetown passing through the north end of Farragut, plus a tail end running on H Street and replacing the newly built streetcar. Could be an interesting line, but if it’s not going to get enough ridership to justify it, it’s not the end of the world if Metro remains a three-trunk operation.

          The half-Blue (or Orange, or Silver), half-Yellow separation avoids reverse branching, and makes sure 14th Street Bridge is on a trunk rather than a branch. The problem, as you note, is that it avoids Union Station. As I said, DC built itself into a corner.

          There’s a good argument that serving Union Station is more important: if the region decides to modernize commuter rail, including electrification and high frequency, it wouldn’t need to boost frequency on the Yellow Line, because it could use the mainline tracks of 14th Street Bridge for extra service.

          • Eric

            I think Metro’s loop plan addresses most of these concerns.
            http://greatergreaterwashington.org/post/21020/metro-maps-out-loop-line-between-dc-and-arlington/

            It serves Union Station, and as pictured, every line is used to its capacity.

            I think I would prefer though if, rather than building an express Silver/Orange line (do they really think they need 4 tracks of capacity?) a new line were built under Columbia Pike, so the Blue/Yellow line could have one end at Huntington/Franconia and the other end at say Bailey’s Crossroads, crossing itself at Pentagon. Then all lines would be segregated from each other, except for Silver/Orange which would share a long central segment.

  10. Adirondacker12800

    It’s just awful the way the LIRR is going to two destinations in Manhattan instead of one. Or the way MetroNorth wants to shift ten trains loads of passengers during peak hours to Penn Station and not send them all to Grand Central. Just awful that some day far far in the future they and NJTransit may go to someplace in the general vicinity of Wall Street and instead of changing trains in Newark or Jamaica people will be changing trains in Valley Stream or Rahway. Just awful.
    Once you have more than three or four lines on your subway system it can make sense to start sending high frequency services one way and the other high frequency services another. Ya live on Queens Blvd and work in the Empire State building you take something other than the E. Work in the World Trade Center the E is wonderful. The F would be really nice but if you live at a local stop something BMTish might be better. Live on the Concourse you have a lot of different ways to get to lots of different places with a one seat ride in many cases or simple cross platform transfer like the people on Queens Blvd have. Having an East SIde line and a West Side line out on the suburban station of the IRT means people get places faster.
    …. some… hipster… who needs to go from DImas Park in Brooklyn to Central Park West was whining about how his trip was awful when the B wasn’t running. On one of these blogs. I stopped looking for alternatives to a one seat ride on the B train when I got up to three and that was without looking at a map. There are those kinds of options when the system has so many lines they can’t use color codes for them unless they want to start doing thing like having the fuschia line. NYC’s is so big that the 26 letters in the Roman alphabet isn’t enough. For clarity I think the IRT diamond services should be using a different number. They’d have to be something like the 17 for Flushing line expresses. Tis’ a pity the IND method of expresses using a single letter and locals using a double letter made touristas heads explode. It made sense to me. And I could easily tell the AA was the local on 8th Ave. And today the map has colors!

    • anonymouse

      Did you even read the post, or did you just skim it for words to anger you before starting in on your rant? The point isn’t that it’s bad to send multiple trains to multiple in-town destinations, it’s that it doesn’t make much sense to have lower frequencies on lines in Manhattan than on lines in Queens, which is exactly the situation you end up with now, due to the way the IND/BMT systems developed historically.

      • Adirondacker12800

        Theres more to life than dumping people from Queens into Manhattan somewhere, anywhere. Those silly silly people having more discrete destinations than “Manhattan” Like getting people from the Upper West Side and the Bronx to those same stations in Manhattan.

        If I’m on platform on 14th Street and I want to get to 42nd Street I don’t give a flying leap where the train is going to turn around. I don’t even care if it’s a local or an express. I get on it and get off at 42nd. If I’m starting out at 201 W 15th and I want to get to 57 W 44th I don’t care that there are trains on the BMT or the IND because I’m going to get on the IRT because that’s the best balance of walking on either end for me. Thinking about in terms of IRT, BMT and IND is very useful. It helps organize the panoply of routes being run.
        It might be different for you start out at 233 W 16th and want to go to 147 W 43rd. If I’m in Forest Hills and want to go to Rockefeller Center I’m going to hope an F come in first. If an E in comes I’ll get on it and hope that we pass an M or an R and I can change to either to get to Rockefeller Center. If I want to go to the World Trade Center or even Penn Station or the PABT I’m going wait for an E. For me waiting for an E makes more sense than taking any train and walking from where it drops me. My “which train to take?” calculus is going to change depending on where I start out, where I want to go and the time of the day. Shit like that happens when the system is so complex it can’t use happy color coding for each of the lines. Or runs out of alphabet.

        • threestationsquare

          Apparently you still haven’t read the post. The issue is not complexity or lack thereof. The issue is that there are tracks that were built in Manhattan at great cost (e.g. the 63rd St tunnel or the Broadway express tracks) that are used at well below their capacity because there’s nowhere outside Manhattan for more trains to go. In New York’s case these things exist for historical reasons and more or less made sense at the time they were built (though we can dream about ways to squeeze more use out of them). Alon’s point is that if you’re building whole new lines like Delhi, Singapore, Washington, or Honolulu, you should try not to spend money on expensive urban-core segments if the intended service pattern will leave most of their capacity going to waste (as Delhi and Singapore recently did and Washington and Honolulu intend).

        • Adirondacker12800

          I read the post. I also understand that utilizing some of the pieces built for a long forgotten plan are going to have some compromises that involve something more complex than getting the maximum number of trains to run over arbitrary tracks.

          • Adirondacker12800

            If you want to get to 65th and Park it matters. It matters if you want to go to Wall Street. It matters if you want to go to Rockefeller Center and not 9th ave and 51st. Or vice versa. Having the E and F skip all those stops in Western Queens means the people in Eastern Queens get a faster ride. And the people in Western Queens can actually get on a train.

    • nei

      I have trouble following your rant, but you’re ignoring some disadvantages. Running the E and F means the frequency for each is halved. While for some destinations as you listed one is more convenient that the other, if you’re going to say near 7th avenue or Washington Square, it doesn’t matter which line. On the return journey, your average wait line is double which is more of an issue off hours. The local R and M are more of a duplicate service. The reverse branching prioritizing one seat rides at the expense of frequency.

      BART has reverse branching with its east bay only line. With timed transfers it doubles frequency from San Francisco to many East Bay stations as the BART tunnel under the bay is at capacity but the East Bay tracks aren’t, so an extra line can run on those.

      As for the B not running, I had a mishap with a bunch of extra transfers by getting off at Herald Square to transfer to a B on Sunday. Oops.

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