Category: Good Transit

Queens Bus Redesign

New York City Transit has just released its draft redesign for the Queens bus network. It’s a further-reaching reform than what was planned for the Bronx. I’m still seriously skeptical about a number of aspects, but this redesign is genuinely a step forward. The required changes are for the most part tweaks, with just one big change in concept.

What’s in the redesign?

The redesign goes over the local and express bus routes in Queens. I am not going to look at the changes to the express buses, which are not an important part of the network anyway; Queens has a total of 674,000 local bus passengers per weekday and only 15,000 express passengers.

The changes to the local buses include a from-scratch redesign of the network; four new color-coded brands for the local buses; stop consolidation depending on color coding, of which the tightest spacing proposed is 400 meters; and a list of priority corridors where buses are to get dedicated lanes. The scope is only the Queens buses, but there are some new Brooklyn connections: the Metropolitan and Flushing Avenue routes (the new QT3, QT4) keep running through, as they do today, but the Myrtle Avenue route, the current Q55 and new QT55, stops at Ridgewood with a forced transfer to the Brooklyn Myrtle Avenue route.

The four color-coded brands are an unusual, though not unheard of, system. There are four distinct brands among the redesigned Queens buses: blue, red, purple, green. Blue is essentially select bus service, retaining the long stop spacing (“over a mile”), potentially intersecting some bus routes without a transfer; the point is to connect high-demand areas like Flushing with Jamaica. The other three are for various regular local routes. Red routes are distinguished exclusively in having slightly wider stop spacing, 660 meters versus 450 for purple and 400 for green, but otherwise look similar on the network map. Purple and green routes are distinguished in that purple routes are branded for neighborhoods far from the subway and intended to get people from outlying points to subway stations.

What’s good about it?

Stop consolidation is important and I’m glad to see it get play in New York. The choice of interstation across the non-blue routes is solid and close enough to the theoretical optimum that the exact value should depend on ensuring every intersection has an interchange rather than on squeezing a few extra seconds of door-to-door trip time for non-transfer passengers.

The same goes for the decision to designate 21 corridors as top priorities for dedicated bus lanes. The plan does not promise bus lanes on all of them, since the ultimate decision is in the hands of NYCDOT and not the state-owned MTA/NYCT. But it does the best it can, by putting the proposal front and center and announcing that these corridors should be studied as candidates for bus priority. Most of the important streets in Queens are on the list; the only glaring omissions are Union Turnpike, Myrtle, and Metropolitan.

The above two points are not strictly about the redesign. This is fine. When Eric Goldwyn and I tried estimating the benefits of our Brooklyn bus redesign plan, we found that, taking speed, access time, and frequency into account, the redesign itself only contributed 30% of the overall improvement. Stop consolidation and bus lanes contributed 30% each, and off-board fare collection 10%. The Queens plan at the very least has stop consolidation, off-board fare collection as planned when the OMNY smartcard is fully rolled out, and partial use of bus lanes.

But the bus network as redesigned has notable positive features as well. There’s greater reliance on the full network, for one. The JFK AirTrain is free for passengers boarding at Lefferts Avenue or Federal Circle rather than at the subway connection points at Jamaica and Howard Beach, and so the Lefferts Avenue route to JFK, the current Q10 and future QT14, stops at the AirTrain station instead of going all the way to the terminals.

Elsewhere, the bus network is more regular, with fewer bends. The network does not assume away the borough’s important nodes: you can still figure out where Flushing and Jamaica are purely from looking at the map. But it does offer some routes that bypass these nodes for crosstown traffic, for example the redesigned QT65, straightening the current Q65.

What’s bad about it?

The four-color system is just bad. The blue routes are understandable but still bad: they split frequency, so that passengers living next to the local stations on shared routes like Main Street get poor service. The red-purple-green distinction is superfluous – the map really does not make it clear how a red route differs from the others, and the purple and green routes are really the same kind of local bus, just one with a distinguished node at a subway stop and one where there may be multiple distinguished nodes.

The frequencies offered are also weak. Some routes are proposed to run every 8 minutes all day, namely QT route numbers 6, 10, 11, 14, 15, 16, 17, 19, 20, 32, 52, 55, 58, 66, 69, 70. Exactly one is proposed to run more frequently, the QT44 every 5 minutes. The rest run every 10-12 minutes or worse. On weekends, even the 8-minute routes drop to 10-15 minutes. Many routes are quite peaky and there’s no easy distinction between routes for which the report proposes an all-day headway (including all the 8-minute ones above) and ones for which the report proposes separate peak and base headways; the purple routes in general look somewhat peakier than the others, but it’s not a consistent distinction.

If the frequencies are weak, then it means that either the buses are too slow, or there are too many route-km to split a fixed service-hours budget across. NYCT mistakenly thinks that bus costs scale with service-km rather than service-hours, so the planned speedups can in fact be spent on more frequency, but it’s not enough to create a vigorous frequent network. Some pruning is needed; overall the network seems very dense to me, even in areas with decent subway coverage.

A few individual routes are weak too – I don’t think the QT1 idea, paralleling the Astoria Line on 21st Street and then the G train to Downtown Brooklyn, is a good idea. There are two more north-south routes running through to Williamsburg, where the relevant buses are pretty weak and pruning is advisable in order to redeploy service-hours to areas with more demand. If there’s somehow money that can only be spent on north-south service through Williamsburg, it’s better to increase frequency on the G train, which is faster than any bus could ever be.

Is this redesign valuable, then?

Yes! Between the stop consolidation, partial installation of bus lanes, and some of the aspects of the new network, the proposal looks like a two-thirds measure, at worst. It can’t be a full measure because there are serious drawbacks to the plan, not just on the level of details (i.e. too much service to Williamsburg) but also on the conceptual level of the four distinct brands. But it is a noticeable improvement over the current system, and I expect that if it is implemented, even with its many current flaws, then Queens will see a serious increase in bus patronage.

Moreover, the flaws in the plan are not inherent to it. If someone showed me the bus map without the color coding, just with stops and frequencies, I would not even notice the red-green-purple distinction. The blue routes I would notice, and suggest be reduced to the usual stop spacing of everything else; but the others, I wouldn’t. So even the most fundamentally bad part of the plan can be jettisoned while retaining all the good. Everything else is a tweak, and I expect that tweaks will happen one way or another.

Right now comes the community meetings stage, in which existing riders who have too much time will yell, and potential riders who don’t currently take the bus because it’s too slow don’t show up at all. The plan will be tweaked, and the tweaks may well make it worse rather than better. But what good transit activists in New York say matters, and so far the reaction should be positive, demanding certain changes but keeping the gist of the redesign.

Outlying S-Bahn Tunnels

There’s a thread on Twitter by Stephen Smith bringing up Zurich’s S-Bahn as an alternative to extensive metro tunneling. It reminded me of something I’d been meaning to write about for a long time, about how S-Bahn tunnels, in Zurich and elsewhere, include not just the bare minimum for through-running but also strategic tunneling elsewhere to reach various destinations not on the mainline. Zurich’s S-Bahn includes about 19 km of tunnel built since the 1960s, which is similar per capita to the amount of tunneling built for the Washington Metro.

Such tunneling is important to ensure a regional rail network reaches destinations off the mainlines. Even cities with metro systems need to understand this as long as they have some mainline rail serving suburban destinations. For example, in the Center of Israel, Tel Aviv is getting a subway-surface light rail network, but outside the urban core rail transport will remain dominated by Israel Railways service; as Israel Railways avoids many city centers, such as Netanya, short strategic tunnels are critical.

Tunnels in Zurich

The core of the Zurich S-Bahn is three city center tunnels: the 2 km Käferberg Tunnel from Oerlikon to Hardbrücke, the 7 km combination of the Hirschengraben Tunnel and the Zürichberg Tunnel from Hauptbahnhof to the Right Bank of Lake Zurich and points northeast, and the 5 km Weinberg Tunnel from Hauptbahnhof to Oerlikon and points north. The Käferberg Tunnel is from the 1960s, the Hirschengraben and Zürichberg Tunnel opened in 1989-1990 as the core of the Zurich S-Bahn, and the Weinberg Tunnel opened in 2014 as a second S-Bahn route to add more capacity.

These 14 km of tunnel look like any standard picture of regional rail tunneling. However, Zurich has in addition built a 5 km tunnel for a loop to the airport. Without this tunnel, no regional or intercity rail service to the airport would have been possible, as the airport was at a distance from the mainline; only trams could have served the airport then.

In addition to these 19 km, there is some talk of building an additional tunnel of 7-10 km on the Zurich-Winterthur Line, called the Brüttener Tunnel, to speed up service between these two cities.

Tunnels on other regional rail systems

In Paris, the RER consists not just of legacy rail track and city center tunnels, but also outlying tunnels reaching new destinations. The RER B connection to Charles de Gaulle Airport is new construction, opening in 1976 as a commuter line just before the RER opened and incorporated it as a branch. It’s a mix of above- and underground construction, totaling 5.5 km of tunnel. Two more key RER lines, at both ends of the RER A, are new: the branch to Cergy, which opened between 1979 and 1994 and has 3 km of tunnel, and the branch to Marne-la-Vallée, which opened in stages starting on the same day as the RER A’s central tunnel and continuing until reaching its terminus in 1992.

All three new RER branches are busy. They have to be – if there weren’t so much demand for them, it would have been financially infeasible to build them and those areas would have had to make do with a bus connection to the existing mainlines. The Marne-la-Vallée branch carries about two thirds of the eastern branch ridership of the RER A, making it most likely the busiest single rail branch in Europe.

In London, the regional rail network is less modern than in Paris, Zurich, and other cities with extensive development of new tunnels. Nonetheless, the Crossrail plans do include a short outlying tunnel reaching Heathrow Airport. Moreover, one of the two eastern branches of the mainline has the characteristics of an outlying tunnel, namely the branch to Canary Wharf. Canary Wharf is only 5 km from the City of London and the tunnel connecting to it is contiguous with the central tunnel, but the branch is not really about improving connections to onward suburbs. Where La Défense was always on the way to western suburbs on the RER, Canary Wharf is only on the way to Abbey Wood. There are proposals among area railfans to extend this branch much farther to the east, but no official plans that I know of. In the currently planned paradigm for Crossrail, Canary Wharf is purely a destination.

In Munich, there is a new line toward the airport, with some tunneling on airport grounds as well as at two intermediate suburban stations. There is also a short above-ground spur connecting the airport to the western side of the S-Bahn, giving it two different routes to city center. Finally, there is a short tunnel slightly to the west of the main trunk tunnel to better connect S7 to the mainline.

Why are airports so prominent on this list?

The concept of using strategic tunnels to build new spurs and loops to connect mainlines to new destinations has nothing to do with airports. And yet, so many of these spurs connect to airports: Charles de Gaulle, Heathrow, Zurich, Munich. There are many more such examples, on regional or intercity lines: Schiphol, Arlanda, Ben-Gurion, soon-to-be Berlin-Brandenburg, Barajas. Why is that?

The answer is that the purpose of a spur or loop is to connect to a destination off the mainline. European cities for the most part developed around the railway or metro line. Virtually every important destination in London is on a legacy railway because during the city’s 19th and early 20th century growth period, the railway was the only way to get to Central London. Airports are consistent exceptions because they’re so land-intensive that it’s hard to site them near existing railways.

Where non-airport destinations somehow had to be developed away from the mainline, they’re attractive targets for spurs as well. Canary Wharf sits on the site of a disused dock, which generated some freight rail traffic but little demand for passenger rail. Cergy is one of several new towns built around Paris to act as suburban growth nodes, together with Marne-la-Vallée and Évry (served on a loop of the RER D).

In smaller cities than Paris and London, suburban growth often came together with a metro line. In Stockholm, the Metro was planned together with public housing projects, so many of the Million Program projects are right next to stations, facilitating high public transportation usage. There’s usually no need to build many new regional rail spurs, because such sites are close enough to the center for metro service to be quick enough.

The situation of regional rail in Israel

In Israel, urban development has ignored the railway almost entirely. The colonial network was weak and barely served the state’s travel needs. Investment was minimal, as the state’s political goals were population dispersal and Judaization of peripheral areas rather than efficient transportation. Towns were built around the road network, connected to one another by bus since people were too poor to afford cars.

Rail revival began in the early 1990s with the opening of the Ayalon Railway, providing through-service between points north and south of Tel Aviv. In the generation since, ridership has grown prodigiously, albeit from low initial levels, and the state has built new lines, with an ongoing project to electrify most of the passenger network. However, since the cities came first and the trains second, the new lines do not enter city centers, but rather serve them peripherally near the highway, often surrounded by parking.

Thus, Netanya’s train station is located to the east of the city’s built-up area, on the wrong side of the Route 2 freeway. Ashdod’s train station is on the periphery at a highway interchange, well to the east of city center. Ashkelon’s station is on the eastern margin. The under-construction line through Kfar Saba and Ra’anana passes just south of the built-up area.

In all of these cases, doing it right would require, or would have required, just short, strategic elevated or underground lines:

  • Netanya is at the northern end of the Tel Aviv commuter rail network, and so it can easily be served by a spur. The existing station can be retained as a junction for intercity rail service, but building a commuter rail spur would not compromise frequency. Such a spur would require no more than 2 km of tunnel.
  • In Ashdod and Ashkelon, there are north-south arterials that are so wide, 50-60 meters, that they could host cut-and-cover subways, effectively moving the line to the west to serve those cities better. In Ashdod there is a decision between going under B’nai Brith, which offers a more convenient through-route, and Herzl, which is more central but requires some boring at the southern end of the city.
  • In Kfar Saba and Ra’anana, about 8 km of tunnel under Weizmann and Ahuza are needed, and could potentially be done cut-and-cover as well, but these streets are 30 meters rather than 50 meters wide. Such a route would replace the under-construction combination of a freeway and railway.
  • In Rishon LeZion, a 6km route, not all underground, is needed to connect Rishonim with Moshe Dayan via city center and the College of Management rather than via the under construction freeway route avoiding these destinations.

Unfortunately, so far the state’s investment plans keep skirting city centers. It serves them with a cars-and-trains paradigm, which assumes the rail passenger is driving or riding a bus to the train station, never mind that in that case it’s more convenient to drive all the way to one’s destination. This suppresses ridership; not for nothing, the busiest station outside metropolitan centers is Rehovot, with 2.1 million annual entries, and not Ashdod, which is second with 1.9 million. Ashdod is a city of 220,000 and Rehovot one of 140,000, but Rehovot’s station is far more walkable. Were Ashdod not poor, few people would use the station at all – they’d all just drive.

On Envying Canada

In England and Wales, 15.9% of workers get to work on public transport, and in France, 14.9% do. In Canada, the figure is close: 12.4%, and this is without a London or Paris to run up the score in. Vancouver is a metro region of 2.5 million people and 1.2 million workers, comparable in size to the metropolitan counties in England and to the metro area of Lyon; at 20.4%, it has a higher public transport modal share than all of them, though it is barely higher than Lyon with its 19.9% share. Calgary, Ottawa, Edmonton, and Winnipeg are likewise collectively respectable by the standards of similar-size French regions, such as the departments of Bouches-du-Rhône (Marseille), Alpes-Maritimes (Nice), Gironde (Bordeaux), Haute-Garonne (Toulouse), and Bas-Rhin (Strasbourg).

As a result, Jarrett Walker likes telling American cities and transit agencies to stop envying Europe and start envying Canada instead. Canada is nearby, speaks the same language, and has similar street layout, all of which contribute to its familiarity to Americans. If Europe has the exotic mystique of the foreign, let alone East Asia, Canada is familiar enough to Americans that the noticeable differences are a cultural uncanny valley.

And yet, I am of two minds on this. The most consistent transit revival in Canada has been in Vancouver, whose modal share went from 14.3% in 1996 to 20.4% in 2016 – and the 2016 census was taken before the Evergreen extension of the Millennium Line opened. TransLink has certainly been doing a lot of good things to get to this point. And yet, there’s a serious risk to Canadian public transport in the future: construction costs have exploded, going from Continental European 15 years ago to American today.

The five legs of good transit

I was asked earlier today what a good political agenda for public transportation would be. I gave four answers, like the four legs of a chair, and later realized that I missed a fifth point.

  1. Fuel taxes and other traffic suppression measures (such as Singapore and Israel’s car taxes). Petrol costs about €1.40/liter in Germany and France; diesel is cheaper but being phased out because of its outsize impact on pollution.
  2. Investment in new urban and intercity lines, such as the Madrid Metro expansion program since the 1990s or Grand Paris Express. This is measured in kilometers and not euros, so lower construction costs generally translate to more investment, hence Madrid’s huge metro network.
  3. Interagency cooperation within metropolitan regions and on intercity rail lines where appropriate. This includes fare integration, schedule integration, and timetable-infrastructure integration.
  4. Urban upzoning, including both residential densification in urban neighborhoods and commercialization in and around city center.
  5. Street space reallocation from cars toward pedestrians, bikes, and buses.

We can rate how Canada (by which I really mean Vancouver) does on this rubric:

  1. The fuel tax in Canada is much lower than in Europe, contributing to high driving rates. In Toronto, gasoline currently costs $1.19/liter, which is about €0.85/l. But Vancouver fuel taxes are higher, raising the price to about $1.53/l, around €1.06/l.
  2. Canadian construction costs are so high that investment in new lines is limited. Vancouver has been procrastinating building the Broadway subway to UBC until costs rose to the point that the budget is only enough to build the line halfway there.
  3. Vancouver and Toronto both have good bus-rapid transit integration, but there is no integration with commuter rail; Montreal even severed a key commuter line to build a private driverless rapid transit line. In Vancouver, bus and SkyTrain fares have decoupled due to political fallout from the botched smartcard implementation.
  4. Vancouver is arguably the YIMBYest Western city, building around 10 housing units per 1,000 people every year in the last few years. Toronto’s housing construction rate is lower but still respectable by European standards, let alone American ones.
  5. There are bike lanes but not on the major streets. If there are bus lanes, I didn’t see any of them when I lived in Vancouver, and I traveled a lot in the city as well as the suburbs.

Vancouver’s transit past and future

Looking at the above legs of what makes for good public transport, there is only one thing about Canada that truly shines: urban redevelopment. Toronto, a metro area of 6 million people, has two subway mainlines, and Montreal, with 4 million people, has 2.5. Vancouver has 1.5 lines – its three SkyTrain mainlines are one-tailed. By the same calculation, Berlin has 6.5 U- and 3 S-Bahn mainlines, and Madrid has 2 Cercanías lines and 7 metro lines. Moreover, high construction costs and political resistance from various GO Transit interests make it difficult for Canadian cities to add more rapid transit.

To the extent Vancouver has a sizable SkyTrain network, it’s that it was able to build elevated and cut-and-cover lines in the past. This is no longer possible for future expansion, except possibly toward Langley. The merchant lawsuits over the Canada Line’s construction impacts have ensured that the Broadway subway will be bored. Furthermore, the region’s politics make it impossible to just build Broadway all the way to the end: Surrey has insisted on some construction within its municipal area, so the region has had to pair half the Broadway subway with a SkyTrain extension to the Langley sprawl.

Put in other words, the growth in Vancouver transit ridership is not so much about building more of a network, but about adding housing and jobs around the network that has been around since the 1980s. The ridership on the Millennium and Canada Lines is growing but remains far below that on the Expo Line. There is potential for further increase in ridership as the neighborhoods along the Canada Line have finally been rezoned, but even that will hit a limit pretty quickly – the Canada Line was built with low capacity, and the Millennium Line doesn’t enter Downtown and will only serve near-Downtown job centers.

Potemkin bus networks

When Jarrett tells American cities to envy Canada, he generally talks about the urban bus networks. Toronto and Vancouver have strong bus grids, with buses coming at worst every 8 minutes during the daytime off-peak. Both cities have grids of major streets, as is normal for so many North American cities, and copying the apparent features of these grids is attractive to American transit managers.

And yet, trying to just set up a bus grid in your average American city yields Potemkin buses. Vancouver and Toronto have bus grids that rely on connections to rapid transit lines. In both cities, transit usage is disproportionately about commutes either to or from a city core defined by a 5 kilometer radius from city hall. Moreover, the growth in public transport commuting in both cities since 1996 has been almost exclusively about such commutes, and not about everywhere-to-everywhere commutes from outside this radius. Within this radius, public transportation is dominated by rail, not buses.

The buses in Toronto and Vancouver have several key roles to play. First, as noted above, they connect to rapid transit nodes or to SeaBus in North Vancouver. Second, they connect to job centers that exist because of rapid transit, for example Metrotown at the eastern end of Vancouver’s 49. And third, there is the sui generis case of UBC. All of these roles create strong ridership, supporting high enough frequency that people make untimed transfers.

But even then, there are problems common to all North American buses. The stop spacing is too tight – 200 meters rather than 400-500, with frequency-splitting rapid buses on a handful of very strong routes like 4th Avenue and Broadway. There is no all-door boarding except on a handful of specially-branded B-line buses. There are no bus lanes.

One American city has similar characteristics to Toronto and Vancouver when it comes to buses: Chicago. Elsewhere, just copying the bus grid of Vancouver will yield nothing, because ultimately nobody is going to connect between two mixed-traffic buses that run every 15 minutes, untimed, if they can afford any better. In Chicago, the situation is different, but what the city most needs is integration between Metra and CTA services, which requires looking at European rather than Canadian models.

Is Canada hopeless?

I don’t know. The meteoric rise in Canadian subway construction costs in the last 15 years has ensured expansion will soon grind to a halt. Much of this rise comes from reforms that the Anglosphere has convinced itself improve outcomes, like design-build and reliance on outside consultants; in that sense, the US hasn’t been copying Canada, but instead Canada has been copying the US and getting American results.

That said, two positive aspects are notable. The first is very high housing and commercial growth in the most desirable cities, if not in their most exclusive neighborhoods. Vancouver probably has another 10-20 years before its developable housing reserves near existing SkyTrain run out and it is forced to figure out how to affordably expand the network. Nowhere in Europe is housing growth as fast as in Metro Vancouver; among the cities for which I have data, only Stockholm comes close, growing at 7-8 net units per 1,000 people annually.

Moreover, with Downtown Vancouver increasingly built out, Vancouver seems to be successfully expanding the CBD outward: Central Broadway already has many jobs and will most likely have further commercial growth as the Millennium Line is extended there. Thus, employers that don’t fit into the Downtown Vancouver peninsula should find a home close enough for SkyTrain, rather than hopping to suburban office parks as in the US. Right now, the central blob of 100 km^2 – a metric I use purely because of limitations on French and Canadian data granularity – has a little more than 30% of area jobs in Vancouver, comparable to Paris, Lyon, New York, Boston, and San Francisco, and ahead of other American cities.

The second aspect is that Canadians are collectively a somewhat more internationally curious nation than Americans. They are more American than European, but the experience of living in a different country from the United States makes it easier for them to absorb foreign knowledge. The reaction to my and Jonathan English’s August article about Canadian costs has been sympathetic, with serious people with some power in Toronto contacting Jonathan to figure out how Canada can improve. The reaction I have received within the United States runs the gamut – some agencies are genuinely helpful and realize that they’ll be better off if we can come up with a recipe for reducing costs, others prefer to obstruct and stonewall.

My perception of Canadian politics is that even right-populists like Doug Ford are more serious about this than most American electeds. In that sense, Ford is much like Boris Johnson, who could move to Massachusetts to be viceroy and far improve governance in both Britain and Massachusetts. My suspicion is that this is linked to Canada’s relatively transit-oriented past and present: broad swaths of the Ontarian middle class ride trains, as is the case in Outer London and the suburbs of Paris. A large bloc of present-day swing voters who use public transport is a good political guarantee of positive attention to public transport in the future. American cities don’t have that – there are no competitive partisan elections anywhere with some semblance of public transportation.

These two points of hope are solid but still run against powerful currents. Toronto really is botching the RER project because of insider obstruction and timidity, and without a strong RER project there is no way to extend public transportation to the suburbs. Vancouver is incapable of concentrating resources where they do the most good. And all Canadian cities have seen an explosion in costs. Canadians increasingly understand the cost problem, but it remains to be seen whether they can fix it.

The Brooklyn Bus Redesign is Out!

Marron just published my and Eric Goldwyn’s Brooklyn bus redesign proposal (with many thanks to Juliet Eldred for doing the graphics and design). The substance isn’t really changed from what we discussed last year. The delay in publication has had a few causes, of which I believe the biggest is that I completely missed that the links to many of the references in the lit review were dead and thus could not be typeset.

Instead of retyping an old blog post, I want to emphasize a few things that have come up in the last year. Some are specific to New York, others more general within the US. The idea of a bus redesign, introduced to the American discourse by Jarrett at the beginning of this decade, has gotten steadily more popular, and New York is beginning its own process, starting with the Bronx; in that context, it’s worthwhile pointing out specifics that Eric and I have learned from the Brooklyn process.

The redesign is a process, not a one-and-done program

Cities change. The point of a bus redesign is to let the bus network reflect the city of today and not that of when bus routes were set, typically when the streetcars were removed in the postwar era. The upshot is that the city can expect to change in the future, which means further bus redesigns may be necessary.

Instead of letting bus networks drift away from serving the city as is and doing a big redesign once in a generation, cities should change buses on an ongoing basis. American transit agencies are learning the principles of bus redesign this decade. They can and should use these principles for forward planning, tweaking bus routes as needed. Any of the following changes can trigger small changes in bus service:

  • New development
  • Shifts in commuting patterns even without new development
  • Changes in traffic patterns
  • Changes in the urban rail network
  • Long-term changes in driver labor, maintenance, etc.
  • Changes in bus technology, such as ride quality, dispatching, or pollution levels

In New York, the biggest ongoing change is probably the urban rail network. There are no subway extensions planned for Brooklyn, but there is expansion of subway accessibility, which changes the optimal bus network since some buses, like the B25 and B63, have no reason to exist if the subway lines they parallel are made accessible. There has been extensive activism about priorities here. To its credit, the MTA is accelerating accessibility retrofits, even though construction costs are extremely high.

New York’s current redesign process is flawed

Eric and I have heard negative feedback from various people involved in the process. Some are planners. One is a community activist, enough of a railfan and busfan not to NIMBY changes for the sake of NIMBYism, but nonetheless disaffected with how the Bronx redesign went.

As far as I can tell, the problem with the current process is that it’s too timid. In the Bronx, this timidity is understandable. The borough’s bus network is mostly good enough. The most important change in the Bronx is to speed up the buses through off-board fare collection, stop consolidation, bus lanes on main streets, and conditional signal priority, and plug the extra speed into higher frequency.

The MTA treats it as part of a separate process – select bus service (“SBS”) – and even though planning these two aspects separately is workable, the MTA does not understand that they are related and that speedups provide crucial resources for higher frequency. The problem here is with operating cost estimation. Like the other American agencies where I’ve asked, the MTA assumes bus costs scale with service-km, and thus higher speeds don’t change frequency. In reality, bus costs, dominated by driver wages, scale with service-hours. Higher speeds can be plugged one-to-one into higher frequency. In Brooklyn, only 30% of the benefits we estimate come from changing the network, and the other 70% come from speeding up the buses.

But Brooklyn is not the Bronx. The Bronx is largely good enough, in ways Brooklyn isn’t. Brooklyn is not terrible, but the bus network has too many circuitous or duplicative routes. Eric and I have consolidated about 530 km of bus route down to 350, without any of the coverage vs. ridership tradeoffs common to areas with less isotropic population density than Brooklyn. The MTA needs to be bolder in Brooklyn, and even bolder than that in Queens, if the redesign is to succeed.

The 14th Street bus lane

Eric and I encountered some political resistance to the idea of mass installation of bus lanes. Local interests listen to people with local connections, who are usually drivers. Transit riders are disproportionately riding to city center jobs, and have citywide rather than local political identities. When I went to an Open New York meeting, people began with a round of introductions in which people say their names and where they live, and the about 20 attendees represented maybe 15 different city neighborhoods. The upshot is that like Open New York’s mission of building more housing, the mission of diverting scarce street space from drivers to bus riders is best done on a citywide rather than street-by-street basis.

There is some hope of such a transformation happening. The bus lane on 14th Street survived a nuisance lawsuit, and ridership rose 17% almost immediately after it opened. The success is stark enough that a citywide increase in installation is plausible. City council speaker Corey Johnson promised to install 48 km of bus lane per year were he to be elected mayor, which is too passive but could do some good on the busiest routes.

Little Things That Matter: Jerk

When you ride a subway train, and the train decelerates to its station, you feel your body pulled forward, and your muscles tense to adjust, but then when the train reaches a sudden stop, you are suddenly flung backward, since you are no longer decelerating, but your muscles take time to relax and stop fighting a braking that no longer exist. This effect is called jerk, and is defined to be change in acceleration, just as acceleration is change in speed and speed is change in position. Controlling jerk is crucial for a smooth railway ride. Unfortunately, American mainline rail is not good at this, leading to noticeable jolts by passengers even though speed limits on curves and acceleration rates are very conservative.

This is particularly important for speeding up mainline trains around New York and other legacy cities in the US, like Boston. Speeding up the slowest segments is more important than speeding up the fastest ones; my schedules for New York-New Haven trains, cutting trip times from 2:09 to 1:24, save 4 minutes between Grand Central and 59th Street just through avoiding slowdowns in the interlocking. The interlocking is slow because the switches have very conservative speed limits relative to curve radius (that is, lateral acceleration), which in turn is because they are not designed with good lateral jerk control. The good news is that replacing the necessary infrastructure is not so onerous, provided the railroads know what they need to do and avoid running heavy diesel locomotives on delicate infrastructure.

Spirals and jerk

In practice, the worst jerk is usually not forward or backward, except in the last fraction of a second at the end of acceleration. This is because it takes about a second for train motors to rev up, which controls jerk during acceleration. Rather, the worst is sideways, because it is possible to design curves that transition abruptly from straight track, on which there is no lateral acceleration, to curved track, on which there is, in the form of centrifugal force centripetal force.

To reduce jerk, the transition from straight track to a circular arc is done gradually. There are a number of usable transition curve (see Romain Bosquet’s thesis, PDF-p. 36), but the most common by far is called the clothoid, which has the property of having constant change in curvature per unit of arc length – that is, constant jerk. Different countries have different standards for how long the clothoid should be, that is what the maximum lateral jerk is. Per Martin Lindahl’s thesis, the limit in Sweden is 55 mm/s (PDF-p. 30) and that in Germany is 69.44 mm/s (PDF-p. 38), both measured in units of cant deficiency; in SI units, this is 0.367 m/s^3 and 0.463 m/s^3 respectively. In France, the regular limit is 50 mm/s (Bosquet’s thesis, PDF-p. 35), that is 0.333 m/s^2, but it is specifically waived in turnouts.

Track switches are somehow accepted as sites of very high jerk. A presentation about various technical limits in France notes on p. 106 that in switches (“appareils de voie” or “aiguilles” or “aiguillages,” depending on source, just like “switch” vs. “turnout” in English), the jerk can be increased to 100 and even 125 mm/s. On p. 107 it even asserts that in exceptional circumstances, abrupt change in cant deficiency of up to 50 mm on main track and 100 on the diverging direction on a switch is allowed; see also PDF-pp. 13-15 of a pan-European presentation. Abrupt changes are not good for passengers, but will not derail a train.

Turnout design in the advanced world

Second derivative control, that is acceleration and cant deficiency, can be done using calculus and trigonometry tools. Third derivative control, that is clothoids and jerk, requires numerical calculations, but fortunately they are approximated well by pretending the clothoid is half straight line, half circular arc, with the length determined by the maximum jerk. Working from first principles, it’s possible to figure out that at typical turnout needs – e.g. move a train from one track to a parallel track 4 meters away – the clothoid is far longer than the curve itself, and at 50 mm/s jerk and 150 mm cant deficiency it’s not even possible to hit a curve radius of 250 meters.

Turnouts are inherently compromises. The question is just where to compromise. Here, for example, is a French turnout design, in two forms: 0.11 and 0.085. The numbers denoting the tangent of the angle at the frog, and the radius is proportional to the inverse square of the number, thus the speed is proportional to the inverse of the number. The sharper turnout, the 0.11, has a radius of 281 meters, a maximum speed of 50 km/h, and a total length of 26 meters from point to frog (“lead” in US usage), of which the clothoid curve (“point”) takes up 11, to limit jerk to 125 mm/s at a cant deficiency of 100 mm. The 0.085 turnout has a radius of 485 meters, a maximum speed of 65 km/h, a lead of about 38 meters, and a point of about 14.5 meters.

In Germany, turnouts have somewhat independent numbers and radii – some have shorter leads than others. The numbers are the inverse of those of France, so what France calls 0.11, Germany calls 1:9, but at the end of the day, the curve radius is the important part, with a cant deficiency of 100 mm. A higher cant deficiency may be desirable, but lengthening the point requires almost as much space as just increasing the curve radius, so might as well stick with the more comfortable limits.

Turnout design in the United States

American turnouts look similar to French or German ones, at first glance. I’ve seen a number of different designs; here’s one by CSX, on PDF-pp. 22 (#8) and 24 (#10), the numbers being very roughly comparable to German ones and inverses of French ones. CSX’s #10 has a curve radius of 779.39′, or 238 meters, and a lead of 24 meters, both numbers slightly tighter than the French 0.11. The radius is proportional to the square of the number, and so speed is proportional to the number.

However, the cant deficiency is just 50 mm. The point is not always curved; Amtrak’s low-number switches are not, so the change in cant deficiency is abrupt. Judging by what I experience every time I take a train between New York and New Haven, Metro-North’s switches have abrupt change in cant deficiency even on the mainline. The recommended standards by AREMA involve a curved point, but the point is still much shorter than in France (19.5′, or just under 6 meters, on a #12), so a 125 mm/s jerk only gets one up to about 62 mm cant deficiency.

The reason for this is that European turnouts are curved through the frog, whereas American ones are always straight at the frog. Extremely heavy American freight trains do not interact well with curved frogs and long points.

One might ask, why bother with such turnout design on rail segments that never see a heavy freight locomotive or 130-ton freight car? And on segments that do see the odd freight locomotive, like the approaches to Grand Central and Penn Station with the rare dual-mode locomotive, why not kick out anything that doesn’t interact well with advanced track design? Making a handful of passengers transfer would save around 4 minutes of trip time on the last mile into Grand Central alone for everyone else, not to mention time savings farther up the line.

Fare Evasion

There’s a moralistic discourse in the United States about fare evasion on public transport that makes it about every issue other than public transport or fares. It’s a proxy for lawlessness, for police racism, for public safety, for poverty. In lieu of treating it as a big intra-urban culture war, I am going to talk about best practices from the perspective of limiting revenue loss to a minimum.

This is an issue where my main methodology for making recommendations for Americans – looking at peer developed countries – is especially useful. The reason is that Americans practically never look at other countries on hot-button culture war issues, even less than (say) the lip service the center-left pays to foreign universal health care systems. Americans who support immigration liberalization practically never listen when I try bringing up the liberal work visa, asylum, and naturalization policies of Germany or Sweden. Knowing stuff about the rest of the world is a type of competence, and competence is not a factor in a culture war. The upshot is that successful policies regarding fare collection in (for example) Germany are obscure in the United States even more than policies regarding wonkier transportation issues like train frequency.

The current situation in New York

In the summer, Governor Cuomo announced a new initiative to hire 500 cops to patrol the subway. The justification for this scheme has varied depending on who was asking, but the primary goal appears to be to defeat fare evasion. Per Cuomo’s office, fare evasion costs $240 million a year on the subway and buses, about 5% of total revenue. The MTA has also mentioned a higher figure, $300 million; I do not know if the higher figure includes just urban transit or also commuter rail, where conductors routinely miss inspections, giving people free rides.

But New York fare evasion is mostly a bus problem: the rate on buses is 22%. On the subway the rate is only 4%, and there is somewhat more revenue loss on buses than on subways. This, in turn, is because bus fares are enforced by drivers, who for years have complained that fare disputes lead to assaults on them and proposed off-board fare collection as an alternative. On many buses, drivers just let it go and let passengers board without paying, especially if nearly all passengers are connecting from the subway and therefore have already paid, as on the B1 between the Brighton Beach subway station and Kingsborough Community College or on the buses to LaGuardia.

So realistically the subway fare evasion level is closer to $110 million a year. The total cost of the new patrol program is $56 million in the first year, escalating by 8% annually thanks to a pre-agreed pay hike scale. Whereas today the program is a net revenue generator if it halves subway fare evasion, a level that already seems strained, within ten years, assuming normal fare escalation, it will need to cut fare evasion by about 90%, which is a complete fantasy. A sizable proportion of riders who do not pay would just stop riding altogether, for one. The governor is proposing to spend more on fare enforcement than the MTA can ever hope to extract.

The American moral panic about fare evasion regrettably goes far beyond New York. Two years ago, BART announced that it would supplement its fare barriers with proof-of-payment inspections, done by armed cops, and lied to the public about the prevalence of such a belts-and-suspenders system. More recently, it trialed a new turnstile design that would hit passengers in the face, but thankfully scrapped it after public outcry. Boston, too, has its moral panic about fare evasion, in the form of campaigns like the Keolis Ring of Steel on commuter rail or Fare is Fair.

There is another way

In talking to Americans about fare evasion, I have found that they are generally receptive to the idea of minimizing revenue loss net of collection costs. However, what I’ve encountered more resistance about is the idea that people should just be able to walk onto a bus or train.

In the urban German-speaking world, everyone with a valid fare can walk onto a bus, tram, or train without crossing fare barriers or having to pay a driver. This system has been copied to American light rail networks, but implementation on buses and subways lags (except on San Francisco buses). In New York, the SBS system uses proof of payment (POP), but passengers still have to validate fares at bus stops, even if they already have paid, for example if they have a valid monthly pass.

In the vast majority of cities, no excuse exists to have any kind of overt fare control. Tear down these faregates. They are hostile to passengers with disabilities, they cost money to maintain, they constrain passenger flow at busy times, and they don’t really save money – evidently, New York’s subway fare evasion rate is within the range of Berlin, Munich, and Zurich. Fare enforcement should be done with POP alone, by unarmed civilian inspectors, as in Berlin. Some people will learn to dodge the inspectors, as is the case in Berlin, and that’s fine; the point is not to get fare evasion to 0%, but to the minimum level net of enforcement costs.

New York itself may have an excuse to keep the faregates: its trains are very crowded, so peak-hour inspections may not be feasible. The question boils down to how New York crowding levels compare with those on the busiest urban POP line, the Munich S-Bahn trunk. But no other American city has that excuse. Tear down these faregates.

What’s more, the fare inspection should be a low-key affair. The fine in Berlin is €60. In Paris on the RER I can’t tell – I believe it’s three figures of which the first is a 1. Inspectors who can’t make a citation without using physical violence should not work as inspectors.

Make it easy to follow the law

The most important maxim when addressing a low-level crime is to make it easy to follow the law. Mistakes happen; I’ve accidentally fare-dodged in Berlin twice, only realizing the error at the end of the trip. This is much more like parking violations or routine mistakes in tax filing.

The turnstile acts as a reminder to everyone to pay their fare, since it’s not possible to fare-dodge without actively jumping it. (I did turnstile-jump in Paris once, with a valid transfer ticket that the turnstile rejected, I think because Paris’s turnstile and magnetic ticket technology is antediluvian.) However, turnstiles are not necessary for this. A better method is to ensure most passengers have prepaid already, by offering generous monthly discounts. My fare dodges in Berlin happened once before I got monthlies and once on my way to the airport on my current trip, in a month when I didn’t get a monthly since I was only in Berlin 6 days.

New York does poorly on the metric of encouraging monthlies. Passengers need to swipe 46 times in a 30-day period to justify getting a monthly pass rather than a pay-per-ride. This is bad practice, especially for passengers who prefer to refill at a ticketing machine rather than at home or on their phone with an app, since it means passengers visit the ticketing machines more often, requiring the agency to buy more to avoid long lines. In Berlin, the breakeven point is 36 trips. In Zurich, it’s 20 trips; ZVV does whatever it can to discourage people from buying single tickets. In both cities, there are further discounts for annual tickets.

Unfortunately, the problem of indifference to monthlies on urban rail is common around the Anglosphere. Singapore has no season passes at all. In Vancouver, Cubic lobbying and a New Right campaign about fare evasion forced TransLink to install faregates on SkyTrain, and when the faregate project had predictable cost overruns, the campaigners took that as evidence the agency shouldn’t get further funding. London’s fare capping system is weekly rather than monthly – there are no monthly passes, and all fares are set at very high levels. Britain generally overuses faregates, for example on the commuter trains in London. London generally gives off an impression of treating everyone who is not a Daily Mail manager as a criminal. Paris is better, but not by much. The German-speaking world, as irrational as Britain and France about urban crime rates that are far lower than they were a generation ago, still treats the train and bus rider as a law-abiding customer unless proven otherwise.

Social fares

American transit agencies and activists resist calls for large monthly discounts, on a variety of excuses. The most common excuse is revenue loss, which is weird since realistically New York would transition to a large discount through holding the monthly fare constant and hiking the single-ride fare. It’s the second most common excuse that I wish to deal with here: social fares, namely the fact that many low-income riders don’t have the savings to prepay for an entire month.

On social fares, as on many other socioeconomic issues, it is useful for Americans to see how things work in countries with high income compression and low inequality under the aegis of center-left governments. In Paris, various classes of low-income riders, such as the unemployed, benefit from a solidarity fare discount of 50-75%. In both Paris and Stockholm, the monthly pass is flat regionwide, an intentional program of subsidizing regular riders in the suburbs, which are on average poorer than the city.

The flat fare is not really applicable to American cities, except possibly the Bay Area on BART. However, the large fare reductions to qualifying low-income riders are: a number of cities have used the same definition, namely Medicaid eligibility, and give steep discounts for bikeshare systems. On the same principle, cities and states can discount fares on buses and trains.

The right way to view fares

Fares are an important component of public transport revenue; the taxes required to eliminate fares are significant enough that there are probably better uses for the money. By the same token, the issue of fare evasion should be viewed from the lens of revenue loss, rather than that of crime and disorder. The transit agency is not an individual who is broken by being mugged of $100; it should think in terms of its own finances, not in terms of deterrence.

Nor is making it easier to follow the law going to encourage more crime – to the contrary. Transit agencies should aim at a fare system, including enforcement, that allows passengers to get on and off trains quickly, with minimum friction. Turnstiles do not belong in any city smaller than about 10 million people. The fare structure should then encourage long-term season passes, including annual passes, so that nearly all residents who take public transport have already paid. Random inspections with moderate fines are the layer of enforcement, but the point is to make enforcement largely unneeded.

And tear down the faregates.

Circumferential Lines and Express Service

In a number of large cities with both radial and circumferential urban rail service, there is a curious observation: there is express service on the radial lines, but not the circumferential ones. These cities include New York, Paris, and Berlin, and to some extent London and Seoul. Understanding why this is the case is useful in general: it highlights guidelines for urban public transport design that have implications even outside the distinction between radial and circumferential service. In brief, circumferential lines are used for shorter trips than radial lines, and in large cities connect many different spokes so that an express trip would either skip important stations or not save much time.

The situation

Berlin has three S-Bahn trunk lines: the Ringbahn, the east-west Stadtbahn, and the North-South Tunnel. The first two have four tracks. The last is a two-track tunnel, but has recently been supplemented with a parallel four-track North-South Main Line tunnel, used by regional and intercity trains.

The Stadtbahn has a straightforward local-express arrangement: the S-Bahn uses the local tracks at very high frequency, whereas the express tracks host less frequent regional trains making about half as many stops as well as a few intercity trains only making two stops. The north-south system likewise features very frequent local trains on the S-Bahn, and a combination of somewhat less frequent regional trains making a few stops on the main line and many intercity trains making fewer stops. In contrast, the Ringbahn has no systemic express service: the S-Bahn includes trains running on the entire Ring frequently as well as trains running along segments of it stopping at every station on the way, but the only express services are regional trains that only serve small slivers on their way somewhere else and only come once or twice an hour.

This arrangement is mirrored in other cities. In Paris, the entire Metro network except Line 14 is very local, with the shortest interstations and lowest average speeds among major world metro systems. For faster service, there is Line 14 as well as the RER system, tying the suburbs together with the city. Those lines are exclusively radial. The busiest single RER line, the RER A, was from the start designed as an express line parallel to Line 1, the Metro’s busiest, and the second busiest, the RER B, is to a large extent an express version of the Metro’s second busiest line, Line 4. However, there is no RER version of the next busiest local lines, the ring formed by Lines 2 and 6. For non-Metro circumferential service, the region went down the speed/cost tradeoff and built tramways, which have been a total success and have high ridership even though they’re slow.

In New York, the subway was built with four-track main lines from the start to enable express service. Five four-track lines run north-south in Manhattan, providing local and express service. Outside the Manhattan core, they branch and recombine into a number of three- and four-track lines in Brooklyn, Queens, and the Bronx. Not every radial line in New York has express service, but most do. In contrast, the circumferential Crosstown Line, carrying the G train, is entirely local.

In Seoul, most lines have no express service. However, Lines 1, 3, and 4 interline with longer-range commuter rail services, and Lines 1 and 4 have express trains on the commuter rail segments. They are all radial; the circumferential Line 2 has no express trains.

Finally, in London, the Underground has few express segments (all radial), but in addition to the Underground the city has or will soon have express commuter lines, including Thameslink and Crossrail. There are no plans for express service parallel to the Overground.

Is Tokyo really an exception?

Tokyo has express trains on many lines. On the JR East network, there are lines with four or six tracks all the way to Central Tokyo, with local and express service. The private railroads usually have local and express services on their own lines, which feed into the local Tokyo subway. But not all express services go through the primary city center: the Ikebukuro-Shibuya corridor has the four-track JR Yamanote Line, with both local services (called the Yamanote Line too, running as a ring to Tokyo Station) and express services (called the Saikyo or Shonan-Shinjuku Line, continuing north and south of the city); Tokyo Metro’s Fukutoshin Line, serving the same corridor, has a timed passing segment for express trains as well.

However, in three ways, the area around Ikebukuro, Shinjuku, and Shibuya behaves as a secondary city center rather than a circumferential corridor. The job density around all three stations is very high, for one. They have extensive retail as well, as the private railroads that terminated there before they interlined with the subway developed the areas to encourage more people to use their trains. This situation is also true of some secondary clusters elsewhere in Tokyo, like Tobu’s Asakusa terminal, but Asakusa is in a historically working-class area, whereas the Yamanote area was historically and still is wealthier, making it easier for it to attract corporate jobs.

Second, from the perspective of the transportation network, they are central enough that railroads that have the option to serve them do so, even at the expense of service to Central Tokyo. When the Fukutoshin Line opened, Tokyu shifted one of its two mainlines, the Toyoko Line, to connect to it and serve this secondary center, where it previously interlined with the Hibiya Line to Central Tokyo; Tokyu serves Central Tokyo via its other line, the Den-en-Toshi Line, which connects to the Hanzomon Line of the subway. JR East, too, prioritizes serving Shinjuku from the northern and southern suburbs: the Shonan-Shinjuku Line is a reverse-branch of core commuter rail lines both north and south, as direct fast service from the suburbs to Shibuya, Shinjuku, and Ikebukuro is important enough to JR East that it will sacrifice some reliability and capacity to Tokyo Station for it.

Third, as we will discuss below, the Yamanote Line has a special feature missing from circumferential corridors in Berlin and Paris: it has distinguished stations. A foreigner looking at satellite photos of land use and at a map of the region’s rail network without the stations labeled would have an easy time deciding where an express train on the line should stop: Ikebukuro, Shinjuku, and Shibuya eclipse other stations along the line, like Yoyogi and Takadanobaba. Moreover, since these three centers were established to some extent before the subway was built, the subway lines were routed to serve them; there are 11 subway lines coming from the east as well as the east-west Chuo Line, and of these, all but the Tozai and Chiyoda Lines intersect it at one of the three main stations.

Interstations and trip length

The optimal stop spacing depends on how long passenger trips are on the line: keeping all else equal, it is proportional to the square root of the average unlinked trip. The best formula is somewhat more delicate: widening the stop spacing encourages people to take longer trips as they become faster with fewer intermediate stops and discourages people from taking shorter ones as they become slower with longer walk distances to the station. However, to a first-order approximation, the square root rule remains valid.

The relevance is that not all lines have the same average trip length. Longer lines have longer trips than short lines. Moreover, circular lines have shorter average trips than straight lines of the same length, because people have no reason to ride the entire way. The Ringbahn is a 37-kilometer line on which trains take an hour to complete the circuit. But nobody has a reason to ride more than half the circle – they can just as well ride the shorter way in the other direction. Nor do passengers really have a reason to ride over exactly half the circle, because they can often take the Stadtbahn, North-South Tunnel, or U-Bahn and be at their destinations faster.

Circumferential lines are frequently used to connect to radial lines if the radial-radial connection in city center is inconvenient – maybe it’s missing entirely, maybe it’s congested, maybe it involves too much walking between platforms, maybe happens to be on the far side of city center. In all such cases, people are more likely to use the circumferential line for shorter trips than for longer ones: the more acute the angle, the more direct and thus more valuable the circle is for travel.

The relevance of this discussion to express service is that there’s more demand for express service in situations with longer optimum stop spacing. For example, the optimum stop spacing for the subway in New York based on current travel patterns is the same as that proposed for Second Avenue Subway, to within measurement error of parameters like walking speed; on the other trunk lines, the local trains have denser stop spacing and the express trains have wider stop spacing. On a line with very short optimum spacing, there is not much of a case for express service at all.

Distinguished stops versus isotropy

The formula for optimal stop spacing depends on the isotropy of travel demand. If origins and destinations are distributed uniformly along the line, then the optimal stop spacing is minimized: passengers are equally likely to live and work right on top of a station, which eliminates walk time, as they are to live and work exactly in the middle between two stations, which maximizes walk time. If the densities of origins and destinations are spiky around distinguished nodes, then the optimal stop spacing widens, because planners can place stations at key locations to minimize the number of passengers who have to walk longer. If origins are assumed to be perfectly isotropic but destinations are assumed to be perfectly clustered at such distinguished locations as city center, the optimum stop spacing is larger than if both are perfectly isotropic by a factor of \sqrt{2}.

Circumferential lines in large cities do not have isotropic demand. However, they have a great many distinguished stops, one at every intersection with a radial rail service. Out of 27 Ringbahn stops, 21 have a connection to the U-Bahn, a tramway, or a radial S-Bahn line. Express service would be pointless – the money would be better spent increasing local frequency, as ridership on short-hop trips like the Ringbahn’s is especially sensitive to wait time.

On the M2/M6 ring in Paris, there are 49 stops, of which 21 have connections to other Metro lines or the RER, one more doesn’t but really should (Rome, with a missed connection to an M14 extension), and one may connect to a future extension of M10. Express service is not completely pointless parallel to M2/M6, but still not too valuable. Even farther out, where the Paris region is building the M15 ring of Grand Paris Express, there are 35 stops in 69 kilometers of the main ring, practically all connecting to a radial line or located at a dense suburban city center.

The situation in New York is dicier, because the G train does have a distinguished stop location between Long Island City and Downtown Brooklyn, namely the connection to the L train at Bedford Avenue. However, the average trip length remains very short – the G misses so many transfers at both ends that end-to-end riders mostly stay on the radials and go through Manhattan, so the main use case is taking it a few stops to the connection to the L or to the Long Island City end.

Conclusion

A large urban rail network should be predominantly radial, with circumferential lines in dense areas providing additional connectivity between inner neighborhoods and decongesting the central transfer points. However, that the radial and circumferential lines are depicted together on the same metro or regional rail map does not mean that people use them in the same way. City center lies ideally on all radials but not on the circumferentials, so the tidal wave of morning commuters going from far away to the center is relevant only to the radials.

This difference between radials and circumferentials is not just about service planning, but also about infrastructure planning. Passengers make longer trips on radial lines, and disproportionately travel to one of not many distinguished central locations; this encourages longer stop spacing, which may include express service in the largest cities. On circumferential lines, they make shorter trips to one of many different connection points; this encourages shorter stop spacing and no express service, but rather higher local frequency whenever possible.

Different countries build rapid transit in radically different ways, and yet big cities in a number of different countries have converged on the same pattern: express service on the strongest radial corridors, local-only service on circumferential ones no matter how busy they are. There is a reason. Transportation planners in poorer cities that are just starting to build their rapid transit networks as well in mature cities that are adding to their existing service should take heed and design infrastructure accordingly.

S-Bahn and RegionalBahn

The American rail activist term regional rail refers to any mainline rail service short of intercity, which lumps two distinct service patterns. In some German cities, these patterns are called S-Bahn and RegionalBahn, with S-Bahn referring to urban rail running on mainline tracks and RegionalBahn to longer-range service in the 50-100 km range and sometimes even beyond. It’s useful to distinguish the two whenever a city wishes to invest in its regional rail network, because the key infrastructure for the two patterns is different.

As with many this-or-that posts of mine, the distinction is not always clear in practice. For one, in smaller cities, systems that are labeled S-Bahns often work more like RegionalBahn, for example in Hanover. Moreover, some systems have hybrid features, like the Zurich S-Bahn – and what I’ve advocated in American contexts is a hybrid as well. That said, it’s worth understanding the two different ends of this spectrum to figure out what the priority for rail service should be in each given city.

S-Bahn as urban rail

The key feature of the S-Bahn (or the Paris RER) is that it has a trunk that acts like a conventional urban rapid transit line. There are 6-14 stations on the trunks in the examples to keep in mind, often spaced toward the high end for rapid transit so as to provide express service through city center, and all trains make all stops, running every 3-5 minutes all day. Even if the individual branches run on a clockface schedule, people do not use the trunk as a scheduled railroad but rather show up and go continuously.

Moreover, the network layout is usually complementary with existing urban rail. The Munich S-Bahn was built simultaneously with the U-Bahn, and there is only one missed connection between them, The Berlin S-Bahn and U-Bahn were built separately as patchworks, but they too have one true missed connection and one possible miss that depends on which side of the station one considers the crossing point to be on. The RER has more missed connections with the Metro, especially on the RER B, but the RER A’s station choice was designed to maximize connections to the most important lines while maintaining the desired express stop spacing.

Urban rail lines rarely terminate at city center, and the same is true for S-Bahn lines. In cities whose rail stations are terminals, such as Paris, Munich, Frankfurt, and Stuttgart, there are dedicated tunnels for through-service; London is building such a tunnel in Crossrail, and built one for Thameslink, which has the characteristics of a hybrid. In Japan, too, the first priority for through-running is the most local S-Bahn-like lines – when there were only six tracks between Tokyo and Ueno, the Yamanote and Keihin-Tohoku Lines ran through, as did the Shinkansen, whereas the longer-range regional lines terminated at the two ends until the recent through-line opened.

The difference between an S-Bahn and a subway is merely that the subway is self-contained, whereas the S-Bahn connects to suburban branches. In Tokyo even this distinction is blurred, as most subway lines connect to commuter rail lines at their ends, often branching out.

RegionalBahn as intercity rail

Many regional lines descend from intercity lines that retooled to serve local traffic. Nearly every trunk line entering London from the north was built as a long-range intercity line, most commuter rail mainlines in New York are inner segments of lines that go to other cities or used to (even the LIRR was originally built to go to Boston, with a ferry connection), and so on.

In Germany, it’s quite common for such lines to maintain an intercity characteristic. The metropolitan layout of Germany is different from that of the English-speaking world or France. Single-core metro regions are rather small, except for Berlin. Instead, there are networks of independent metropolitan cores, of which the largest, the Rhine-Ruhr, forms an urban complex almost as large as the built-up areas of Paris and London. Even nominally single-core metro regions often have significant independent centers with long separate histories. I blogged about the Rhine-Neckar six months ago as one such example; Frankfurt is another, as the city is ringed by old cities including Darmstadt and Mainz.

But this is not a purely German situation. Caltrain connects what used to be two independent urban areas in San Francisco and San Jose, and many outer ends of Northeastern American commuter lines are sizable cities, such as New Haven, Trenton, Providence, and Worcester.

The intercity characteristic of such lines means that there is less need to make them into useful urban rail; going express within the city is more justifiable if people are traveling from 100 km away, and through-running is a lower priority. Frequency can be lower as well, since the impact of frequency is less if the in-vehicle travel time is longer; an hourly or half-hourly takt can work.

S-Bahn and RegionalBahn combinations

The S-Bahn and RegionalBahn concepts are distinct in history and service plan, but they do not have to be distinct in branding. In Paris, the distinction between Transilien and the RER is about whether there is through-running, and thus some lines that are RegionalBahn-like are branded as RER, for example the entire RER C. Moreover, with future extension plans, the RER brand will eventually take over increasingly long-distance regional service, for example going east to Meaux. Building additional tunnels to relieve the worst bottlenecks in the city’s transport network could open the door to connecting every Transilien line to the RER.

Zurich maintains separate brands for the S-Bahn and longer-distance regional trains, but as in Paris, the distinction is largely about whether trains terminate on the surface or run through either of the tunnels underneath Hauptbahnhof. Individual S-Bahn branches run every half hour, making extensive use of interlining to provide high frequency to urban stations like Oerlikon, and many of these branches go quite far out of the city. It’s not the same as the RER A and B or most of the Berlin S-Bahn, with their 10- and 15-minute branch frequencies and focus on the city and innermost suburbs.

But perhaps the best example of a regional rail network that really takes on lines of both types is that of Tokyo. In branding, the JR East network is considered a single Kanto-area commuter rail network, without distinctions between shorter- and longer-range lines. And yet, the rapid transit services running on the Yamanote, Keihin-Tohoku, and Chuo-Sobu Lines are not the same as the highly-branched network of faster, longer-range lines like Chuo Rapid, Yokosuka, Sobu Rapid, and so on.

The upshot is that cities do not need to neatly separate their commuter rail networks into two separate brands as Berlin does. The distinction is not one of branding for passengers, but one of planning: should a specific piece of infrastructure be S-Bahn or RegionalBahn?

Highest and best use for infrastructure

Ordinarily, the two sides of the spectrum – an S-Bahn stopping every kilometer within the city, and a RegionalBahn connecting Berlin with Magdeburg or New York with New Haven – are so different that there’s no real tradeoff between them, just as there is no tradeoff between building subways and light rail in a city and building intercity rail. However, they have one key characteristic leading to conflict: they run on mainline track. This means that transportation planners have to decide whether to use existing mainline tracks for S-Bahn or RegionalBahn service.

Using different language, I talked about this dilemma in Boston’s context in 2012. The situation of Boston is instructive even in other cities, even outside the United States, purely because its commuter rail service is so bad that it can almost be viewed as blank slate service on existing infrastructure. On each of the different lines in Boston, it’s worth asking what the highest and best use for the line is. This really boils down to two questions:

  1. Would the line fill a service need for intra-urban travel?
  2. Does the line connect to important outlying destinations for which high speed would be especially beneficial?

In Boston, the answer to question 1 is for the most part no. Thirty to forty years ago the answer would have been yes for a number of lines, but since then the state has built subway lines in the same rights-of-way, ignorant of the development of the S-Bahn concept across the Pond. The biggest exceptions are the Fairmount Line through Dorchester and the inner Fitchburg Line through suburbs of Cambridge toward Brandeis.

On the Fairmount Line the answer to question 2 is negative as well, as the line terminates within Boston, which helps explain why the state is trying to invest in making it a useful S-Bahn with more stops, just without electrification, high frequency, fare integration, or through-service north of Downtown Boston. But on the Fitchburg Line the answer to question 2 is positive, as there is quite a lot of demand from suburbs farther northwest and a decent anchor in Fitchburg itself.

The opposite situation to that of Fairmount is that of the Providence Line. Downtown Providence is the largest job center served by the MBTA outside Boston; the city ranks third in New England in number of jobs, behind Boston and Cambridge and ahead of Worcester and Hartford. Fast service between Providence and Boston is obligatory. However, Providence benefits from lying on the Northeast Corridor, which can provide such service if the regional trains are somewhat slower; this is the main justification for adding a handful of infill stops on the Providence Line.

In New York, the situation is the most complicated, befitting the city’s large size and constrained location. On most lines, the answers to both questions is yes: there is an urban rail service need, either because there is no subway service (as in New Jersey) or because there is subway service and it’s overcrowded (as on the 4/5 trains paralleling the Metro-North trunk and on the Queens Boulevard trains paralleling the LIRR trunk); but at the same time, there are key stations located quite far from the dense city, which can be either suburban centers 40 km out or, in the case of New Haven, an independent city more than 100 km out.

Normally, in a situation like New York’s, the solution should be to interline the local lines and keep the express lines at surface terminals; London is implementing this approach line by line with the Crossrail concept. Unfortunately, New York’s surface terminals are all outside Manhattan, with the exception of Grand Central. Penn Station has the infrastructure for through-running because already in the 1880s and 90s, the ferry transfers out of New Jersey and Brooklyn were onerous, so the Pennsylvania Railroad invested in building a Manhattan station fed by east-west tunnels.

I call for complete through-running in New York, sometimes with the exception of East Side Access, because of the island geography, which makes terminating at the equivalent of Gare du Nord or Gare de Lyon too inconvenient. In other cities, I might come to different conclusions – for example, I don’t think through-running intercity trains in Chicago is a priority. But in New York, this is the only way to guarantee good regional rail service; anything else would involve short- and long-range trains getting in each other’s way at Penn Station.

Deutschlandtakt and Country Size

Does the absolute size of a country matter for public transport planning? Usually it does not – construction costs do not seem to be sensitive to absolute size, and the basics of rail planning do not either. That Europe’s most intensely used mainline rail networks are those of Switzerland and the Netherlands, two geographically small countries, is not really about the inherent benefits of small size, but about the fact that most countries in Europe are small, so we should expect the very best as well as the very worst to be small.

But now Germany is copying Swiss and Dutch ideas of nationally integrated rail planning, in a way that showcases where size does matter. For decades Switzerland has had a national clockface schedule in which all trains are coordinated for maximum convenience of interchange between trains at key stations. For example, at Zurich, trains regularly arrive just before :00 and :30 every hour and leave just after, so passengers can connect with minimum wait. Germany is planning to implement the same scheme by 2030 but on a much bigger scale, dubbed Deutschlandtakt. This plan is for the most part good, but has some serious problems that come from overlearning from small countries rather than from similar-size France.

In accordance with best industry practices, there is integration of infrastructure and timetable planning. I encourage readers to go to the Ministry of Transport (BMVI) and look at some line maps – there are links to line maps by region as well as a national map for intercity trains. The intercity train map is especially instructive when it comes to scale-variance: it features multihour trips that would be a lot shorter if Germany made a serious attempt to build high-speed rail like France.

Before I go on and give details, I want to make a caveat: Germany is not the United States. BMVI makes a lot of errors in planning and Deutsche Bahn is plagued by delays; these are still basically professional organizations, unlike the American amateur hour of federal and state transportation departments, Amtrak, and sundry officials who are not even aware Germany has regional trains. As in London and Paris, the decisions here are defensible, just often incorrect.

Run as fast as necessary

Switzerland has no high-speed rail. It plans rail infrastructure using the maxim, run trains as fast as necessary, not as fast as possible. Zurich, Basel, and Bern are around 100 km from one another by rail, so the federal government invested in speeding up the trains so as to serve each city pair in just less than an hour. At the time of this writing, Zurich-Bern is 56 minutes one-way and the other two pairs are 53 each. Trains run twice an hour, leaving each of these three cities a little after :00 and :30 and and arriving a little before, enabling passengers to connect to onward trains nationwide.

There is little benefit in speeding up Switzerland’s domestic trains further. If SBB increases the average speed to 140 km/h, comparable to the fastest legacy lines in Sweden and Britain, it will be able to reduce trip times to about 42 minutes. Direct passengers would benefit from faster trips, but interchange passengers would simply trade 10 minutes on a moving train for 10 minutes waiting for a connection. Moreover, drivers would trade 10 minutes working on a moving train for 10 minutes of turnaround, and the equipment itself would simply idle 10 minutes longer as well, and thus there would not be any savings in operating costs. A speedup can only fit into the national takt schedule if trains connect each city pair in just less than half an hour, but that would require average speeds near the high end of European high-speed rail, which are only achieved with hundreds of kilometers of nonstop 300 km/h running.

Instead of investing in high-speed rail like France, Switzerland incrementally invests in various interregional and intercity rail connections in order to improve the national takt. To oversimplify a complex situation, if a city pair is connected in 1:10, Switzerland will invest in reducing it to 55 minutes, in order to allow trains to fit into the hourly takt. This may involve high average speeds, depending on the length of the link. Bern is farther from Zurich and Basel than Zurich and Basel are from each other, so in 1996-2004, SBB built a 200 km/h line between Bern and Olten; it has more than 200 trains per day of various speed classes, so in 2007 it became the first railroad in the world to be equipped with ETCS Level 2 signaling.

With this systemwide thinking, Switzerland has built Europe’s strongest rail network by passenger traffic density, punctuality, and mode share. It is this approach that Germany seeks to imitate. Thus, the Deutschlandtakt sets up control cities served by trains on a clockface schedule every 30 minutes or every hour. For example, Erfurt is to have four trains per hour, two arriving just before :30 and leaving just after and two arriving just before :00 and leaving just after; passengers can transfer in all directions, going north toward Berlin via either Leipzig or Halle, south toward Munich, or west toward Frankfurt.

Flight-level zero airlines

Richard Mlynarik likes to mock the idea of high-speed rail as conceived in California as a flight-level zero airline. The mockery is about a bunch of features that imitate airlines even when they are inappropriate for trains. The TGV network has many flight-level zero airline features: tickets are sold using an opaque yield management system; trains mostly run nonstop between cities, so for example Paris-Marseille trains do not stop at Lyon and Paris-Lyon trains do not continue to Marseille; frequency is haphazard; transfers to regional trains are sporadic, and occasionally (as at Nice) TGVs are timed to just miss regional connections.

And yet, with all of these bad features, SNCF has higher long-distance ridership than DB, because at the end of the day the TGVs connect most major French cities to Paris at an average speed in the 200-250 km/h range, whereas the fastest German intercity trains average about 170 and most are in the 120-150 range. The ICE network in Germany is not conceived as complete lines between pairs of cities, but rather as a series of bypasses around bottlenecks or slow sections, some with a maximum speed of 250 and some with a maximum speed of 300. For example, between Berlin and Munich, only the segments between Ingolstadt and Nuremberg and between Halle and north of Bamberg are on new 300 km/h lines, and the rest are on upgraded legacy track.

Even though the maximum speed on some connections in Germany is the same as in France, there are long slow segments on urban approaches, even in cities with ample space for bypass tracks, like Berlin. The LGV Sud-Est diverges from the classical line 9 kilometers outside Paris and permits 270 km/h 20 kilometers out; on its way between Paris and Lyon, the TGV spends practically the entire way running at 270-300 km/h. No high-speed lines get this close to Berlin or Munich, even though in both cities, the built-up urban area gives way to farms within 15-20 kilometers of the train station.

The importance of absolute size

Switzerland and the Netherlands make do with very little high-speed rail. Large-scale speedups are of limited use in both countries, Switzerland because of the difficulty of getting Zurich-Basel trip times below half an hour and the Netherlands because all of its major cities are within regional rail distance of one another.

But Germany is much bigger. Today, ICE trains go between Berlin and Munich, a distance of about 600 kilometers, in just less than four hours. The Deutschlandtakt plan calls for a few minutes’ speedup to 3:49. At TGV speed, trains would run about an hour faster, which would fit well with timed transfers at both ends. Erfurt is somewhat to the north of the midpoint, but could still keep a timed transfer between trains to Munich, Frankfurt, and Berlin if everything were sped up.

Elsewhere, DB is currently investing in improving the line between Stuttgart and Munich. Trains today run on curvy track, taking about 2:13 to do 250 km. There are plans to build 250 km/h high-speed rail for part of the way, targeting a trip time of 1:30; the Deutschlandtakt map is somewhat less ambitious, calling for 1:36, with much of the speedup coming from Stuttgart21 making the intercity approach to Stuttgart much easier. But with a straight line distance of 200 km, even passing via Ulm and Augsburg, trains could do this trip in less than an hour at TGV speeds, which would fit well into a national takt as well. No timed transfers are planned at Augsburg or Ulm. The Baden-Württemberg map even shows regional trains (in blue) at Ulm timed to just miss the intercity trains to Munich. Likewise, the Bavaria map shows regional trains at Augsburg timed to just miss the intercity trains to Stuttgart.

The same principle applies elsewhere in Germany. The Deutschlandtakt tightly fits trains between Munich and Frankfurt, doing the trip in 2:43 via Stuttgart or 2:46 via Nuremberg. But getting Munich-Stuttgart to just under an hour, together with Stuttgart21 and a planned bypass of the congested Frankfurt-Mannheim mainline, would get Munich-Frankfurt to around two hours flat. Via Nuremberg, a new line to Frankfurt could connect Munich and Frankfurt in about an hour and a half at TGV speed; even allowing for some loose scheduling and extra stops like Würzburg, it can be done in 1:46 instead of 2:46, which fits into the same integrated plan at the two ends.

The value of a tightly integrated schedule is at its highest on regional rail networks, on which trains run hourly or half-hourly and have one-way trip times of half an hour to two hours. On metro networks the value is much lower, partly because passengers can make untimed transfers if trains come every five minutes, and partly because when the trains come every five minutes and a one-way trip takes 40 minutes, there are so many trains circulating at once that the run-as-fast-as-necessary principle makes the difference between 17 and 18 trainsets rather than that between two and three. In a large country in which trains run hourly or half-hourly and take several hours to connect major cities, timed transfers remain valuable, but running as fast as necessary is less useful than in Switzerland.

The way forward for Germany

Germany needs to synthesize the two different rail paradigms of its neighbors – the integrated timetables of Switzerland and the Netherlands, and the high-speed rail network of France.

High investment levels in rail transport are of particular importance in Germany. For too long, planning in Germany has assumed the country would be demographically stagnant, even declining. There is less justification for investment in infrastructure in a country with the population growth rate of Italy or of last decade’s Germany than in one with the population growth rate of France, let alone one with that of Australia or Canada. However, the combination of refugee resettlement and a very strong economy attracting European and non-European work migration is changing this calculation. Even as the Ruhr and the former East Germany depopulate, we see strong population growth in the rich cities of the south and southwest as well as in Berlin.

The increased concentration of German population in the big cities also tilts the best planning in favor of the metropolitan-centric paradigm of France. Fast trains between Berlin, Frankfurt, and Munich gain value if these three cities grow in population whereas the smaller towns between them that the trains would bypass do not.

The Deutschlandtakt’s fundamental idea of a national integrated timed transfer schedule is good. However, a country the size and complexity of Germany needs to go beyond imitating what works in Switzerland and the Netherlands, and innovate in adapting best practices for its particular situation. People keep flying domestically since the trains take too long, or they take buses if the trains are too expensive and not much faster. Domestic flights are not a real factor in the Netherlands, and barely at all in Switzerland; in Germany they are, so trains must compete with them as well as with flexible but slow cars.

The fact that Germany already has a functional passenger rail network argues in favor of more aggressive investment in high-speed rail. The United States should probably do more than just copy Switzerland, but with nonexistent intercity rail outside the Northeast Corridor and planners who barely know that Switzerland has trains, it should imitate rather than innovating. Germany has professional planners who know exactly how Germany falls short of its neighbors, and will be leaving too many benefits on the table if it decides that an average speed of about 150 km/h is good enough.

Germany can and should demand more: BMVI should enact a program with a budget in the tens of billions of euros to develop high-speed rail averaging 200-250 km/h connecting all of its major cities, and redo the Deutschlandtakt plans in support of such a network. Wedding French success in high-speed rail and Swiss and Dutch success in systemwide rail integration requires some innovative planning, but Germany is capable of it and should lead in infrastructure construction.

Little Things That Matter: Interchange Siting

I’ve written a lot about the importance of radial network design for urban metros, for examples here, here, here, here, and here. In short, an urban rail network should look something like the following diagram:

That is, every two radial routes should intersect exactly once, with a transfer. In this post I am going to zoom in on a specific feature of importance: the location of the intersection points. In most cities, the intersection points should be as close as possible to the center, first in order to serve the most intensely developed location by all lines, and second in order to avoid backtracking.

The situation in Berlin

Here is the map of the central parts of Berlin’s U- and S-Bahn network, with my apartment in green and three places I frequently go to in red:

(Larger image can be found here.)

The Ring is severed this month due to construction: trains do not run between Ostkreuz, at its intersection with the Stadtbahn, and Frankfurter Allee, one stop to the north at the intersection with U5. As a result, going to the locations of the two northern red dots requires detours, namely walking longer from Warschauer Strasse to the central dot, and making a complex trip via U7, U8, and U2 to the northern dot.

But even when the Ring is operational, the Ring-to-U2 trip to the northern dot in Prenzlauer Berg is circuitous, and as a result I have not made it as often as I’d have liked; the restaurants in Prenzlauer Berg are much better than in Neukölln, but I can’t go there as often now. The real problem is not just that the Ring is interrupted due to construction, but that the U7-U2 connection is at the wrong place for the city’s current geography: it is too far west.

As with all of my criticism of Berlin’s U-Bahn network layout, there is a method to the madness: most of the route of U7 was built during the Cold War, and if you assumed that Berlin would be divided forever, the alignment would make sense. Today, it does not: U7 comes very close to U2 in Kreuzberg but then turns southwest to connect with the North-South Tunnel, which at the time was part of the Western S-Bahn network, running nonstop in the center underneath Mitte, then part of the East.

On hindsight, a better radial design for U7 would have made it a northwest-southeast line through the center. West of the U6 connection at Mehringdamm it would have connected to the North-South Tunnel at Anhalter Bahnhof and to U2 at Mendelssohn Park, and then continued west toward the Zoo. That area between U1/U2 and Tiergarten Park is densely developed, with its northern part containing the Cold War-era Kulturforum, and in the Cold War the commercial center of West Berlin was the Zoo, well to the east of the route of U7.

Avoiding three-seat rides

If the interchange points between lines are all within city center, then the optimal route between any two points is at worst a two-seat ride. This is important: transfers are pretty onerous, so transit planners should minimize them when it is reasonably practical. Two-seat rides are unavoidable, but three-seat rides aren’t.

The two-seat ride rule should be followed to the spirit, not the letter. If there are two existing lines with a somewhat awkward transfer, and a third line is built that makes a three-seat ride better than connecting between those two lines, then the third line is not by itself a problem, and it should be built if its projected ridership is sufficient. The problem is that the transfer was at the wrong location, or maybe at the right location but with too long a walk between the platforms.

Berlin’s awkward U-Bahn network is such that people say that the travel time between any two points within the Ring is about 30 minutes, no matter what. When I tried pushing back, citing a few 20-minute trips, my interlocutors noted that with walking time to the station, the inevitable wait times, and transfers, my 20-minute trips were exceptional, and most were about 30 or slightly longer.

The value of an untimed transfer rises with frequency. Berlin runs the U-Bahn every 5 minutes during the daytime on weekdays and the S-Bahn mostly every 5 minutes (or slightly better) as well; wait times are shorter in a city like Paris, where much of the Metro runs every 3 minutes off-peak, and only drops to 5 or 6 minutes late in the evening, when Berlin runs trains every 10 minutes. However, Parisian train frequencies are only supportable in huge cities like Paris, London, and Tokyo, all of which have very complex transfers, as the cities are so intensely built that the only good locations for train platforms require long walks between lines.

New York of course has the worst of all worlds: a highly non-radial subway network with dozens of missed connections, disappointing off-peak frequencies, and long transfer corridors in Midtown. In New York, three-seat rides are ubiquitous, which may contribute to weak off-peak ridership. Who wants to take three separate subway lines, each coming every 10 minutes, to go 10 kilometers between some residential Brooklyn neighborhood and a social event in Queens?