Branching and Transfer Breaking

This is the winning option in a poll I conducted among my Patreon backers. Thanks to everyone who participated. Another option, about commuter rail infill stops, came a close second, and I will likely tackle it later this month.

The New York City Subway is unusually branched. I’ve written about the general concept here, and specifically criticized reverse-branching on the subway here. In this post, I want to talk about a more specific feature of complex branching arrangements: they have station locations that make it hard to disentangle the branches without breaking transfers.

 

The left image is a common way junctions are set up. In this image, it’s possible to travel from any leg to any leg; an example of this is BART, with its three-way junction in Oakland between the East Oakland Line carrying trains to Fremont and Pleasanton, the line to the north carrying trains to Berkeley, and the line to the west carrying trains to San Francisco. In many other cases, the branching is simpler, with a clear trunk and two branches, and it’s often not possible for trains to travel between the two branches without backing up; this is like the depicted image with one of the connections missing.

New York has one current example like the left image: the A/C/F/G junction in Downtown Brooklyn has a northern leg (A/C/F), an eastern leg (A/C/G), and a southern leg (F/G). All legs have four tracks and not every track pair connects to every other track pair, but each leg connects to both other legs. It has one former example: the junction between Sixth Avenue Line and 53rd Street Line, with the B/D going south-to-west (then north), the E going east-to-west (then south), and the F going south-to-east. The E/F shared tracks to the east, but neither service shared tracks with the B/D to the south or west.

The problem with this arrangement is that it makes the schedules more fragile. A delay on one branch can cascade. Toronto at one point ran its subway line this, with an eastern and western leg under Bloor Street (continuing to Danforth to the east), and a southern leg under University (looping back north under Yonge); it subsequently ended branching by extending the University leg to the north along the Spadina Expressway right-of-way and operating two independent lines.

The rub is that such an extension usually breaks transfers. Look at the right image: running the lines without branching means no transfers, since there is no station located at the crossing. Toronto dodged this problem because of how the original branching was laid out – in fact, there are two adjacent transfer stations. But usually, it is not hard to convert a branching like the left image into two lines with a simple transfer in the middle.

The 53rd/Sixth situation in New York is a good example of the problem. New York realized it needed more capacity going east, toward Queens, since there were only three track pairs – 53rd Street, plus two more disconnected from the system depicted. For this, it built a tunnel under 63rd Street, and connected it to Sixth Avenue, routing the F through it and creating a new service for Sixth-East 53rd trains, then called the V and now called the M. The junction now looks like an incomplete version of the right image, missing the two upper arcs. The F continues north under Sixth, and only diverts east under 63rd, and has no transfer with the E, which runs east-west under 53rd. The next transfer between the two services to the south is at West 4th Street; the next transfer to the east is at Roosevelt Avenue/74th Street, well into Queens, since the alignment of 63rd Street Tunnel into Queens prevents it from intersecting the E closer in, at Queens Plaza in Long Island City.

The highly-branched nature of the subway in New York makes sure that it is possible to travel between legs even when there’s no transfer, provided one is okay transferring between lines with not-great frequency. The first station south of the junction on Sixth, 47th-50th Streets-Rockefeller Center, lets passengers transfer wrong-way, between southbound and northbound trains. I have used this before to transfer from the B/D to the F on my way between Columbia and Queens, which are not well-connected to each other. Going from east to south is already easy on the M; going from east to north is possible via the M and F, but is unusual, since ultimately both legs lead into the same line in Queens.

However, it is hard to disentangle this to reduce branching. If one believes that reducing branching is useful for reliability and capacity, then one must believe it is necessary for New York to figure out how to split branching in the least painful ways. Partial data from the London Underground is suggestive (see international benchmarking, PDF-p. 15) – the non-branching Victoria and Piccadilly lines are more reliable than the complexly-branching Northern line. Moreover, the intensive service in Moscow, topping at 39 trains per hour without any automation, only works since none of the lines branches. This compels New York and other cities with highly branched systems to disentangle lines.

In the Bay Area, the situation is relatively easy, in the sense of requiring relatively little capital construction. There is no real need for a one-seat ride between East Oakland and Berkeley. The reason there are any trains running on that leg is that Downtown Oakland is on the leg to Berkeley and not on the leg to San Francisco. This was bad planning, and was noted as bad planning even in the 1960s.

What is required is a short bypass tunnel. There are two options. First, a tunnel from the east, replacing the Lake Merritt station with a station a few blocks to the north, effectively moving the junction one station north, so that 12th Street-Oakland City Center can be on the western leg toward San Francisco. Second, a tunnel from the west, between West Oakland and Downtown Oakland. This would not move any station, and put 12th Street on the eastern leg toward East Oakland; Downtown Oakland has a second station, at 19th Street, which would stay on the northern leg, for Berkeley-Downtown Oakland service. Either option would break East Oakland-Berkeley transfers, but make the remaining system more robust.

In New York, disentangling reverse-branches is considerably more difficult. On the numbered lines, it isn’t too difficult to shuffle the 2, 3, 4, and 5 so that the only track sharing is between the 2 and 3, and between the 4 and 5. On the lettered lines, first of all one key connection has to be severed: 11th Street Connection, letting the R go between 60th Street Tunnel toward Manhattan and the Queens Boulevard Line. All trains via 60th Street would go to Astoria; in comments, Alexander Rapp suggests flipping the connection at Queensboro Plaza, letting trains from 60th Street (such as the R) go to Flushing and the 7 go to Astoria, matching the busier line in Queens (Flushing) with the more popular route into Manhattan (60th Street). Queensboro Plaza and Queens Plaza have no transfer, and one would need to be constructed, but even with moving walkways, transferring would involve several minutes of walking between platforms.

Then, the Queens Boulevard Line would be left with local and express services, feeding 53rd and 63rd Street Tunnels. Trains on 63rd have to go to Sixth Avenue. This requires all 53rd Street trains to serve 8th Avenue – the east-west line shown in the images. No more M, just a more frequent E train, with implications for how the A/C run (probably both express between 145th Street and Chambers, where the E terminates). This breaks the transfer, and there is no possible way to create a new one. Transfers between the E and trains on 63rd would only be at Roosevelt and West 4th, and trips from East 53rd to Sixth would require a wrong-way transfer on the western leg using the B/D.

It’s possible to keep the limited reverse-branching and have Queens Boulevard trains of either type, local and express feed either 53rd or 63rd Street Tunnel. Local-local transfers would then be available immediately east of Queens Plaza. The problem is that this still introduces schedule dependence, on what is most likely the most crowded line in the city now that Second Avenue Subway has taken pressure off of 4/5/6 on Lexington. Conversely, without reverse-branching, both choices of how to match lines have drawbacks: sending locals to 63rd and expresses to 53rd means there is no connection between local stops in Queens and Long Island City, whereas doing the opposite makes the connections better but matches the busier Queens trunk (the express tracks) with the less desirable Manhattan connection (63rd).

That said, despite the drawbacks, something like this disentanglement is requires. New York needs more capacity, and shuffling trains like this effectively creates another half a tunnel’s worth of capacity between Queens and Manhattan and allows higher frequency on Second Avenue Subway, useful given the high population density in the part of the Upper East Side that it serves.

For other cities, let this be your lesson: do not build infrastructure that looks like the left image, unless you know how you can convert it to two intersecting lines with a transfer, the way Toronto did. Branching may look like a nifty way to provide one-seat rides between more pairs of origins and destinations, but it will reduce your capacity, and in the distant future force you into difficult choices in which anything you do, including the no action alternative, will screw someone over. What looked like good planning when the IND built subways under Sixth and 53rd in the 1930s turns out to be bad planning today with what we know of how subways operate around the world.

Faster-than-Conventional Rail: Where Could It Work?

Note: this post is secretly about Hyperloop and Elon Musk’s most likely fraudulent claim about the Northeast Corridor. But it’s an interesting discussion more in general. Not all such technology is vaporware the way Musk’s efforts are. See more on The Boring Company’s false claims in a piece I published at Urbanize.LA a few days ago.

The upper limit of conventional high-speed rail seems to be 360 km/h. In Japan, experiments at that speed have succeeded, but there already are problems with noise, stopping distance, and catenary wear, and currently trains top at 320; plans to go at 360 depend on a future Shinkansen extension to Sapporo. In China, the maximum speed is 350, with trains capable of reaching 380 but not doing so in practice. In Continental Europe the maximum speed for new lines is 320-330 km/h, whereas in Britain HS2 is designed for about 350 km/h (220 mph).

Faster technologies exist, in service, today. Shanghai’s Transrapid tops at 431 km/h in service, and JR Central’s under-construction maglev line is targeted at 500 km/h, with tests at 600. Vactrains can go even faster, but are still untested technology (and this includes Hyperloop variants). The question is, where is there room for such technology? So far, Siemens’ attempts to sell Transrapid failed beyond the Shanghai airport connector, an orphan 30 km line going from the airport to the edge of the built-up area of the city. JR Central is building the Chuo Shinkansen maglev between Tokyo and Osaka, but so far there are no plans to extend this technology elsewhere – even within Japan, the state is continuing with building Tokyo-Sapporo as conventional Shinkansen rather than maglev.

The Tokyo-Osaka line is somewhat sui generis. JR Central is currently running about 14 trains per hour at the peak on the Tokaido Shinkansen between Tokyo and Shin-Osaka, each with 1,323 seats, and they’re generally full. It is also old – as the first HSR line in the world, it has a curve radius of 2.5 km (newer lines start at 4 km and go up), and a top speed of 270 km/h. This is exactly the sort of situation that favors new technology. The Tokaido Main Line was a popular intercity line in the late 1950s, but Japan National Railways couldn’t add more express trains without bumping against the capacity limit imposed by slower trains using the line; this tilted it in favor of building the Shinkansen. The Paris-Lyon main line was similarly busy in the 1970s, encouraging the construction of the LGV Sud-Est as a bypass. Nowhere in the world except Tokyo-Osaka is there a full conventional HSR line, except Paris-Lyon – but see later why it is a poor candidate for faster technology.

Track sharing

The main tradeoff with maglev, or even faster technology, is cost. This comes from two places. First, higher top speed requires much more advanced civil engineering, with wider curves, which means more tunnels and viaducts. Conventional HSR can limit costs by climbing steeper grades than legacy trains (the LGV Sud-Est has no tunnels, the legacy Paris-Lyon line does). Maglev can climb even faster grades, but once the speed crosses into the vactrain range, the vertical curve radius required to achieve a steep grade is so wide that it is no longer possible to vertically hug terrain the way European HSR lines do.

The second place is the urban approaches. In theory, this should be a strength of faster-than-conventional rail technology, which has a lower minimum curve radius than HSR at equal speed. But in practice, conventional HSR can leverage existing railroad lines on the urban approaches. At lower speed the stopping distances are shorter, so capacity is higher; the upper limit at speed maybe 12-15 trains per hour, but on a low-speed approach it’s closer to 24-30, so it’s possible to share tracks with legacy commuter and intercity trains.

In Japan, Spain, and Taiwan the HSR track gauge is different from the legacy gauge, so track-sharing is not possible in the major cities, driving up the cost of urban approaches. In smaller cities, Japan and Spain have gauge-change technology, which takes too much time to be of use in capacity-constrained big cities but can allow track sharing on branches. But unconventional technology cannot share tracks anywhere, requiring tunnels on urban approaches. The cost of 20 km of urban tunnel can easily match that of 200 km of at-grade greenfield HSR outside urban areas. The Chuo Shinkansen’s cost, around $200 million per km, comes from the fact that 70-80% of the line is underground, in urban areas and under mountains.

This implies that unconventional technology is most useful when there is limited benefit to be gained from track sharing. This includes the following situations:

  1. The cities served do not have usable legacy rail approaches, or else have a surplus of space within which to build a new approach.
  2. There is no need to branch and use legacy track at lower speed.
  3. There is no preexisting high-quality track that HSR can use, either at high speed outside cities or at medium speed on approaches.

In North America, FRA regulations traditionally led to situation #1. But FRA regulations seem to be changing, which makes track-sharing on approaches more feasible; practically every city has approaches with a surplus of passenger rail capacity (yes, even New York – Amtrak runs 4 trains per hour into Penn Station from the west at the peak, it just uses these slots poorly). In Europe, cities with poor approaches are more likely to be served on a branch, since the rest of the network is so strong. Situation #2 never applies here – branching is always useful, letting the LGV Sud-Est carry not just Paris-Lyon trains but also Paris-Marseille, Lille-Lyon, London-Lyon, Paris-Geneva, etc.

Some of the stronger intercity travel markets are in situation #3, but most aren’t. In North America, the Northeast Corridor has long stretches of high-quality track, either already capable of high speed or capable with a small number of curve modifications. That characteristic alone makes it exceptionally bad for unconventional rail technology: such technology would need a new alignment through hundreds of kilometers of suburbia in Massachusetts, Rhode Island, New Jersey, Pennsylvania, and Maryland. Toronto is also a poor candidate for unconventional technology, since it has a long stretch of suburbia in both directions with high-quality four-track commuter rail, straight enough for 200 km/h or even more. Significant suburban tracks are also useful in California (Caltrain, parts of Metrolink) and Chicago. Only the Pacific Northwest, Portland-Seattle-Vancouver, has a real shortage of usable legacy track even on the approaches. So is it a good candidate for unconventional technology? No, for reasons of distance.

The optimal distance

Faster-than-conventional rail is silly at short distance. The difference in travel time is smaller and does not justify the expense. Access and egress times are fixed, and may even go up if the station locations are less central (the Chuo Shinkansen won’t serve Tokyo Station but rather Shinagawa, a few km south of the CBD). So focusing on in-vehicle time is less useful. The Chuo Shinkansen is really at the lowest end of what is acceptable. It works because, again, the Tokaido Shinkansen is at capacity. Tokaido is also relatively circuitous in order to avoid mountains – the distance from Tokyo to Shin-Osaka is 515 km on the Tokaido Shinkansen, 438 on the Chuo Shinkansen, and 405 on a straight line. On the Northeast Corridor, the New York-Washington distance is 362 km on the railroad and 330 on a straight line, a much smaller difference.

Conversely, faster-than-conventional rail is questionable at very long distance. At maglev speed, a New York-Los Angeles train would take perhaps 12 hours, not really competitive with planes for people who don’t mind flying. At vactrain speed, the train would be competitive. However, in either case, trains require linear infrastructure, and repackaging them as a new Hyperloop doesn’t change this basic fact. Ignoring the effects of terrain, a 4,000 km vactrain or maglev line costs ten times as much as a 400 km line. This is not the case for air travel, which requires no fixed infrastructure between the airports.

There should be a good zone in the middle, say the 1,000-1,500 km range. This includes city pairs like Beijing-Shanghai, New York-Chicago, Tokyo-Sapporo, Tokyo-Fukuoka, Delhi-Mumbai, Delhi-Kolkata, and some international European pairs like Paris-Madrid. Going up to 2,000 there are also New York-Miami, Chicago-Dallas-Houston, Beijing-Guangzhou, and Los Angeles-San Francisco-Seattle; in China, where conventional HSR is faster, even 1,000-1,300 km is well within conventional HSR capabilities (Beijing-Shanghai is 1,300).

However, the fact that there is this sweet spot for unconventional rail does not mean that the construction costs are affordable. This remains a question mark. Maglev costs are either in line with HSR costs at equal tunnel proportion, or somewhat higher. The Shanghai maglev cost 10 billion RMB in 2003, which in PPP terms is maybe $100 million per km for an elevated suburban/exurban line (bad, but not terrible), and in exchange rate terms (imported technology) is somewhat more than half that. The Chuo Shinkansen seems to be $200 million per km, 70-80% underground, which is in line with urban tunneling costs in Japan but high by the standards of exurban tunneling (the 60% tunneled extension of the Tohoku Shinkansen to Shin-Aomori was $55 million per km).

The upshot is that a New York-Chicago maglev is likely to cost like 1,200 km of HSR. The western half of this line is easy – maybe a short tunnel in suburban Chicago is required, but there’s so much right-of-way space that an above-ground urban approach should be fine. The eastern half of this line consists of 600 km of pain in the Appalachians, suburban New Jersey, and a new tunnel under the Hudson. Costs approaching $100 billion are likely, and I don’t know that the benefits are commensurate.

Can you start big?

A short maglev or vactrain is of little use. Given the expense of approaches, the best use of expensive infrastructure may well be to build multiple lines using the same approach. For example, not just New York-Chicago or New York-Atlanta-Miami, but both at once, to take advantage of the same maglev tunnel under the Hudson. By itself New York-Chicago might be good enough, but it’s unclear – it’s nowhere the huge benefit/cost ratio coming from a program for conventional HSR on the Northeast Corridor at normal first-world rates.

I think this is the biggest risk with unconventional rail technology. Its basic characteristics suggest that there should be a distance range at which it works well – not too short so as to offer too little benefit versus conventional HSR, not too long so as for construction costs to grind it down. But it’s equally possible that the two bad zones, too short and too long, really overlap, so that 1,200-km lines are still too expensive to compete with planes while not offering enough speed benefit over conventional HSR to justify all this new construction.

The problem, then, is that it’s difficult to start big with a risky technology. The shortest useful maglev segment, Tokyo-Nagoya, is still well over $50 billion, and Tokyo-Osaka approaches $100 billion. This is on a route with proven demand; what about routes that don’t parallel overcrowded conventional HSR? Some government will need to take a $100 billion gamble on a long route hoping that the 1,200-km niche really exists.

The Lagos Metro

Lagos is the second-largest city in the world without rail rapid transit (the largest is Karachi). Sources disagree on its population, but it looks like 21 million in the built-up area, consisting of most of Lagos State plus a few suburbs just outside it, such as Ota and Ijoko – in total, 1,000 km^2, someone more including the suburbs. All of the problems that rapid transit intends to fix – traffic jams, pollution, long commutes, overcrowding, unpopular jitneys – are present. I don’t want to repeat the case I made in this post in favor of aggressive investment in subway systems in Lagos and other big third-world cities. Instead, I want to talk about concrete features.

Here is the map – it’s slightly different from the version I circulated in previous posts. Note the following features:

1. Four of the lines – East-West (blue), Main Line (red), Ikorodu (brown), North-South (purple) – are four-track. This is because Lagos is so big that its outer margins require very wide stop spacing, which requires four tracks. The first three also run in wide enough rights-of-way for significant stretches, making four-track elevated structures easier to construct. Express stops are denoted with squares, local ones with circles. If two four-track lines intersect, the stop is denoted with a square, and is express for both lines. All four-track lines have two-track tails – the farthest-out square is the last station with four tracks, where locals turn, while expresses keep going to the end. Only one four-track line has an end without a tail: the Main Line terminates all trains at Leventis.

2. On the four-track stretches, the average interstation is a little less than 4 km. Average speed can approach 60 km/h, given that the rights-of-way are often quite straight. On the local tails of these lines the average looks like 2 km, or around 50 km/h. On the two-track radial lines, the average interstation is a little less than 1.5 km, or around 40 km/h; the difference with the local tails of the four-track lines is that the local tails are in suburban areas.

3. Every pair of radials intersects, usually in Lagos Island but sometimes elsewhere. Four circumferentials – Apapa (dark red), University (ochre), Ishaga (dark green), Idimu (magenta) – intersect all the radials. Whenever two lines intersect, there’s a station. Doing this requires a lot of lines to run in the same alignment in the center. This is not track sharing, but multi-track tunnels. The only eight-track tunnel, where the Main and Ikorodu Lines run together between Eko Bridge and Leventis, has a wide road to go under; the only ten-track el, where the East-West, Ota, and Ikorodu Lines parallel around the National Theatre, has an entire expressway to go over.

4. The southern ends of the Ota (yellow) and Ikeja (silver) Lines are in open water today. This is because the area is slated for land reclamation and intense development, called Eko Atlantic. The western margin of that area, around the station I call Eko Atlantic, is already reclaimed, but still undeveloped. That entire area (Victoria Island) is the favored quarter of Lagos, and is commercializing; farther east, in Lekki, there are grand plans for suburban redevelopment, and an immense amount of casual marketing in the media (“buy now and the land will triple its price in five years”).

The system I’m proposing differs from the current proposal. The current proposal only has five radials (with apparently just one crossing from the Mainland to Lagos Island), corresponding to my East-West Line, Main Line, Ota Line, and a hybrid of the Ikorodu Line and the two branches of the North-South Line; there is one circumferential, vaguely corresponding to my Idimu Line.

Some of the features of the current proposal are a good start. It’s not possible to build eighteen lines at once, and some prioritization is required. It’s even fine to start with shared tracks into Lagos Island and subsequently give lines their own way into Lagos Island. (On my map, everything paralleling the three existing road bridges is a bridge, the rest are tunnels).

However, the existing proposal suffers from several shortcomings, which will need to be fixed later:

  • The stop spacing is too wide even in the center, intermediate between my local and express tracks.
  • There is far too much branching. In any reasonable sequencing of the lines, the East-West Line will fill before the later ones (i.e. the ones going north-northeast) open, requiring new routes into Lagos Island.
  • There isn’t enough service in Victoria Island, which is developing as a CBD, as is common for rich neighborhoods.

But the worst problem is that the under-construction route goes elevated along the Ring Road, skirting Lagos Island, with just two stops, Ebute Ero and Marina. This segment has little value and should be demolished once direct underground routes with more stops open. According to a paper that’s no longer online, one of the reasons third-world subway lines tend to underperform ridership expectations is that many of them use available rights-of-way and skirt the CBD, instead of building short tunnels to get to the center. This paper in turns is one of the references used by Bent Flyvbjerg in his paper arguing that in general urban rail has cost overruns and ridership shortfalls.

The big obstacle for constructing any subway system is cost. This is especially true in Lagos, where the construction cost of the current project (the Blue Line, corresponding to the inner part of the western half of my East-West Line) looks like $180 million per km, entirely elevated. I say “looks like” because while the cost is consistently $2-2.4 billion in exchange rate terms (around $5 billion in PPP terms), it’s not completely clear whether this is the Blue Line or also the Red Line.

My proposal is largely elevated, but the Lagos Island segments have to be tunneled. So do some other segments, for examples the inner parts of the North-South and Ikeja Lines, and most circumferentials. The system, totaling about 900 km, of which 200 is four-tracked, looks like it could be built only about one-quarter underground, or slightly more. Moreover, much of the underground construction could be cut-and-cover, including several segments in Lagos Island, and most of the circumferentials; only the underwater crossings and a few off-grid Lagos Island connections have to be bored.

The main analytic point here, carrying over to other cities, is the importance of prior planning. My map has 18 lines. This is useful because figuring out where stations should go, which stations on four-track lines get to be express stops, and how to sequence the lines should be based on long-term considerations. As I hinted in a post written right after I finished the first version of this map, about subway lines that intersect without a transfer, building the best lines 1-3 requires having a good idea where lines 4-12 will go. So even if Nigeria runs out of money after the first two lines are built, figuring out the built-out network is not useless – it informs the current network, and makes adding future lines less painful.

This is true for reducing construction costs, and not just for a good network. One of the positive features of the Paris Metro is that nearly all of it was planned as a whole, and as a result, difficult stations like Chatelet, Etoile, and Nation were built with the intention to have multiple Metro lines serve them. This meant that the stations could be built once, rather than multiple times, once for each line. Two lines, Metro 8 and 9, even run alongside each other for 1.7 km under the Grands Boulevards, which are wide enough for a four-track subway.

The planners of every system, regardless of whether it’s a metro for a city that doesn’t have any urban rail or an extension in a city with fifteen lines, should always think ahead. What are the future plans? What are the future needs? What is the expected future growth? In Lagos, the answer to the last question is “fast demographic and economic growth,” and this means the city should plan on a large system – hence my almost gridlike system of radials going north and northwest and circumferentials crossing the Mainland going southwest to northeast. But really, every city needs to ask itself how it wants its rail network to look, and plan the highest-priority segments accordingly.

A Marshall Plan for Third-World Infrastructure?

At the G-20 meeting, an Ivorian journalist asked President Macron about the Marshall Plan and if Europe would do the same for Africa. Macron gave a long-winded response, including some deservedly-mocked zingers about Africa’s “civilizational” problems and how women have 7-8 children (see my own response here). But buried in that there was an interesting point I’d like to expound on, about the difference between the Marshall Plan and current aid:

I don’t believe in this reasoning, forgive me for my directness. We among the West have been discussing such Marshall plans for Africa for many years and have in fact given many such plans already. So if it was so simple it would be fixed already. The Marshall plan was a reconstruction plan, a material plan in a region that already had its equilibriums, its borders and its stability.

Jane Jacobs said something similar, in either The Economy of Cities or Cities and the Wealth of Nations, I forget which. Her argument was as follows: postwar Europe lay in ruin, but the business culture, social networks, and so on were still there, so rebuilding infrastructure could restore prewar prosperity and seed future growth. Even with the disruption caused by the mass carnage, there were enough skilled workers who knew the local business culture for the economy to recover. Thus, per Jacobs, and per Macron, Marshall Plan-type programs for developing countries, which are poor rather than in ruins, have no chance of succeeding.

And yet. There are some complexities in the above description. The first is that postwar reconstruction in South Korea, which had never been a developed or even middle-income country at that point, was useful. Literacy rates rose rapidly, after WW2 and again after the Korean War, going from 22% in 1945 to about 71% in 1960. The schools were often built not by the Korean government but by the US or by Christian missionaries (Korea was the cause celebre at the time, and the origin of the trend of Americans adopting children from poor countries).

The second complication is that in post-conflict situations, there is a role for reconstruction aid. Libya was never a developed country, but it was richer before the civil war than it is today, and could have used reconstruction before the war resumed in 2014. Niger and Mali (two of the few countries that are so poor Macron’s epithet about 7-8 children per woman might apply) in particular have had recent conflicts, dragging down growth, especially in Niger.

The third is the subject of this post: infrastructure. In theory, this is a one-time investment, which can be done with an outside infusion of cash plus some tech transfer. This means, first-world consultants helping design rail networks, water infrastructure, roads, subways, and power plants, and on the way training local workers in how to do maintenance and how to design and engineer future expansion. Europe and the US practically never do that anymore, but Japan still does and China has started doing so as well; Kenya is building intercity rail with Chinese money, buying Chinese equipment. In theory, this is worthwhile investment, since the recipient countries have very weak currencies and high expected growth rates, which depresses current-dollar construction costs while maintaining decent future current-dollar profits.

And yet. There’s a number of subway projects in developing countries built with foreign financing and technical expertise, chiefly Japanese. I singled out two for their high construction costs, in Dhaka and to a lesser extent Jakarta. Dhaka is setting world records for elevated construction costs – higher in absolute terms than in the US, and unimaginably higher relative to local incomes. Jakarta’s costs have risen further since I last wrote the post, and currently stand at $1.7 billion, or $5.4 billion after PPP adjustment, a total of $350 million per km for a line that’s only 60% underground.

There is a dearth of indigenous expertise in how to build rail infrastructure in developing countries. Unfortunately, the first world cannot supply this expertise, because the first world’s expertise is in how to build rail infrastructure in rich countries. As I noted a month ago, rapid transit construction in the third world needs to take into account the difference in relative costs of labor and capital between rich and poor countries; in comments, Ian Mitchell suggested resuscitating the methods of the 1910s, when American incomes were about the same as in the more functional third-world countries today, like India and Nigeria. There is no real expertise in how to do that, and it is unlikely that international consultants, who expect to do most of their work in rich countries, will bother to learn.

After the initial construction phase of the Delhi Metro, the system worked on indigenizing itself – that is, on using more local capital rather than relying on foreign consultants. The cost reduction, as far as I can tell from links that are now dead, was 15% – substantial, but not a game changer. India remains one of the highest-cost countries in the world. It’s possible that it learned all the wrong lessons – as it developed local expertise, it figured out how to build rapid transit using the construction methods of the first world.

This is unlikely to have been an accident. Poor countries, and even middle-income ones, are full of cultural cringe, in which acting like the rich world is a positive status marker; ex-colonies frequently act this way toward their former colonizers. The political system within the countries in question encourages elites to show that they can be just like the Europeans or Americans or high-income Asians. Those elites are fervently nationalistic, but this often means showing the world that India can have what Britain and the US have. Thus there is an internal political bias toward solutions that do not work. Ironically, first-world consultants are the best-placed people to recommend using different construction techniques, suitable for low labor costs, but they are unlikely to suggest them, again since their expertise is in high-labor cost environments.

So having a Marshall Plan-style program in which rich countries build infrastructure in poor countries is a recipe for high construction costs. Can it at least result in good projects? The answer is, again, mixed, for two reasons.

The first reason is that it isn’t easy to realize profits from infrastructure investment in foreign countries. The poorest ones have a high risk of relapse into civil war. The next tier of countries – the Kenyas, the Bangladeshes, the Vietnams – are more stable, and in theory offer a good investment, with reduced risk of economic collapse. The problem is that as they get richer, they will necessarily be more nationalistic and more capable of asserting themselves. The same xenophobia that leads people in expensive British, American, and Canadian cities to scapegoat foreign investors, often Chinese, for high housing costs, applies just as well to poor countries. A richer Kenya is a Kenya that is more likely to find it offensive that it depends on China for its railroad network. If there is significant profit extraction from Kenya to China, then it’s because Kenya’s economy has grown, allowing it to threaten to impose capital controls or nationalize the railroad. This means that a strategy of spending money in a poor country now to make profits later as it gets richer has too much political risk, regardless of how much the country signals commitment to letting foreigners make a profit in it today.

The second reason is that the projects themselves may not be optimal. This is the same problem as the construction cost problem. International consultants are used to principles that are true in the cases they have the most experience in, which are usually in rich countries and occasionally in middle-income ones. I’ve had trouble drawing good fantasy maps in Israel, a borderline rich country, purely because its ethnic divisions are so different from those of any other rich country: in comments here and at Sandy Johnston’s place, Shlomo reminds us that the ultra-Orthodox use transit profoundly differently from everyone else. With my knowledge of European mores, I can confidently say that even in European countries I don’t know well, like Spain, this is at most an edge case. Can I say this of Nigeria? Maybe not. Can I say this of Niger? Lol.

This lack of local knowledge is compounded by the fact that, as with the construction cost problem, local elites want the appearance of a Western- or high-income-Asian-looking system. This does not mean they want to build subways, rail networks, modern sewage systems, household electrification, etc. just for show. On the contrary, in the better-functioning third-world countries even very corrupt leaders genuinely want their respective countries to be more successful. The problem is that they are unlikely to be experts on what a good subway, sewage, etc. system should look like, and base their ideas of what works on what they have seen work in the first world. Third-world adaptations are often creatively different, for example an NGO is installing elevated water pipes in Kibera, to avoid expensive underground engineering required to eliminate seepage, and to deter metal and water theft (Kibera is notorious for both).

There is no way around painstakingly developing local expertise in infrastructure construction and operations. It’s something that engineers in poor countries can learn from rich countries, but they would need a good understanding of first principles in order to adapt to local situations. It’s not something that a consultancy could trivially do.

So, is there room for a Marshall Plan? The poor countries in question could certainly use the money. The problem is that the sum total of what they need to invest in – physical infrastructure, schools, public health, legal institutions – stretches not just their tax capacity but also the generosity (some would say guilt) of any first-world country. What I think Lagos needs to spend on building a metro system is on the order of $200 billion in PPP terms; in exchange rate terms that’s $60 billion, compared with $90 billion in annual aid given by EU members, in total. Lagos needs more investment than just the subway, Nigeria is more than just Lagos, and the total population of countries poorer than Nigeria is more than a billion. Even counting foreign investments that the donor country intends to recoup but probably will not, this is not nearly enough. So what we’re discussing is not really a Marshall Plan equivalent in which the donors help rebuild infrastructure in the recipient countries, but usual foreign aid politics, in which (from the perspective of the recipients) foreign aid is one additional revenue stream with its own strings attached.

Line Spacing, and Intersections Without Transfers (Hoisted from Comments)

This post is inspired by two separate things. The first is my work on a fantasy subway map for Lagos; here is the current live version. There are twelve radial lines, all serving the western half of Lagos Island, converging on nine transfer stations. Under the principle that whenever two lines intersect there should be a transfer station, this greatly constrains the paths the lines can take. Result: the path between two CBD stations, Eko Bridge and Leventis, carries ten tracks underneath it. This is under a wide street, and it might be possible with a double-deck four-track-wide tunnel and two more tracks deep-boring around it, but it’s not easy to construct.

The second inspiration is a post by Brian Stokle about subway line spacing. Brian looks not at spacing between successive stops on one line, but at spacing between parallel lines, averaging a few North American examples. The average is a little higher than half a kilometer, narrower than the typical stop spacing. On Twitter, Joshua Mello notes Boston’s spacing was narrower; in comments, I add examples from New York and Paris, which are a bit narrower than Brian’s examples but wider than Boston (New York is one block in Midtown, so 280 meters, and Paris is 300 between Metro 3 and Metro 8 and 9).

These two examples together illustrate the tradeoff in subway construction. Most subways have a stop every 1-1.5 km; newer systems are at the high end of this range, mostly because of the demographic weight of China. It’s normal for stop spacing to tighten in the core, but not to a large extent. In Tokyo, the average stop spacing is 1.2 km, and in Central Tokyo it’s perhaps 800 meters. In London, the Tube lines seem to tighten from an average of 1.2-1.5 km to 600-800 meters in Central London.

At the same time, subway line spacing is necessarily short. The reason is that modern CBDs are geographically small. Midtown is maybe 4 km^2, from 30th to 60th Streets and from between 2nd and 3rd Avenues to between 8th and 9th. The Paris CBD, from just west of Les Halles to just east of Etoile, is also about 4 km^2 (see job density on PDF-p. 6 here). The Tokyo CBD, defined around Otemachi, Nihonbashi, Hibiya, Shimbashi, and increasingly Roppongi, is maybe 5-6 km^2, in a metro area of 38 million people.

Subway networks in such CBDs are necessarily crowded. The CBD is where people want to go. A subway line can get away with skirting it – Paris M4 does, and is in a near-tie with M1 for highest ridership per km. But avoiding it entirely is a ridership killer, except specifically for circumferential lines concentrating off-CBD travel: in Paris this suppresses M10 ridership, and in New York, it suppresses ridership on the J/Z (even though they serve Lower Manhattan) and the L (even though it serves Union Square). This means that the CBD of a large city will have many subway lines converging on a relatively small area. New York has its five north-south lines through Midtown.

Ensuring that every pair of intersecting subway lines has a transfer in this environment is difficult. Line spacing is usually narrower than station spacing, requiring kludges like the block-long walkways in New York, such as between Times Square at 42nd/7th and Port Authority at 42nd/8th. Paris managed to have an almost perfect network – before M14 was built, it only had one missed connection, between M9 and M12 (built by a competing private company) – but only by having very short station spacing, unusual even by the standards of the early 1900s, ruling out significant suburban extensions of the kind that are routine in London and Tokyo.

The situation in smaller cities is actually easier. The CBD is very small, often smaller than a square kilometer, but there are fewer lines, so it’s easier to make sure lines intersect properly. It’s also much easier to get line spacing right outside the CBD, where there’s less intense demand, allowing line spacing compatible with stop spacing on any intersecting or circumferential line.

The fundamental issue here is really about planning for the future. It’s not hard to gets lines 1, 2, and 3 to intersect nicely, or even lines 1-6. But beyond that, a city will often find itself in a situation where the best street alignment for line 7 happens to be right between two stations on line 1, spaced too far apart for a transfer. This is what happened to Tokyo. In New York, the three constituent systems (IRT, BMT, and IND) were each internally planned cohesively, so when two lines within the same system intersect, there’s a transfer, and, with difficulty, the IRT/BMT intersections have transfers as well. But the IND connects poorly to the other two systems, sometimes deliberately, and the IND’s layout made future extensions and service changes break transfers. My proposal to reduce reverse-branching in New York runs into the problem of breaking the transfers designed by the IND around a specific service plan.

When lines are designed together, it’s easier to avoid this problem. Paris M8 and M9 share a route through the center, as they were built simultaneously as the street is wide enough for four tracks. In contrast, building a line under or next to an existing line is much more difficult; New York did it anyway, under Sixth Avenue, but this led to cost overruns that doomed the IND’s early plans for further expansion. It is also difficult to build a new station under an existing transfer station, as it usually requires underpinning; in Paris, this problem means that transfer stations tend not to have closely-aligned platforms, requiring long walks between lines. When I’m proposing running multiple lines in the same tunnel in Lagos, this is from the point of view of assuming coordinated planning, with sequencing that allows entire streets to be dug up at once.

However, in reality, even coordinated design has its limitations. Subway networks take multiple decades to build, and in the interim, the city changes. Planners can attempt to use zoning to shape city development in a way that facilitates further expansion, but some tendencies are too uncontrollable. For instance, high-income neighborhoods tend to commercialize; I mentioned Roppongi as a growing part of the Tokyo CBD earlier, which is an example of this trend. The hottest new part of New York commercial development, the Meatpacking District, is really not a subway hub. This means that even if a city plans out lines 1-12 to share tunnels appropriately, it may not be able to control where there will arise the most demand for line 13. Coordinated long-term planning makes things easier, but it will not solve the basic problem of optimal subway spacing and CBD size.

My Patreon is Live

Here is my Patreon page. Donations get processed on the 1st of every month; if you contribute today, my understanding is that it will still only get processed in August. I’m still working on the Lagos post solicited via Twitter, but should be done in a week, depending on how much time I have. (The subway meltdown in New York and Cuomo’s laconic response thereto mean that I’m on deadlines at a bunch of outlets that want my opinions.) When I’m done I’ll start doing internal Patreon polls about the next post’s topic.

My posts are going to remain public. Instead, the rewards are as follows:

$2/month (“diesel bus”): you get to vote in the polls about my topics. Not all posts will be polled, but at least one per month, ideally 2-3, will be.

$5/month (“trolleybus”): you get dedicated content, in the form of various examples or caveats that are cut from my published pieces due to length. Things that I cut because I couldn’t find good enough evidence for them don’t count; only things that I’d be comfortable saying in public, but didn’t because of length or flow, do.

$10/month (“tramway”): you get listed as a supporter on a sidebar of this blog.

$25/month (“rapid transit”): you get to tell me what to write about, bypassing the polls, a couple times a year – at least twice, possibly more depending on schedule and on how many people ask for the same thing. (If two people keep asking for the same thing, they really get a minimum of two posts each, so four total.)

My current target is a total of $200/month, based on what people said on Twitter. If I get a lot more than that, I can start committing to more than one post a week.

Modeling Jitney-Bus Competition

I just published a piece at the Bay City Beacon about Lyft Shuttle, the company’s foray into fixed-route buses. In the piece, I mentioned briefly that adding a competing operator can reduce the average quality of service. The piece, nominally 500 words, really 700, was far too short for me to expound on the model, even though people on social media had asked me about it before. So here it is.

The first assumption is that the routes are identical. This is largely true for some of the more northern Lyft Shuttle routes, duplicating Muni’s 2 and 41 buses (the 41 duplicator skips some inner stops, though).

The second assumption is that the bus has a fixed schedule, but the jitney can schedule itself in response to the bus. This is true of the case studies I know of (and, to make it very clear, “case study” means “I’ve read an article” or “I’ve heard it discussed on social media”): Israel’s Sherut vans, and Hudson County’s private jitneys. Both use dynamic schedules, which in plain English means drivers radioing each other (in Israel) or employing lookouts (in New Jersey); the bus companies have fixed schedules that are slower to change.

The third assumption is that marginal riders take whichever route they see first. This is the case with regular jitneys. Not all riders are marginal: there might be an explicit ethnic dimension, e.g. dollar vans in New York are more popular with unassimilated immigrants, because they provide amenities like use of their own language rather than English. Lyft Shuttle is booked via app, so the situation there is murkier; however, most likely the use case will involve passengers buying a ticket a few minutes in advance, possibly checking against a bus app to see which will come first. Some people will stick with one system over the other (tech boosters seem to hate public services, people without other reasons to download the Lyft app will probably stick to the bus), but some will be flexible.

Let us work this out first assuming perfect scheduling and then introducing schedule irregularities due to bunching.

Now, let’s assume the public bus arrives every 6 minutes. If the transit agency wishes to double service, it will schedule additional service at the midpoint between each pair of successive trips, providing 3-minute frequency. But if additional service comes from a private operator, the incentive is to schedule to compete and not to cooperate. Say the public bus arrives at my station at :00 on a 6-minute takt. The private operator can schedule itself to arrive at :03 on a 6-minute takt and get half of my station’s traffic, or it can schedule itself at :05 and get 5/6 of its traffic. Let’s set the fudge factor at 1 minute for now: if the separation is smaller, for example if the jitney comes at :05:30 and the public bus at :06, then I see both at the same time and am indifferent as to which to ride.

By itself, this still means adding service. However, it’s likely that there is going to be some service diversion – that some public bus riders will switch to the private service (e.g. because it usually comes first). If one quarter of the bus riders switch, then the schedule is cut to a bus every 8 minutes. The jitney still aims to arrive 1 minute before the bus for maximum revenue, perhaps getting bigger vehicles if it needs the capacity, as the New Jersey jitneys did. So now my bus comes at :00, :08, etc., and the jitney comes at :07, :15, etc. Average wait time is 3.125 minutes, whereas before it was 3 minutes.

The formula in general if both vehicles come every x minutes and are separated by 1 minute is \frac{(x-1)^2 + 1}{2x} and this equals 3 at x = 4 \pm \sqrt{14} \approx 7.74, corresponding to about 23.5% reduction in transit use; any higher reduction makes average wait times worse. If the original headway was y, then we have x = 1 + y/2 \pm \sqrt{(1 + y/2)^2 - 2}, or just under 2 extra minutes; the fixed separation, 1 minute, means this calculation is not scale-invariant.

Now, let’s introduce schedule irregularity into this system. As a toy model, let’s look at what happens if the bus can be up to 1 minute behind or ahead. If the route only has public buses, and one bus is off by 1 minute, then instead of two 6-minute gaps there’s a 5-minute gap and a 7-minute gap, for an average wait of 3:05. If the route has public buses and jitneys, scheduled 1 minute apart as above, then a 1-minute error is good for passengers if it evens out the schedules (it converts a 3.125-minute wait to a 2.5-minute wait), but bad for passengers if it makes the bus and the jitney arrive at exactly the same time (the wait rises to 4 minutes).

But really, bus schedules are an unstable equilibrium. (So are train schedules, but the instability is too slow to cause bunching). If a bus is a minute behind, then at the next bus stop it will have an above-average crowd size, since people had more time to show up and wait. Boarding time is a significant fraction of bus travel time, so the bus will go behind even further, until the bus behind it will catch up, at which point the two buses will leapfrog each other. It’s possible to reduce this effect by cutting boarding time, via low-floor buses and off-board fare collection with all-door boarding; Muni has implemented both, but this is still not enough to remove the instability. In practice, this imposes a minimum headway of about 3 minutes – below it, buses bunch so much that adding service doesn’t add any capacity. In theory it’s possible to go lower, but when ridership is high enough to justify 3-minute headways, it’s high enough for dwell times to make lower headways infeasible.

Jitneys do not have a 3-minute minimum headway; they’re more flexible about running express if they’re already full. This, in turn, means that schedules on jitney routes are more irregular than on buses, making wait times less predictable, and ultimately longer (since, at equal service, less even intervals translate to longer average waits). But more to the point, jitneys still aim to schedule themselves to come just before the bus does. This means that jitney arrival irregularity largely tracks bus arrival irregularity. So with this in mind, if the city bus gets delayed by a minute again, and the jitney adjusts, then we have the following service gaps, in minutes: 8, 1, 6, 1. Average wait time is now 3.1875 minutes.

So the question is, what effect does demand diversion from buses to jitneys have on bus irregularity? The answer is, not much. This depends on additional assumptions on dwell times and the initial delay. Delays compound exponentially, but the exponent (“Lyapunov exponent” in dynamics) is low; on a 6-minute bus route, a 1-minute delay means that future dwell times go up by 1/6, and at 2.5 seconds of variable dwell time per boarding or alighting (Muni average with all-door boarding, see PDF-p. 16 here) it takes 60*6/2.5 = 144 boardings and alightings to delay the schedule by another minute. Muni averages 127 boardings and alightings per hour, so it takes more than an hour for the 1 minute of delay to compound by another minute (strictly speaking, by \sqrt[6]{e} \approx 1.18 minutes). The busiest bus in North America, Vancouver’s 99, averages 320, so the compounding takes just 27 minutes (almost a full one-way trip); Vancouver buses with comparable ridership to the routes Lyft is duplicating average maybe half that.

The point of this exercise is that on the timescales relevant to a bus route, schedule irregularity is approximately linear. So demand diversion from buses to jitneys has a linear effect on schedule irregularity: 25% diversion means that instead of a 1-minute delay there’s only a 45-second delay. A 1-minute delay with 6-minute buses is still better than no delay with 8-minute buses an jitney spaced a minute apart, so the jitneys still remove value. At higher delays, this is no longer true (average wait time is quadratic in the delay); the point of equality is about 1.61 minutes of bus delay due to schedule instability (other delays, like traffic, affect all routes equally regardless of frequency). So jitneys can add value on long, busy routes (don’t forget – the lower the headway, the more significant the assumed 1-minute separation is). But the routes the Lyft Shuttle jitney runs are less busy, and more importantly are short, with less opportunity for delay compounding; delays do not compound past the terminus with decent dispatching.

The upshot is that jitneys do not universally remove value from transportation networks. But on short 6-minute routes, they do even under mild assumptions on ridership diversion. There’s more service in operation, but from the riders’ perspective, wait times have increased and regularity has degraded. The logic of competing private companies is not always the logic of better service for passengers. Sometimes, having a government monopoly inherently improves efficiency.

Quick Note: What a Few Pictures Tell Us About BRT

The Boston BRT initiative is pushing hard for what it calls gold standard BRT in Boston, with the support of ITDP. Backed by a Barr Foundation grant, it launched a competition for pilot routes. Two years ago to the day, Ari Ofsevit already wrote a takedown of the idea of gold standard BRT in Boston, comparing the street width in Boston to the street widths in Bogota and Mexico City. In brief, most of Bogota’s BRT network runs on streets wider than 40 meters, and the rest is still 30-something; in Boston nothing is that wide except streets that have light rail in their medians like Commonwealth Avenue and Beacon Street, and the key corridors have segments going below 20.

In response to this problem, here is the photo Boston BRT is using to illustrate the technology:

BRT in not-Boston

I am not sure where this photo was taken. Judging by the 60 speed limit sign, it can’t be in the US. What we see in the photo is 4 travel lanes in each direction (2 car, 2 bus), a generous median for the station, generous medians on both sides of the main road, and service lanes. Paris’s 80-meter-wide Cours de Vincennes has in each direction a service lane, two parking lanes, one bus lane, and three car lanes, but no median between the two main carriageways. The depicted street has to be wider, which means it’s wider in meters than most Boston arterials are in feet. It’s very wide by the standards of Mexico City, Curitiba, and Bogota.

BRT station in not-Boston

The BRT Report for Boston depicts another picture in that flavor on PDF-p. 14. It is also painfully misleading about existing BRT lines: its blurb about Mexico City omits the fact that the city has a large, expanding subway network with almost as much ridership as New York’s, and alongside Mexico; its blurb about Cleveland’s HealthLine BRT omits all the internal problems of the line, which make Cleveland urbanists denigrate it as a poor transportation solution.

BRT is a useful tool in cities’ kit for solving transportation problems. But proponents have to be honest about the tradeoffs involves: it is cheaper than a subway but also slower, less comfortable, and more expensive to operate; and it requires difficult choices about how to allocate street space. There are many examples of BRT on streets going down to about 30 meters, and Boston BRT could have also chosen to depict even narrower streets, to be relevant to Boston. Instead, it’s engaging in subterfuge: the report is claiming that BRT is faster than light rail and implying it’s the primary transit mode in Mexico City, and by the same token, the pictures all show wide enough streets for anything.

Core Connectors and In-Between Neighborhoods, Redux

Five years ago, I wrote about how American cities’ transit priorities cause them to underrate the neighborhoods with the best potential, which typically are also the poorer ones. Those are the in-between neighborhoods: beyond the gentrified core of the city, which is often within walking distance of the CBD in a small region, but not so far that they’re really suburbs. Instead of serving these neighborhoods, cities that want to look like they’re redeveloping build core connectors, i.e. short-range transit services within the gentrified (or gentrifying) center. I was specifically complaining about two plans, one in Providence and one in New Haven. The Providence plan involved a mixed-traffic streetcar, which has since been downgraded to a frequent bus. It’s this project that I wish to talk about in this post.

First, some background: in the 2000s and early 2010s, Rhode Island realigned I-195. This project, called Iway, rebuilt a segment of the freeway to higher standards, but also moved it so as to no longer cut off the Jewelry District from the CBD (called Downcity). Iway turned the Jewelry District from a post-industrial neighborhood to the next (possibly the only) frontier of gentrification in the city, and state elites needed to decide what to do with all this land. This led to plans to build what was in vogue in the late 2000s and early 2010s: a mixed-traffic streetcar, which would connect the Rhode Island Hospital and Jewelry District with Downcity and continue either north to the train station, or east to College Hill via the East Side Tunnel, a short bus-only tunnel cutting off a steep hill between Downcity and the Brown campus. This was from the start bad transit, and we in the Greater City community were skeptical. The plan was eventually scuttled, and the website’s registration lapsed without any redirect to the new plan, which is BRT.

The new BRT route is going between the train station and the Jewelry District. It’s planned to be very frequent, with a bus every 4-5 minutes, appropriate for the short length of the route, about 2 km between the hospital and the train station. The plan is to build open rather than closed BRT, with several branches interlining on the route. Overall, it looks like RIPTA is doing BRT right. And yet, it’s a terrible project.

The top bus corridor in Rhode Island is the R route (for Rapid), formed from the former 99 and 11 buses, which were by far the top two in ridership. It runs every 10 minutes, between Pawtucket and South Providence, serving some of the poorest parts of an already poor urban area. It has some BRT treatments, including hard-fought signal priority (Governor Carcieri vetoed it six times, and it took until the more progressive Lincoln Chafee replaced him for signal priority to go ahead). But buses run in mixed traffic, and fare collection is on-board. If any route deserves better frequency, it’s this one.

Moreover, the attempt to shoehorn multiple routes through the BRT path is compromising those routes. The R route is already detouring through the train station, which the old 99 route did not serve, and which forces a few minutes’ detour. Another bus, route 1, does not currently serve the train station, but will be rerouted once the BRT path opens; route 1 goes through the East Side tunnel, and making it detour to the train station would give it an especially circuitous path between the East Side and Downcity (the 1 already detours to enter the hospital, which is set back from the street). This, in turn, compromises the usefulness of the tunnel, which is that it interlines several routes between Downcity and Brown, which then go in different direction east of Brown.

There are potentially strong east-west corridors that could receive the R treatment. In the east, off-board fare collection on the buses using the tunnel would considerably speed up service. In the west, there are a few potentially strong routes: Broadway (carrying the 27 and 28 to Olneyville), Atwells in Federal Hill (carrying the 92 fake trolley, which runs through to the East Side and used to use the tunnel), and Westminster/Cranston (carrying the 17, 19, and 31). The highly-branched nature of the routes east of the tunnel makes through-service dicey, and this in turn is a matter of a broken bus network in East Providence. But overall, demand roughly matches that of the strongest corridor on the west, which is either Broadway or Westminster/Cranston, depending on how much branching one tolerates. This would create a second rapid bus trunk between College Hill and Olneyville. So why is the city investing in another route?

It’s not the train station. The train station itself is not a compelling transit destination. It’s too close to Downcity; even with a 5-minute bus frequency, it’s faster to walk from the central bus transfer point at Kennedy Plaza (or to the nearest point on the old 99 route on North Main or Canal) than to transfer to the right bus. It should be served by the routes for which it’s on the way, for example the northwest-bound 50, 56, and 57 routes. It’s unlikely anyone will transfer to a bus to the train station. Nor is it likely anyone will take the 1 from College Hill to the train station: walking downhill takes 15 minutes, and people going to a train station need more reliability than a mixed-traffic bus can provide. Walking uphill is more difficult, and there is less need for reliability, but even then, it seems that most people walk. This means the only real use of the train station connection is for people from the Jewelry District.

This brings me to the Jewelry District itself. The city wants to redevelop it, but it is not yet much of a destination. Nor is Providence itching for new development sites: residential rents are affordable on the East Side, and Downcity commercial property values are so low that the city’s tallest building is empty and was said at appraisal to have no value. So why the rush to give the Jewelry District better public transit than existing neighborhoods that direly need it, like South Providence, Olneyville, and Pawtucket?

The answer is contained in the title of this post. South Providence and Olneyville are in-between neighborhoods. Pawtucket is far enough away that it is getting a $40 million infill station on the Providence Line, but the state is not going to fund frequent service or integrated fares between the line and RIPTA buses. As far as Pawtucket’s predominantly poor and working-class residents are concerned, the train might as well not be there; nor will any gentrifiers move to Pawtucket for service to Boston (they get about the same travel time out of Providence and far better amenities). The focus for the city and the state is on redevelopment, and one can almost see the dollar signs in the eyes of the power brokers who passed this deal.

This neglect of the working class and of Providence’s nonwhite neighborhoods (South Providence is black, Olneyville is Hispanic) is not deliberate. But there is clear disparate impact: the Jewelry District gets BRT, South Providence and Olneyville can drop dead. Like everywhere else in the US, the power structure in Providence discourages investment in the in-between neighborhoods, even comfortable ones like the East Side. The in-between neighborhoods are intact enough that building something there is about providing transportation services, rather than about development and renaissance and the creative capital and other buzzwords. And providing services is too boring, too political, too underappreciated. Better to build something shiny and say “I did that,” even if it’s useless. What the elites consider shiny changes every few years – it was streetcars last decade and is frequent buses today – but the principle is the same: instead of investing for the benefit of residents of Providence and its inner suburbs, the state invests for the benefit of ribbon-cutters.

Rapid Transit in the Third World

Last month, I committed to producing a subway fantasy map for Lagos via a Twitter poll. I’m working on this, but before I go into Lagos itself, I want to talk about the third world in general. Good transportation in poor countries is of independent interest, but it also has some applications to thinking about solutions for rich countries, such as the countries my readers live in. The reason is that every principle of good transportation planning has edge cases, exceptions, and assumptions, and it is critical to evaluate these in the largest variety of situations. Understanding transportation in the United States can yield insights about Europe and vice versa; likewise, understanding the first world can yield insights about the third and vice versa.

The epistemological principle I use is that if I believe that a high concentration of factor A makes solution B work better, then a low concentration of factor A should make solution B work worse. I used that in a post about high-speed rail in Sweden, arguing against it due to the absence of factors that make it work better, namely, linear population distribution. Many good design principles formulated in rich countries depend on those countries’ high incomes, and are less relevant to countries that are only about as wealthy as the US and northwestern Europe were in 1900.

Everything is terrible

On nearly every indicator of technology or living standards, every poor country is worse than every rich country. There are some exceptions involving middle-income countries (for example, Russia and China have very good rail freight), but not in low-income countries. I wrote a piece in YIMBY recently describing the state of New York and Vienna in the early 20th century, which had very high crowding levels; much of the same story can describe many third-world cities today, especially in India, where tight zoning limits housing supply to the point of overcrowding. In Mumbai, the average residential floor space per person is 9 square meters, compared with 55 in Manhattan.

Pollution levels are very high as well, because of the combination of high population density and heavy industry (especially in North India), as well as the proliferation of cars. The amount of pollution caused by 50 or 100 cars per 1,000 people in a dense city where the cars don’t have catalytic converters can be many times worse than that caused by the 200 mostly diesel-powered cars per 1,000 people of Paris, or the 250 cars per 1,000 people of New York. The low motorization levels of lower-middle-income cities like Cairo, Lagos, or Mumbai aren’t a barrier to traffic, either: those cities routinely have traffic jams, just as the United States started having jams in the 1920s. These cities have centralized employment in the CBD, not a lot of road capacity coming in, and a culture in which the middle class drives (or is driven by chauffeurs).

This creates an urgency for improving public transportation in low-income countries that does not exist in the developed world. Third-world countries that build subways spend a much higher share of their GDPs on them than Europe and Japan do, and some, such as India and Bangladesh, spend more than the United States. If Paris hadn’t built the RER, Franciliens would drive or take the slower Metro; if Shanghai hadn’t built the Metro, Shanghainese would still be living in tiny apartments and riding buses in crawling traffic; if Lagos doesn’t build a metro, Lagosians will keep facing multi-hour commutes. The same situation also creates an urgency for improving other areas the government can invest in; good government, capable of making these investments at reasonable cost, without too much corruption, is crucial for economic and social development.

Concrete before electronics

The cost of advanced signaling systems, such as driverless technology, is approximately the same everywhere in the world, in exchange rate terms. The cost of civil infrastructure construction is approximately the same in PPP terms, and if anything may be a little lower in poor countries. The cost of labor that advanced technology avoids is proportional to wages. This means that the electronics-before-concrete principle is less valid in poorer countries, and is sometimes not valid at all. There are practically no driverless metros in developing countries; the only examples I can find of lines in operation include two lines in Sao Paulo and one in Manila, with a small handful more under construction. Brazil is middle-income, and the Philippines are lower-middle-income rather than poor.

This principle also extends to countries with existing rail lines that they could expand. Investments in concrete – additional tracks, grade separation, relief lines – are more valuable than in developed countries, while investments in electronics are less valuable. A city with a desperate transportation situation can expect that every rapid transit line it builds will fill quickly. Tunnels are in a way more future-proof than precise schedules and resignaling.

Regulate cars, not buses

A recurrent feature of transportation in poor cities without rapid transit or BRT is the minibus. It goes by various names; the most famous to the first-world reader is probably the Nairobi matatu, but it also exists in Lagos as the danfo, in the Philippines as the jeepney, and in Jakarta as the angkot. These vehicles are not popular with the segment of the population that the government listens to: they are typically noisy and dirty and the drivers are aggressive. The governor of Lagos State recently announced a plan to ban the danfos, saying they don’t meet the international standards of a great city and should be replaced with air-conditioned buses. This is while the city is still working on its first metro line.

In Delhi, attempts to give buses road priority met an intense backlash from high-income drivers. There was a failed lawsuit openly stating that car drivers’ time was more important. Eventually Delhi scrapped the system entirely.

In contrast, the most successful public transit in cities that were recently poor or low-income, such as Singapore or Seoul, is in an environment where state policy restrained cars and not buses. Singapore has had congestion pricing since in the 1970s, the first city in the world to implement this scheme, and levies high taxes on cars, as does Hong Kong. Seoul restrained domestic consumption, including of cars, in its period of early industrialization from the 1960s to the 1980s.

Nigeria has 60 cars per 1,000 people. Lagos has maybe 150. To a large majority of the city’s population, cars are traffic, not transportation. Numbers in other third-world megacities vary but are not too different: Cairo has about 200 as of 2011, Delhi about 170, Jakarta about 300. (Some car and population numbers are a few years out of date; caveat emptor.) Traffic restraint is the correct policy given massive traffic jams and growing pollution levels, and the sooner the city starts, the better it will look in a generation.

Plan for growth

Developing-world cities are going to be much larger and richer in 30 years than they are today. National population growth rates range from moderate in India and Bangladesh to explosive in Nigeria, Kenya, and Tanzania. Moreover, all of these countries have low urbanization rates today and fast migration from the villages to the cities, setting up fast urban population growth even where national population growth isn’t so high. Economic growth projections are dicier, but at least one estimate through 2024 is quite optimistic about India and East Africa.

The high-density context of most cities in question rules out any auto-based development pattern. The population density of the eastern half of the Indo-Gangetic Plain, from Delhi downriver to Bangladesh, is about 1,000 people per km^2, comprising nearly 600 million people. Nowhere in the developed world is this density seen outside city regions. Lombardy has 400 people per km^2, and is as hemmed by mountains as North India, producing large-scale thermal inversions; with high levels of car traffic and heavy industry, it is one of the most polluted regions of Europe. Southern Nigeria is not so dense, but with fast population growth, it eventually will be. Egypt’s population density along the Nile is well into the four figures.

This also has implications for how rapid transit should be built. A metro line that passes through lightly-populated areas will soon sprout dense development around it, just as the early lines did in late-19th century London and early-20th century New York. Most New York railfans are familiar with the photo of farmland next to the 7 train in the 1910s; between 1900 and 1930, New York’s population doubled, while Queens’ population grew by a factor of 7. Such growth rates are realistic for some developing-world cities. For the same reason, it is worthwhile investing in grade-separated rights-of-way now, when they are cheap.

Another implication concerns capacity. Even Nairobi, which is not a megacity, can expect to become one soon, and requires many different rapid transit lines entering its center. Some of these can be accommodated on existing roads, as els or relatively easy subways under wide streets, but not all can. When the roads are wide enough, cities should consider four-track structures, since the relative construction cost of four-tracking is low for an el or a cut-and-cover subway.

Four-tracking has one additional benefit: local and express service, which is of critical importance in the very largest cities. In forums like Skyscraper City, Tokyo railfans often express concerns over China’s subways, which have no express tracks and little to no commuter rail, since they offer no path through the center faster than about 35 km/h (Tokyo’s express commuter lines, like Tokaido and Yokosuka, approach 60 km/h).

The final implication is that it’s fine to build a central business district from scratch. Shanghai is doing this in Lujiazui, but that is the wrong location, on the wrong side of a riverbend, with only one Metro line serving it, the overcrowded east-west Line 2; a north-south rail line would have to cross the river twice. A better location would have been People’s Square, served by Lines 1, 2, and 8. This is of especial relevance to cities whose traditional center is in a difficult location, especially Lagos but also Dar es Salaam.

BRT is not rapid transit

The failure of Delhi’s BRT line is in some sense atypical. The line was compromised from the start, and global pro-BRT thinktank ITDP expressed criticism from the start. However, other BRT projects draw cause for concern as well. Dar es Salaam’s BRT is instructive: the first phase cost about $8.5 million per km in exchange rate terms, or about $27 million per km in PPP terms, comparable to an average European light rail line or to an American BRT boondoggle. A hefty chunk of this cost comes from importing Chinese-made buses, which are priced in exchange-rate terms and not in PPP terms.

All else being equal, higher incomes strengthen the case for rail vs. BRT and lower incomes weaken it, since one of the major advantages of rail is fewer drivers per unit of passenger capacity. However, there is a countervailing force: the bulk of the cost of rail construction is local construction, priced in PPP terms, and not imported capital, priced in exchange rate terms. Trains still cost more than buses per unit capacity, but the bulk of the cost premium of rail over BRT is not the vehicles, and a weak currency reduces this premium.

And for all of the global marketing, by ITDP and by Jaime Lerner, the Curitiba mayor who invented modern BRT, BRT is not rapid transit. It is surface transit, which can achieve comparable speed to a tramway, but in a dense city with heavy traffic, this is not high speed. The busiest Parisian tramways, T1 and T3, average about 18 km/h. Modern rapid transit starts at 30 km/h and goes up as construction standards improve and stop spacing widens. BRT is still a useful solution for smaller cities, but in the larger ones, which need more speed, grade-separated rapid transit is irreplaceable.

Don’t neglect mainline rail

How are people going to travel between Jakarta and Surabaya, or between Lagos and Kano, or between Nairobi and Mombasa? They’re not going to fly; the capacity of air traffic is not high. They’re not going to take a vactrain. The only real solution is a high-speed rail network; Indonesia is already building HSR from Jakarta to Bandung, using Chinese technology, with plans for a further extension to Surabaya.

The most difficult part of building a new intercity rail network from scratch is serving the big cities. This is the big advantage of conventional rail over maglev or vactrains: it can run on legacy tracks for the last few kilometers. (In poorer countries, which import technology from richer ones, another advantage is that conventional rail isn’t vendor-locked.) Between this and the need to also accommodate medium-speed intercity rail to smaller cities, it’s important that developing-world cities ensure they have adequate right-of-way for any future system. Trunks should have a minimum of four tracks, with intensive commuter rail service on the local tracks, in a similar manner to Mumbai.

It is also important to build the metro to be mainline-compatible, in electrification and track gauge. It is wrong for India (and Pakistan) to build a single kilometer of standard-gauge metro; everything should be broad-gauge. Russia, where everything is on Russian gauge, does this better. African mainline rail networks are usually narrow-gauge and weak, and in some places (such as East Africa) are being rebuilt standard-gauge. Southeast Asia runs the gamut, with reasonable service in Jakarta, which is running frequent electric commuter rail using second-hand Japanese trains; this suggests future metro lines in Jakarta should be built narrow- rather than standard-gauge, to allow Tokyo-style through-service to commuter rail.

Conclusion

The biggest developing-world cities have problems with air pollution, traffic, overcrowding, and long commutes – precisely the problems that rapid transit is good at solving. They have equally great problems with infrastructure for electricity, running water, and sewage, and with access to health care, education, and such basic consumer goods as refrigerators. And they have limited tax capacity to pay for it all.

This makes building good transit – cost-effective, future-proof, and convenient enough to get high ridership – all the more critical. The smallest cities today may be able to get away with looking like smog-ridden midcentury Los Angeles, but even medium-size ones need to plan on models starting from New York or London or Tokyo, and the biggest ones, especially Lagos, should plan on looking like something that doesn’t really exist today.

To that effect, third-world governments need to absorb massive amounts of knowledge of good practices developed in Western Europe and high-income East Asia (and to a lesser extent Russia and China). But they cannot implement them blindly, but have to learn how to adapt them to local conditions: chiefly low incomes, but also weak currencies, import-dependence in technology, high expected future growth, and (in many cases) high expected population density. Nothing prevents a poor country from doing transit well: China, still a middle-income country, has more high-speed rail ridership than the rest of the world combined, and subway ridership per capita in Beijing, Shanghai, and Guangzhou is healthy. But India, Pakistan, Nigeria, and other poor countries with big cities have their work cut out for them if they want to solve their transportation problems.