Category: Good Transit

Public Transportation in Megacities

I’ve been talking so much lately about integrated timed transfer in the context of Boston that people started asking me if it’s also applicable to New York. The answer is that the basic principles are not scale-dependent, but the implementation is, so in very large cities, public transport planning should not look like in Switzerland, a country whose largest metro area is staring at 2 million people from the bottom.

The one caveat here is that most cities are not huge. The developed world has seven megacities: Tokyo, Seoul, New York, Los Angeles, Osaka, London, Paris. And Los Angeles doesn’t really have public transportation, so we’re down to six. The middle-income world has a bunch more for sanity checking – Mexico City, São Paulo, Rio de Janeiro, Buenos Aires, Johannesburg, Moscow, Istanbul, Tehran, Beijing, Shanghai, Guangzhou, Shenzhen, Bangkok – but all are either still in convergence mode building up their networks or (mostly in Latin America) have given up. So much of this comes down to the idiosyncrasies of six cities, of which the largest three networks are substantially in the same planning tradition.

Demand is huge

Big cities have big centers, which can’t really be served by any mode except rapid transit. Even in Los Angeles, what passes for a central business district has around a 50% public transport modal split. This means that the transport network has to deliver high throughput to a relatively small city center. Even in a low-kurtosis city like Paris, most Métro lines converge on a narrow area ranging from Les Halles to Saint-Lazare; in a high-kurtosis one like New York or Tokyo, there are a few square kilometers with 200,000 jobs per km^2, which require an exceptionally dense network of rapid transit lines.

Some other network design principles follow from the need to amply serve city center. Specifically, high frequency is rarely a worry, because there’s so much demand even off-peak that usually megacity subway systems do not venture into the frequency range where long waits deter traffic; New York’s 10-minute midday gaps are bad, but that’s unusual and it comes from a combination of the legacy of postwar fear of subway crime suppressing demand and excessive branching.

But other principles require careful planning still.

Electronics before concrete, megacity version

The driverless lines in Paris support peak throughput of 42 trains per hour – a train every 85 seconds. CBTC on Line 13 without driverless operation supports 38 tph, and London’s CBTC-equipped lines support 36 tph when the branching isn’t too complex. It is imperative for other cities to learn from this and do whatever they can to reach similar headways. The difference between 21 tph, as in Shanghai, and Paris’s 42, is equivalent to building a brand new subway line. And what’s more, in a city in the size class we’re talking about, the primary concern is capacity – coverage is already good, so there really is no reason to build two 21 tph lines instead of one 42 tph one.

The situation in Paris is in a context with self-contained lines. That said, extremely busy self-contained lines do exist in other megacities – London has a bunch with near-Parisian levels of throughput, New York has some, Tokyo has a few, Seoul and Osaka are both more self-contained than Tokyo is.

Throughput and organization

The primacy of throughput means that it’s worthwhile to build small infrastructure upgrades, even with concrete, if they help with capacity. Right now the Northern line reverse-branches with the branches to the north recombining with those in the center, and Transport for London would like to split the line in two, reducing branching complexity, which would increase capacity. But doing so requires improving pedestrian circulation in the corridors of the branch point, Camden Town, where TfL expects very large transfer volumes if there’s a split and already there are circulation problems today without a split. Hence the plan in the medium term is to upgrade Camden Town and then split.

If there are bumper tracks at the end of a line, as at 8th Avenue on the L or Flushing-Main Street on the 7, then it’s useful to dig up the street for another block just to add some tail tracks. That way, trains could enter the station at full speed. This increases throughput, because the terminal interlocking has trains heading in opposite directions crossing each other at-grade, which imposes schedule constraints; it’s best if trains can go through the interlocking as fast as possible to reduce the time they’re in a constrained environment, but that in turn requires short tail tracks so that an overrun of a few meters is not catastrophic. Ideally the tail tracks should even extend a full train length past the platform to place the interlocking on the other side of it, as is done in Paris and Moscow; in that case, trains cross the interlocking out of service, when it’s easier to control their exact timings.

Such projects are disruptive, but the disruption is very localized, to just one transfer station for a deinterlining project as in London or one terminal as in New York, and the impact on capacity is very large, if not quite as large as the full suite of signaling and track upgrades that make the difference between a train every 3 minutes and a train every 1.5 minutes.

Network design

The ideal metro network is radial. Megacities already support that just because so many lines have to serve city center. However, it’s important to make sure every pair of lines intersects, with a transfer. No large metro network in the world achieves this ideal – Mexico City’s network is the largest without missed connections, but it is not radial and its only three radial lines are overburdened while the other lines have light ridership. Paris has just a single missed connection on the Métro proper, not counting the RER, but it has many pairs of lines that do not intersect at all, such as M1 and M3. London is more or less a pure radial, but there are a handful of misses, including one without any transfer between the two lines anywhere, namely the Metropolian line (including Hammersmith and City) and the Charing Cross branch of the Northern line.

Big cities that plan out a metro network have to make sure they do better. Missed connections reduce passenger ridership and lead riders to overload the lines that do get connections; for example, in Tokyo one reason cited for the high ridership of the Tozai Line is that until Fukutoshin opened it was the only one with a transfer to every other subway line, and in Shanghai, Line 1 was extremely congested as long as the alternatives going north either had critical missed connections (like Line 8) or avoided city center (like Line 3).

The role of regional rail

Regional rail as a basic concept is mostly scale-invariant. However, the design principles for trains that come every half hour are not the same as those for trains that come every 5 minutes. If trains come every half hour, they had better connect cities in a roundtrip time equal to an integer number of half hours minus turnaround times, so that they don’t have to loiter 25 minutes at a terminal collecting dust and depreciating. If they come every 5 minutes, they’re not going to loiter 25 minutes anyway, and the difference between a 5-minute turnaround and a 7-minute turnaround is not really relevant.

The design principles are then mostly about throughput, again. The most important thing is to build independent trunk lines for trains to serve city center. Even in a huge city, the finances of building a purely greenfield subway deep into suburbia are poor; Tokyo has done it with the Tsukuba Express but it’s mostly above-ground, and for the most part regional lines there and elsewhere come from taking existing suburban lines and linking them with city center tunnels.

Tokyo’s insistence on making these city center tunnels also form a coherent metro network is important. Only one non-Tokyo example is worth mentioning to add to all of this: this is Berlin, which is not a megacity but has three independent S-Bahn trunk lines. Berlin, unlike London and Paris, painstakingly made sure the S-Bahn lines would have transfers with the U-Bahn; its network has only one U-Bahn/S-Bahn missed connection, which is better than the situation in Tokyo, Paris, or (with Thameslink and Crossrail) London.

The role of development

All first-world megacities, and I believe also all megacities elsewhere, have high housing demand by domestic standards. All are very wealthy by domestic standards except Los Angeles, and Los Angeles is still incredibly expensive, it just doesn’t have the high wages to compensate that London and New York and Paris have. In such an environment, there’s no need to try to be clever with steering development to transit-oriented sites. Anywhere development is legal, developers will build, and the public transport system has a role to play in opening more land for more intense development through fast trips to the center.

A laissez-faire approach to zoning is useful in such an environment. This contrasts with smaller cities’ reliance on finger plans, like the original one in Copenhagen or the growing one in and around Berlin. No limits on development anywhere are required. The state’s planning role remains strong through transportation planning, and the suburbs may well form natural finger plans if developers are permitted to replace single-family houses with apartment buildings anywhere, since the highest-value land is near train stations. But state planning of where housing goes is counterproductive – high transit ridership comes from the impossibility of serving a large central business district by cars, and the risk of politicization and policy capture by homeowners is too great.

The advantage of this approach is also that because in a high-demand city public transport can to some extent shape and not just serve development, it’s okay to build lines that are good from the perspective of network coherence, even if the areas they serve are a bit light. This principle does not extend indefinitely – subway and regional rail lines should still go where people are – but for example building key transfer points in near-center neighborhoods that are not in high demand is fine, because demand will follow, as is building lines whose main purpose is to close some gap in the network.

Construction costs

The larger the city, the more important cost control is. This may sound counterintuitive, since larger cities have more demand – only in Manhattan could a $1.7 billion/km extension like Second Avenue Subway pencil out – but larger cities also have a bigger risk of cost blowouts. Already Tokyo has stopped building new rapid transit in the core despite very high crowding levels on the existing network, and London builds next to nothing as well. New York’s poor cost control led Philip Plotch to entitle his book about Second Avenue Subway The Last Subway. Even Paris builds mostly in the suburbs. Extensive city center and near-center construction continues in Seoul, in the context of very low construction costs.

The flip side is that a New York (or even London) that can build subways at the cost of Paris, let alone Seoul, is one that can rapidly solve all of its transport problems. My Assume Nordic Costs map fixates on a region of the world with small cities, but the construction costs in South Korea are if anything lower than in the Nordic countries. And even that map, given free reins for developers, is underbuilt – some lines would look ridiculous at current costs and zoning but reasonable given low costs and liberal zoning, for example something meandering through currently industrial parts of New Jersey.

Small cities designed their public transportation philosophy around scarcity: Switzerland really can’t just draw crayon and build it, because housing and transport demand there are finite and limited. Cities like New York and London, in contrast, should think in terms of abundance of infrastructure and housing, provided their regulations are set up in a way that permits the state to build infrastructure at low costs and private homebuilders to redevelop large swaths as they become easily accessible to city center.

Integrated Timed Transfer Schedules for Buses

I’ve written a bunch about integrated timed transfer (ITT) scheduling based on Swiss and Dutch principles, developed for intercity and regional trains. Here, for example, is how this schema would work for trains connecting Boston and Worcester. But I’ve also seen interest in how buses can connect to one another, so I feel it’s useful to try to adapt the ITT to this different mode. Two particular places where I’ve seen this interest are a statewide plan for intercity buses in West Virginia, and regional integration around Springfield and the Five Colleges; I’m not going to make specific recommendation for either place, since I don’t know them nearly well enough, but I hope what I write will be helpful there and elsewhere.

The ITT principles for trains

ITT for trains relies on total coordination of all aspects of planning. The centerpiece of this is the triangle of infrastructure, rolling stock, and timetable, all of which must be planned together. Decisions on infrastructure spending should be based on what’s required to run the desired schedule, based on tight turnarounds, maximal utilization rates of equipment, and timed connections.

The even broader principle is to trade state complexity for money. It’s harder to plan everything together – different departments need to talk to one another, planning has to be lean or else the back-and-forth will take too long, regulations may have to be adjusted, government at all levels has to push in the same direction. The reason to do this chore is that it’s far cheaper than the alternative. Organization is cheaper than electronics and concrete at all levels; American households spend around 20% of their income on transportation, mostly cars, whereas households in transit cities like Paris or Berlin or Tokyo spend a fraction of that, even taking into account residual car ownership and operating subsidies to public transit.

On buses, there’s no such thing as electronics…

The Swiss maxim, electronics before concrete, concerns trains exclusively. On buses, no such thing exists. It’s not really possible to get higher-performance buses to make a more aggressive schedule. Acceleration rates depend on passenger safety and comfort and not on the motors (in fact, they’re higher on buses than on trains – rubber tires grip the road better than steel wheels grip rails). The closest analog is that electric buses are lower-maintenance, since the diesel engine is the most failure-prone part on buses as well as trains, but what this leads to, IMC, is not really a strategy for improving timetabling – IMC’s main benefits are less pollution and lower maintenance costs.

…but there is a surplus of organization to be done

All the little things that on trains go in the electronics bucket go in the organization bucket on buses. These include the following operating treatments to improve local bus speeds:

  • Off-board fare collection
  • Stop consolidation to one every 400-500 meters
  • Dedicated lanes in congested areas
  • Signal priority at busy intersections

In addition, bus shelter does not increase actual speed but does increase perceived speed, and should be included in every bus redesign in an area that lacks it.

These are all present in Eric’s and my Brooklyn bus redesign proposal, but that doesn’t make that proposal an ITT plan – for one, it’s based on 6-minute frequencies and untimed transfers, whereas ITT is based on half-hour frequencies (for the most part) and timed transfers. Of note, in a 6-minute context signal priority should be conditional to prevent bunching, but if buses run on a 30-minute or even 15-minute timetable then bunching is less likely, especially if buses have prepayment and some dedicated lanes.

That said, it’s important to talk about all of the above in this context, because a bus ITT belongs in areas where public transport ridership is so low that people view a bus every 15 minutes as an aspirational schedule. In such areas, the politics of giving buses more priority over cars are harder than in a city with low car usage like Paris or New York or Barcelona. There are some positive examples, like Rhode Island’s eventual passage of a bill giving six key bus corridors signal priority, but in Tampa I was told that DOT wouldn’t even let the bus agency bump up frequency unless it found money for repaving the street with concrete lanes.

What about intercity buses?

Prepayment, stop consolidation, and dedicated lanes are important for speeding up local buses. But intercity buses already stop sporadically, and often run on highways. There, speedup opportunities are more limited.

But there may still be some room for signal priority. If the bus only runs every hour or every half hour, then driver resistance may be reduced, since the vast majority of stoplight cycles at an intersection will not interact with a bus, and therefore the effect of the change on car speed will be small.

This is especially important if buses are to run on arterial roads and not on freeways. The significance is that highways are noisy, especially freeways, and do not have the concept of a station – freeways have exits but one takes an exit in a car, not on foot. Therefore, development does not cluster near a freeway, but rather wants to be a few minutes away from it, to avoid the noise and pollution. Arterials are better at this, though even then, it’s common for American big box stores and malls to be somewhat set away from those, requiring bus passengers to walk through parking lots and access roads.

Arterial roads, moreover, often do have stoplights, with punishing cycles optimized for auto throughput and not pedestrian-friendliness. In such cases, it’s crucial to give buses the highest priority: if these are intercity buses rather than coverage service to a suburb where nobody uses transit, they’re especially likely to be full of passengers, and then a bus with 40 passengers must receive 40 times the priority at intersections of a car with just a driver. Moreover, if it is at all possible to design stoplights so that passengers getting off the wrong side of the street, say on the east side for a northbound bus if the main development is west of the arterial, can cross the street safely.

Designing for reliability

The principles Eric and I used for the Brooklyn redesign, as I mentioned, are not ITT, because they assume frequency is so high nobody should ever look at a timetable. But the ITT concept goes in the exact opposite direction: it runs service every 15, 20, 30, or even 60 minutes, on a consistent clockface schedule (“takt”) all day, with arrival times at stations given to 1-minute precision.

Doing this on a bus network is not impossible, but is difficult. In Vancouver, the bus I would take to UBC, the 84, came on a 12-minute takt off-peak, and ranged between on time and 2 minutes late each cycle; I knew exactly when to show up at the station to make the bus. When I asked Jarrett Walker in 2017 why his American bus redesigns assume buses would run roughly every 15 minutes but not on such a precise schedule, he explained how American street networks, broken by freeways, have more variable traffic than Vancouver’s intact grid of many parallel east-west arterials.

So what can be done?

Dedicated lanes in congested areas are actually very useful here – if buses get their own lanes in town centers where traffic is the most variable, then they can make a consistent timetable, on top of just generally running faster. Signal priority has the same effect, especially on arterials as noted in the section above. Moreover, if the point is to make sure the noon timetable also works at 8:30 in the morning and 5:30 in the afternoon, then driver resistance is especially likely to be low. At 8:30 in the morning, drivers see a bus packed with passengers, and their ability to argue that nobody uses those bus lanes is more constrained.

New York as a Six-Minute City

What would it take to improve public transportation in New York so that all or nearly all routes would run at worst even six minutes during midday? Today, frequencies are tailored to individual routes; a bunch of subway lines are a 10-minute city (and the A branches are a 15-minute city), and in Brooklyn, the median midday bus headway is 12 minutes, with wide variations.

The bus origin of six minutes

Six minutes is not an arbitrary number. It comes from Eric’s and my Brooklyn bus redesign; speeding up routes through stop consolidation, dedicated lanes, and off-board fare collection, and pruning and recombining some routes, lets every bus run every six minutes from 6 am to 10 pm all day every day, with higher frequency on those routes that already have it today because they are too busy for just ten buses per hour. We didn’t study the other boroughs as deeply, but a quick doodle suggested the six-minute standard could be met in Manhattan and the Bronx as well, and a Bronx bus grid could even dip into a five-minute city.

Queens is a wildcard and I’m going to disappoint readers by not talking about it. It is clearly possible given the operational treatment we propose to make most of Queens a six-minute city, but at the price of long route spacing in Eastern Queens, and I don’t know what is optimal. It’s a hard question and I’m not going to tackle it unless I’m actually working on a longer-term project to do a Queens bus redesign.

Six minutes on the subway

The subway right now is a 10-minute city. A lettered or numbered route runs every 10 minutes off-peak, sometimes every 12 on Sundays and at night; the busier routes, especially the four that do not share tracks with other routes (1, 6, 7, L), run more frequently, but 10 minutes is the base frequency on large swaths of the network. The A branches in Ozone Park and the Rockaways even run every 15 minutes, but that’s unusual enough – evidently, nowhere else does one letter or number denote a route with its own branches – that it can be excluded.

For comparison, Berlin’s rail network is a 10-minute city, with some outer S-Bahn branches running every 20 minutes. Within the Ring, Berlin is a 5-minute city for the most part, excluding just a two-hour midday dip to 10 minutes on the Ring and 10-minute frequencies on the U1/U3 branches and the practically useless U4 route. Paris makes no effort to run different routes at the same intervals – French rapid transit planning has self-contained lines with their own fleets and schedules, so for example the RER A is on 10-minute off-peak takts and the RER B on 15-minute ones. So frequency there greatly depends on where in the region one lives and on what line. The Métro is a 5-minute city for the most part, as are the intramural RER trunks; intramural buses can be ignored. The suburbs are more or less a 15-minute city.

The reason New York is a 10-minute city on the subway is partly about interlining. The trunks in theory run every 5 minutes or better, but the trains do not come evenly because sometimes trains with different frequencies share the same trunk, and delays propagate easily. Interlining really doesn’t work unless all trains come at the same frequency; this is familiar in German planning, but not in American planning (or French planning, but there’s barely any interlining in Paris).

Putting every subway route on a 10-minute takt, with double service on the four non-interlined services, is possible but would lead to a lot of crowding on the busiest lines. About the worst possible frequency that works for everything is a train every 7.5 minutes; this lets the two A branches run on 15-minute takts, and everything else run on a 7.5-minute takt. But even then, New York has so many missed connections that it’s useful to do better. The six-minute city, matching buses, turns most of Manhattan and inner Brooklyn and Queens into a three-minute city.

Running all trains on the same takt also means timed connections. Trains that run every 5 or 6 minutes can routinely be timetabled to be at predictable places at predictable times, which facilitates local/express transfers on branches, for example in Southern Brooklyn. Even trunk transfers can be timed – 3-minute trains can still run on a timetable, and the most valuable transfers are local/express ones at 96th/Broadway, 125th/St. Nicholas, and 125th/Lex, all far enough north so as to not have the huge tidal crowds of Times Square or Grand Central.

What would it take?

On the buses, just good redesign, as long as the city is willing to exclude Staten Island from the six-minute city. In Queens, some increase in bus service is probably warranted.

On the subway, this requires on the order of 110-120 million revenue train-km a year, which is 1 billion car-km. The current figure is 560 million car-km/year. There is a lot of unnecessary expenditure on the subway, but fixing that requires something a lot deeper than a bus redesign. The cut in operating costs would be to levels that are well within first-world levels, and some of it would just come from better off-peak service making crew scheduling easier, without split shifts or wasted time. But it does require serious changes, especially in maintenance.

Quick Note: Timed Orbital Buses

Outside a city core with very high frequency of transit, say 8 minutes or better, bus and train services must be timetabled to meet each other with short connections as far as possible. Normally, this is done through setting up nodes at major suburban centers where trains and buses can all interchange. For example, see this post from six months ago about the TransitMatters proposal for trains between Boston and Worcester: on the hour every half hour, trains in both directions serve Framingham, which is the center for a small suburban bus system, and the buses should likewise run every half hour and meet with the trains in both directions.

This is a dendritic system, in which there is a clear hierarchy not just of buses and trains, but also of bus stops and train stations. Under the above system, every part of the Framingham area is connected by bus to the Framingham train station, and Framingham is then connected to the rest of Eastern New England via Downtown Boston. This is the easiest way to set up timed rail-bus connections: each individual rail line is planned around takt and symmetry such that the most important nodes can have easy timed bus connections, and then the buses are planned around the distinguished nodes.

However, there’s another way of doing this: a bus can connect two distinct nodes, on two different lines. The map I drew for a New England high- and low-speed rail has an orbital railroad doing this, connecting Providence, Worcester, and Fitchburg. Providence, as the second largest city center in New England, supplies such rail connections, including also a line going east toward Fall River and New Bedford, not depicted on the map as it requires extensive new construction in Downtown Providence, East Providence, and points east. But more commonly, a connection between two smaller nodes than Providence would be by bus.

The orbital bus is not easy to plan. It has to have timed connections at both ends, which imposes operational constraints on two distinct regional rail lines. To constrain planning even further, the bus itself has to work with its own takt – if it runs every half hour, it had better take an integer multiple of 15 minutes minus a short turnaround time to connect the two nodes.

It is also not common for two suburban stations on two distinct lines to lie on the same arterial road, at the correct distance from each other. For example, South Attleboro and Valley Falls are at a decent distance, if on the short side, but the route between them is circuitous and it would be far easier to try to set up a reverse-direction timed transfer at Central Falls for an all-rail route. The ideal distance for a 15-minute route is around 5-6 km; bus speeds in suburbia are fairly high when the buses run in straight lines, and if the density is so high that 5-6 km is too long for 15 minutes, then there’s probably enough density for much higher frequency than every half hour.

The upshot is that connections between two nodes are valuable, especially for people in the middle who then get easy service to two different rail lines, but uncommon. Brockton supplies a few, going west to Stoughton and east to Whitman and Abington. But the route to Stoughton is at 8.5 km a bit too long for 15 minutes – perhaps turning it into a 30-minute route, either with slightly longer connections or with a detour to Westgate (which the buses already take today), would be the most efficient. The routes to Whitman and Abington are 7 km long, which is feasible at the low density in between, but then timetabling the trains to set up knots at both Brockton and Abington/Whitman is not easy; Brockton is an easy node, but then since the Plymouth and Middleborough Lines are branches of the same system, their schedules are intertwined, and if Abington and Whitman are served 15 minutes away from Brockton then schedule constraints elsewhere lengthen turnaround times and require one additional trainset than if they are not nodes and buses can’t have timed connections at both ends.

Planners then have to keep looking for such orbital bus opportunities. There aren’t many, and there are many near-misses, but when they exist, they’re useful at creating an everywhere-to-everywhere network. It is even valuable to plan the trains accordingly provided other constraints are not violated, such as the above issue of the turnaround times on the Old Colony Lines.

Density and Subway Stop Spacing

Normally, the best interstation distance between subway or bus stops does not depend on population density. To resurrect past models, higher overall density means that there are more people near a potential transit stop, but also that there are more people on the train going through it, so overall it doesn’t influence the decision of whether the stop should be included or deleted. Relative density matters, i.e. there should be more stops in areas that along a line have higher density, for example city centers with high commercial density, but absolute density does not. However, there is one exception to the rule that absolute density does not matter, coming from line spacing and transfer placement. This can potentially help explain why Paris has such tight stop spacing on the Métro and why New York has such tight stop spacing on the local subway lines.

Stop spacing and line spacing

The spacing between transit stops interacts with that between transit lines. The reason is that public transportation works as a combined network, which requires every intersection between two lines to have a transfer. This isn’t always achieved in practice, though Paris has just one missed connection on the Métro (not the RER), M5/M14 near Bastille; New York has dozens, possibly as many as all other cities combined, but the lines built before 1930 only have one or two, the 3/L in East New York and maybe the 1/4-5 around South Ferry.

The upshot is that the optimal stop spacing depends on the line spacing. If the line spacing is tight – say this is Midtown Manhattan and there is a subway line underneath Lex/Park, Broadway, 6th, 7th, and 8th – then crossing lines have to have tight stop spacing in order to connect to all of these parallel lines. In the other direction, there were important streetcars on so many important cross-streets that it was desirable to intersect most or ideally all of them with transfers. With so many streetcar lines extending well past Midtown, it is not too surprising that there had to be frequent subway stops.

So why would denser cities have tighter line spacing?

Line spacing and density

The intuitive relationship between line spacing and density is that denser cities need more capacity, which requires them to build more rail lines.

To see this a bit more formally, think of an idealized city on a grid. Let’s say blocks are 100*100 meters, and the planners can figure out the target density in advance when designing the subway network. If the city is very compact, then the subway could even be a grid, at least locally. But now if we expect a low-density city, say 16 houses per block, then the subway grid spacing should be wide, since there isn’t going to be much traffic justifying many lines. As the city densifies, more subway is justifiable: go up to missing middle, which is around 30-40 apartments per block; then to the Old North of Tel Aviv, which would be around 80; then to a mid-rise euroblock, which is maybe 30-40 per floor and 150-200 per block; then finally a high-rise with maybe 500-1,000 apartments.

Each time we go up the density scale, we justify more subway. This isn’t linear – an area that fills 500 apartments per block, which is maybe 100,000 people per km^2, does not get 20 times the investment of an area on the dense side of single-family with 16 houses per block and 5,000 people per km^2. Higher density justifies intensification of service, with bigger and more frequent trains, as well as more crowding. With more subway lines, there are more opportunities for lines to intersect, leading to more frequent stop spacing.

Even if the first subway lines are not planned with big systems in mind, which New York’s wasn’t, the idea of connections to streetcar lines was historically important. A stop every 10 blocks, or 800 meters, was not considered on the local lines in New York early on; however, stops could be every 5 blocks or every 7, depending on the spacing of the major crosstown streets.

Dense blobs and linear density

Line spacing is important to stop spacing not on parallel lines, but crossing lines. If a bunch of lines go north-south close to one another, this by itself says little about the optimal spacing on north-south lines, but enforces tight spacing on east-west lines.

This means that high density encourages tight stop spacing when it is continuous in a two-dimensional area and not just a line. If large tracts of the city are very dense, then this provides justification for building a grid of subway, since the crosstown direction is likely to fill as well; in New York, 125th Street is a good candidate for continuing Second Avenue Subway Phase 2 as a crosstown line for this reason.

In contrast, if dense development follows a linear corridor, then there isn’t much justification for intense crosstown service. If there’s just one radial line, then the issue of line spacing is moot. Even if there are two closely parallel radial lines in the same area, a relatively linear development pattern means there’s no need for crosstown subways, since the two lines are within walking distance of each other. The radial urban and suburban rail networks of Tokyo and Seoul do not have narrow interstations, nor do they have much crosstown suburb-to-suburb service: density is high but follows linear corridors along rapid transit. Dense development in a finger plan does not justify much crosstown service, because there are big low-density gaps, and suburb-to-suburb traffic is usually served efficiently by trips on radial lines with a transfer in city center.

We Ran a Conference About Rail Modernization

The Modernizing Rail (Un)Conference happened last Sunday. We’re still gathering all the materials, but here are video uploads, including the keynote by Michael Schabas.

We will also have slides as given by presenters who used them. But for now, here are the slides used by the keynote. You may notice that the recording does not begin on the first slide; we missed Schabas’s introduction and some remarks on his background, detailing his 40 years of experience designing public transit systems in a number of countries, mainly Britain and Canada but also elsewhere in the developed world.

My session on construction costs was slide-free (and was not recorded), since I mostly just showed people around our under-construction cost dataset and answered a lot of questions. Some of those questions were annoying, by which I mean they questioned my thinking or brought up a point I haven’t considered before. I am not talking too much about it partly because I was mostly (mostly) repeating things I’ve said here, and the full database should be out later this summer, with all the mistakes I’ve made in currency conversion rates and in not updating for cost overruns fixed.

After my breakout, I was uncertain between which of two sessions to attend – one on HSR-legacy rail compatibility by María Álvarez, and one on equity issues in rail planning, by Grecia White and Ben She. I ended up going to the latter, which featured interesting discussions of inclusion of low-income people and minorities, both as riders (that is, serving people who are not middle-class whites better on regional rail) and as workers (that is, diversifying planning and engineering departments).

It went well in that there was no monopolization of discussion by people who have more a comment than a question, or any open racism or sexism; but it was somewhat frustrating in that while there was a lot of productive discussion of racial equality in rail planning, there was very little of gender equality even though we did intend to talk about both; Grecia was specifically interested in discussing these, for example women’s perceptions of public safety. This is in line with conference demographics – the organizing team and the breakout presenters were each one-third people of color, in line with US demographics; but the organizing team had 2/18 active women and the presenters 3/15. TransitMatters is similar in that regard – racial diversity is comparable to that of the Boston region, and the proportion of regulars who are queer is enormous, but there are very few women.

Finally, I hosted a session on how to set up a transport association, a.k.a. Verkehrsverbund. Christof Spieler did the most talking, and German attendees explained a lot about the difference between a transport association and agency amalgamation. But for the most part that session felt like an ersatz conclusion to the entire conference; it technically lasted an hour, but once the hour had lapsed, people from other sessions came to the room and the conversation continued naturally, talking a bit about different transit planning issues in Germany and a bit about applicability to rail reform in the Northeastern US.

More on the Deutschlandtakt

The Deutschlandtakt plans are out now. They cover investment through 2040, but even beforehand, there’s a plan for something like a national integrated timetable by 2030, with trains connecting the major cities every 30 minutes rather than hourly. But there are still oddities that are worth discussing, especially in the context of what Germans think trains are capable of and what is achieved elsewhere.

The key is the new investment plans. The longer-term plans aren’t too different from what I’ve called for. But somehow the speeds are lower. Specifically, Hamburg-Hanover is planned to be a combination of legacy rail (“ABS”) and newly-built high-speed rail (“NBS”), dubbed the Alpha-E project, with trains connecting the two cities in 63 minutes.

The point of an integrated takt timetable is that trains should connect major nodes (“knots”) in just less than an integer number of half-hours for hourly service, or quarter-hours for half-hourly service. Trains connect Zurich and Basel in 53 minutes and each of these two cities with Bern in 56 minutes, so that passengers can change trains on the hour and have short connections to onward destinations like Biel, St. Gallen, and Lausanne. To that effect, Switzerland spent a lot of money on tunnels toward Bern, to cut the trip time from somewhat more than an hour to just less than an hour. So the benefits of cutting trip times from 63 minutes to just less than an hour are considerable.

What’s more, it is not hard to do Hamburg-Hanover in less than an hour. Right now the railway is 181 km long, but the planned Alpha-E route is shorter – an alignment via the A 7 Autobahn would be around 145 km long. The Tokaido Shinkansen’s Hikari and Nozomi trains run nonstop between Nagoya and Kyoto, a distance of 134 km, in 34 minutes. Kodama trains make two additional stops, with long dwell times as there are timed overtakes there, and take 51 minutes. Shinkansen trains have better performance characteristics than ICE trains, but the difference in the 270-300 km/h range is around 25 seconds per stop, and the Tokaido Shinkansen is limited to 270 km/h whereas an Alpha-E NBS would do 300. So doing Hamburg-Hanover in less than 40 minutes is eminently possible.

Of course, major cities have slow approaches sometime… but Hamburg is not a bigger city than Kyoto or Nagoya. It’s about comparable in size to Kyoto, both city proper and metro area, and much smaller than Nagoya. Hanover is a lot smaller, comparable to cities served by Hikari but not Nozomi, like Shizuoka and Hamamatsu. Hamburg-Hanover has 12 km between Hamburg and Harburg where trains would be restricted to 140 km/h, and around 6 in Hanover where trains would be restricted to 130 km/h; in between they’d go full speed, which at the performance characteristics of the next-generation Velaro would be a little more than 35 minutes without schedule padding and maybe 38 minutes with. This fits well into a 45-minute slot in the takt, permitting both Hanover and Hamburg to act as knots.

Moreover, if for some reason a full NBS is not desirable – for example, if NIMBY lawsuits keep delaying the project – then it’s possible to built a partial NBS to fit into an hourly time slot, trains taking around 53 minutes. The cost per minute saved in this context is fairly consistent, as this is a flat area and the legacy line is of similar quality throughout the route; if for some reason the cost per minute saved is too high, e.g. if nuisance lawsuits raise construction costs above what they should be on such a route, which is around 15-20 million euros per kilometer, then going down only to 53 minutes is fine as it makes the hourly takt work well.

And yet, it’s not done. The biggest cities are not planned to have regular half-hourly knots, because there’s too much traffic there. But Hanover is in fact a perfect place for a knot, with trains going east to Berlin, west to the Rhine-Ruhr, north to Hamburg, and south to Frankfurt and the cities of Bavaria. Hamburg is at the northern margin of the country, with trains going mostly south to Hanover, but having some timed connection with trains continuing north to Kiel and eventually Copenhagen is not a bad idea.

For some reason, German rail activists, including presumably the ones who pushed the Deutschlandtakt from the bottom up while the ministry of transport was run by pro-car conservatives, are just too conservative about the capabilities of trains. I’ve seen one of the D-Takt groups, I forget which one, criticize plans to build an NBS between Hanover and Bielefeld, a segment on which the existing line is fairly slow, on the grounds that it could never fit into a knot system. It is not possible to do the roughly 100 km between Hanover and Bielefeld (actually closer to 95 km) in less than half an hour to fit a knot, they say – average speeds higher than 200 km/h are only found on very long nonstop stretches of high-speed rail, as in France, they insist. Shinkansen trains achieve such speeds over such segments every day, and even with the slightly lower performance characteristics of the next-generation Velaro, Hanover-Bielefeld in 24 technical minutes and 26 minutes with 7% pad (and the Shinkansen only has 4% pad) is feasible.

I genuinely don’t know why there is such conservatism among German rail planners and advocates. It could be that Europeans don’t like learning from Asia, just as Americans don’t like learning from Europe. There are examples of faster trains than in Germany within Europe, but maybe German advocates discount French and Spanish examples because of genuine problems with French and Spanish rail operations, leading them to also make excuses like “the trains run nonstop for 500 km and that’s why they’re fast” to avoid adopting the things where France and Spain are genuinely superior to Germany.

Nothing about the integrated timed transfer schedule idea impedes high speeds. On the contrary, in some cases, like Hanover-Hamburg but also the planned Frankfurt-Stuttgart line (already in place south of Mannheim), high speeds are necessary to make the desired knots. Moreover, where distances between cities are long compared with desired frequency, as on Berlin-Hanover, it’s possible to build 300 km/h lines and cut entire half hours or even full hours from trip times. Germany could innovate in this and build such a network for an amount of money well within the limits of the corona recovery package, which includes €50 billion for climate mitigation.

But either way, Germany is about to make mistakes of underinvestment because it’s not quite willing to see where the frontier of rail transport technology is. This is not the American amateur hour, it’s not the sort of situation where I can spend a few hours with maps and come up with better timetables myself, but even so, the plans here are far too timid for Germany’s medium- and long-term transportation needs.

The D-Takt is a step forward, don’t get me wrong. None of the investments I’m seeing is bad. But it’s a small, hesitant step forward rather than a firm, bold walk toward direction of intercity rail modernization. A country that expects intercity rail ridership to double, putting Germany’s per capita intercity rail ridership in the vicinity of Japan’s, should have something similar to the Shinkansen network, with a connected network of NBS links between the major cities averaging 200-250 km/h and not 120-160 km/h.

The French Way of Building Rapid Transit

It’s been a while since I last wrote this series, where I covered the American, Soviet, and British traditions of building urban rail. I’d like to return by focusing attention on the French tradition, which has been influential not just within France itself but also to some extent former French colonies, especially Quebec.

An issue I hope to return to soon is the extent to which France has not truly decolonized; former French colonies in Africa, especially the Maghreb, rely on French technical expertise for construction, and often outsource their monetary policy (as with the CFA franc, but Morocco too has a peg to a dollar and euro mix). This matters, because this means the French way of building urban transit is influential in former French colonies in Africa, whereas the British tradition’s impact on India, Nigeria, and so on is limited.

The history of Paris

Like Britain, the USSR, and the US, France has a dominant financial center that its smaller cities aim to imitate. This imitation has been much more extensive than in the US and UK – to the extent that secondary French cities diverge in design principles from the capital, they do things that were fashionable in Paris at the time they built out their rail networks rather than things that were fashionable in Paris when Paris built the Métro. Thus, it is especially valuable to look at the history of urban rail in Paris.

The Paris Métro opened in 1900, as the world’s fifth metro system. Already then, it had a critical feature that the previous four (London, Budapest, Chicago, Glasgow) lacked: it was a centrally planned multi-line system. The city planned a coordinated system of what would become Lines 1-6, in the shape of a # in a circle: Lines 1 and 3 would run east-west, Lines 4 and 5 would run north-south, and Line 2, eventually split into Lines 2 and 6, would run the trace of the wall that delineated the city’s pre-1860 boundary.

The Métro was a municipal effort run by the municipal CMP, designed around the city’s needs, which included not just good transportation but also separation from the working-class suburbs. Whereas the London Underground was mostly technologically compatible with the mainline system, the Métro was deliberately designed not to be, to protect the urban middle class from transport integration with the suburban poor. This led to the following features:

  • The trains are extremely narrow, 2.4-2.44 meters wide, compared with about 2.9 m on the mainline; the deep Tube trains in London, held to have the narrowest loading gauge on a standard-gauge railway, are 2.68 m wide.
  • The interstation distance is very short, 562 meters on average. Paris is compact and dense and the short interstations are only a real problem in the suburbs.
  • The trains run on the right, like French road traffic, whereas French trains run on the left.
  • No legacy lines were incorporated into the system, unlike in New York and London, and thus the shape of the network looks much more like how one would design a metro network from scratch and less like how old West London branches or Brooklyn excursion lines looked.

Like New York and Berlin and unlike London, Paris built the Métro cut-and-cover. The lines built before the 1990s all closely follow streets except when they cross the river – and in the 1900s the Line 4 river crossing was the hardest part of the system to build, opening in 1908 whereas the rest of the network had opened by 1906. This was done entirely by hand, forcing the lines to curve where the streets did, which led to two notable warts. First, while most of the system had a design standard of 60 meter curve radii, Line 1 goes down to 40 at Bastille. And second, Line 5, which crosses the Seine on a bridge, cannot serve Gare de Lyon; the engineers could not get it to curve that way while still running through to Gare d’Austerlitz and the Left Bank, so instead the transfer point between Lines 1 and 5 is Bastille, and more recently the RER A and Line 14 both cross Line 5 without a transfer as they run express from Gare de Lyon to Châtelet.

That said, the missed connection between Lines 5 and 14 is the only one in the system, though two more are under construction on Line 14 extensions. Only one among the major metro systems of the world runs entirely without missed connections, the Mexico City Metro, which has unusually low line density in the core and unusually many tangential lines.

The suburbs and the RER

The Métro’s deliberate exclusion of the suburbs made sense from the point of view of a middle-class Parisian in 1900 who was mortally afraid of the working class. But by the 1930s, it was leading to serious design constraints. Further Métro extensions both densified the network and extended it outward, and in the 1930s, lines began to extend past city limits, to such suburbs as Lilas, Issy, Neuilly, and Montreuil. The short interstations made longer extensions infeasible, and some solution involving regional rail was needed.

In 1938, CMP bought and electrified the Ligne de Sceaux, which alone among the Paris commuter lines had reached close to city center, terminating at Jardin du Luxembourg rather than at the farther away rail stations, which are located at or just inside the M2/M6 ring. Then after the war, as suburbanization intensified and commuter traffic at Gare Saint-Lazare grew increasingly congested, CMP’s successor RATP collaborated with SNCF on connecting regional rail branches to form an express system, that is the RER; the Ligne de Sceaux became the southern half of the RER B, while a similar branch going east paired with one of the Saint-Lazare lines to form the RER A. Through-service opened in 1977, roughly at the same time as the German S-Bahn through-tunnels, but the system grew much larger as Paris was and remains far larger than any German city.

But it is not exactly correct to view the RER as identical to a German S-Bahn, or to one of the RER’s inspirations, the Tokyo through-running system. A number of features characterize it, some shared with other urban regional rail systems, some not:

  • There are multiple trunk lines through the city, which form something like a coherent network among themselves, and do not share rolling stock. The biggest warts are that the RER B and D share tracks (but no platforms) on one interstation, and that the RER C mostly stays on the Left Bank, legacy of when planning in Paris conceived of the area around Saint-Michel as a central area to be served, where in reality it is decidedly secondary to the CBD stretching from Les Halles to Champs-Elysées.
  • It runs largely, though not entirely, on separate tracks from non-RER lines.
  • It is locally viewed as deficient to Métro service – researchers who use the RER B to get to IHES think of it as lower-quality, lower-class service than the Métro in the city and its immediate suburbs. I suspect that this is why Grand Paris Express is designed around Métro standards rather than as intensification of RER service, while RER expansion has fallen to the wayside.
  • RER-Métro integration is imperfect: the fares are integrated but there are still barriers between RER and Métro platforms, and there are many missed RER-Métro connections, whereas in Berlin the S-Bahn and U-Bahn have only one missed connection between them.
  • The interstation is around 2-3 km, but it’s actually slightly longer on the new urban tunnels build for the RER A, B, D, and E than on the legacy lines in the inner suburbs; this feature also exists in a much more extreme form in the United States, but in Berlin and Tokyo it is completely absent.

Exporting Parisian ideas

Parisian metro planning influenced Montreal, Mexico City, and the smaller French cities, in chronological order. We see any of the following features in those cities:

  • Rubber-tired metros. This technology was in vogue in postwar Paris, which converted Lines 1, 4, and 11 to it figuring this was just better than steel wheels, and also Line 6, figuring that an elevated line would benefit from a quieter propulsion system.
  • Non-radial network design. London and the systems inspired by it, including all Eastern bloc systems, have radial design, with nearly all lines entering a relatively small city center. Paris expanded its #-in-a-circle system to a combination of a radial network and a grid, with a large number of pairs of parallel lines. Mexico City, the largest system inspired by Paris, is rich in tangential lines but has only three lines serving city center, which are by far the three busiest.
  • Short interstations, though this is truer domestically than in Montreal and Mexico City.
  • Driverless operations. This technology became popular in the 1980s, starting with the Lille Metro, and France has used it on new lines in Paris (M14) and elsewhere (Lyon Line D, both lines in Toulouse), also innovating in converting manual lines to automatic on Paris M1 and now M4. While the Parisian lines are full-size metro lines, the other ones are light metro running shorter vehicles, often with extensive elevated service.
  • Separation between regional rail and metro service. Montreal is sufficiently North American to have given up on regional rail entirely, but Lyon and Marseille are investing in better regional rail, run separately from the local urban transit system but with some degree of integration.
  • Light rail. France’s modern light rail systems do not originate in Paris – Nantes opened its system in 1985, suburban Paris only in 1992 – but Paris has a notable feature that isn’t common elsewhere in Western Europe: it is a mixed system with some Métro lines and some tram lines filling in the gaps. This mixed system is also present in Lyon, Marseille, and Toulouse, whereas Bordeaux, Strasbourg, and Nice have entirely tram-centric systems. But in no case is there any subway-surface running as in the United States or Germany: lines are either clearly trams or clearly metros, rather than mixtures, and it is the system that is mixed, not the individual line.

Has France decolonized?

Like Britain, France did not take its geopolitical disempowerment at the end of World War Two easily. Both countries have maintained superpower pretensions, decolonizing but trying to treat their former colonies as their spheres of influence as much as possible. In Britain, this relationship broke down – the ex-colonies were being too loud in the Commonwealth, leading the country to seek to join the EU instead. In France, this relationship remains in Africa, and notable not in Southeast Asia, where Vietnam is buildings its urban rail networks with Chinese and Japanese financing.

But France is not just providing financing to infrastructure projects in its former (or current?) African colonies. It has a permanent presence. In researching Arab rail infrastructure, Anan Maalouf has noted that Alstom has had a subsidiary operating in Algeria since 2002, which does not exist elsewhere in the Arab world. This way, French firms maintain close knowledge of the situation in the Maghreb, where incomes and productivity levels are much lower than in France, so that different methods are optimal from those common in rich countries.

Nonetheless, what they build remains noticeably French. For example, the Sfax tramway does not look too different from what Bordeaux or Nice has. The Tunis Métro looks rather like a French tramway system too, despite the name; of note, even though the Tunis Métro branches, and has some underground segments, those segments are not on line trunks and thus the system does not form a subway-surface or Stadtbahn network.

I haven’t gone too much into intercity rail, but it is worth mentioning that Morocco has a high-speed rail system, built with French technical assistance and running TGV equipment.

Does this work?

Yes and no.

The Paris system works. It is not perfect, and in particular the integration between the Métro and the RER could be better; at least one tram line should be a full metro line (a completed T3 ring), and suburban extensions should generally use the RER, with more investment in RER capacity within the city as well. That said, public transport usage is higher in Paris than in its closest comparison, that is London; Paris’s system is also superior in both overall usage and future prospects to that of another megacity in Europe, Moscow. Only Istanbul could potentially do better in the future, in the context of extremely low construction costs.

That said, Paris is a giant that casts a long shadow, which doesn’t always work well for secondary cities. Lyon, Marseille, Toulouse, and the other secondary French cities aren’t too different in modal split from similar-size British cities, and are behind Vancouver, a North American city with extensive postwar growth. German cities in the Lyon size class do a lot better. See for example data here and here.

The weird features of France, like the love for rubber tires, are not that relevant overall, but do point out that France is relatively insular, and mostly adopts domestic ideas developed in Paris rather than ideas from elsewhere in Europe, let alone Asia. (Yes, I know about Japanese influence on the initial RER; however, there have been 50 years of divergence since, same as with German tram-trains and American light rail.) This has been especially problematic with regional rail. France does not have frequent takts anywhere – even Paris only has takt timetables off-peak, running a separate schedule at rush hour, whereas the German takt plan is repeated throughout the day and the peak can only have supplemental service.

The issue is that Paris does not need to think in terms of repeating schedules, because it is so big that the RER trunks run every 5 minutes off-peak. It thinks of the RER as mostly separate trunk lines with dedicated fleets, because the primary problem is train capacity through city center. In Lyon, let alone smaller cities, this is not the main issue. There do exist a handful of individual lines running an off-peak takt elsewhere in France, but integration with urban rail remains imperfect and a comparison with Vienna, Copenhagen, Zurich, Stuttgart, and Hamburg would not be favorable. It matters that, like Britain, France has such a dominant capital that it doesn’t know how to scale down to provide rail service in a metropolitan area where if the transfers aren’t perfectly timed, people won’t ride.

Modernizing Rail Unconference

On Sunday the 12th of July, a few of us public transit activists are going to hold a conference online called Modernizing Rail, focusing on better service and integration in the Northeastern United States. Our keynote speaker will be Vukan Vuchic, the Serbian-American UPenn transportation professor who imported German rail modernization schemas from the 1970s, including the concept of regional rail; he will speak about the history of this in the context of SEPTA, which built much of the S-Bahn infrastructure (e.g. S-Bahn through-running tunnel) but has not done many other important things such as fare integration and coordinated planning with urban transit.

Update 2020-07-04: due to a family health emergency, Vuchic cannot make it. Therefore we will have an alternate keynote address by Michael Schabas, entitled Using Business Case Analysis to Design Better Railways.

Schabas has been finding ways to make railways deliver more and cost less for 40 years, shaping urban, intercity, and high speed rail projects in Canada, England, and the USA, and operating passenger and freight railways in England and Australia. He is the author of The Railway Metropolis – how planners, politicians and developers shaped Modern London. Since 2014 he has been advising Toronto’s Metrolinx on the $20 billion upgrading and electrification of the GO Rail system, and the $28.5 billion expansion of Toronto’s subway system. Michael is a Partner in FCP, a rail strategy boutique based in the UK advising clients on rail developments and projects around the world

The keynote will be between 11 am and noon Eastern time.

After the keynote, we will hold unconference-style sessions. For people who have not seen this style before, this means that we solicit ideas from the entire body of attendees for breakout sessions, and then by consensus, depending on the number of attendees and what they are interested in, split into rooms for further discussion of the selected topics. There will be three slots for breakouts: 1-2, 2:15-3:15, 3:30-4:30 pm, all Eastern time; the number of breakouts will depend greatly on the number of attendees, which at this point we are uncertain about. The breakouts may include pure discussions or presentations, and we also solicit expressions of interest in presenting if there’s an issue you have particular interest and expertise in.

There will be more information available on social media, but to register, please complete this form. You can create an account on Journey for this if you’d like, in which case you can save your progress and come back later, but this is not a long form and you can complete it in one go without registration.

The conference will be held on Zoom, with link emailed shortly before the event takes place.

Update 2020-07-11: here is the timetable. Email us at for the Zoom password if you’ve registered.

Some Notes About Northeast Corridor High-Speed Rail

I want to follow up on what I wrote about speed zones a week ago. The starting point is that I have a version 0 map on Google Earth, which is far from the best CAD system out there, one that realizes the following timetable:

Boston 0:00
Providence 0:23
New Haven 1:00
New York 1:40
Newark 1:51
Philadelphia 2:24
Wilmington 2:37
Baltimore 3:03
Washington 3:19

This is inclusive of schedule contingency, set at 7% on segments with heavy track sharing with regional rail, like New York-New Haven, and 4% on segment with little to no track haring, like New Haven-Providence. The purpose of this post is to go over some delicate future-proofing that this may entail, especially given that the cost of doing so is much lower than the agency officials and thinktank planners who make glossy proposals think it should.

What does this entail?

The infrastructure required for this line to be operational is obtrusive, but for the most part not particularly complex. I talked years ago about the I-95 route between New Haven and southern Rhode Island, the longest stretch of new track, 120 km long. It has some challenging river crossings, especially that of the Quinnipiac in New Haven, but a freeway bridge along the same alignment opened in 2015 at a cost of $500 million, and that’s a 10-lane bridge 55 meters wide, not a 2-track rail bridge 10 meters wide. Without any tunnels on the route, New Haven-Kingston should cost no more than about $3-3.5 billion in 2020 terms.

Elsewhere, there are small curve easements, even on generally straight portions like in New Jersey and South County, Rhode Island, both of which have curves that if you zoom in close enough and play with the Google Earth circle tool you’ll see are much tighter than 4 km in radius. For the most part this just means building the required structure, and then connecting the tracks to the new rather than old curve in a night’s heavy work; more complex movements of track have been done in Japan on commuter railroads, in a more constrained environment.

There’s a fair amount of taking required. The most difficult segment is New Rochelle-New Haven, with the most takings in Darien and the only tunneling in Bridgeport; the only other new tunnel required is in Baltimore, where it should follow the old Great Circle Tunnel proposal’s scope, not the four-track double-stack mechanically ventilated bundle the project turned into. The Baltimore tunnel was estimated at $750 million in 2008, maybe $1 billion today, and that’s high for a tunnel without stations – it’s almost as high per kilometer as Second Avenue Subway without stations. Bridgeport requires about 4 km of tunnel with a short water crossing, so figure $1-1.5 billion today even taking the underwater penalty and the insane unit costs of the New York region as a given.

A few other smaller deviations from the mainline are worth doing at-grade or elevated: a cutoff in Maryland near the Delaware border in the middle of what could be prime 360 km/h territory, a cutoff in Port Chester and Greenwich bypassing the worst curve on the Northeast Corridor outside major cities, the aforementioned takings-heavy segment through Darien continuing along I-95 in Norwalk and Westport, a short bypass of curves around Fairfield Station. These should cost a few hundred million dollars each, though the Darien-Westport bypass, about 15 km long, could go over $1 billion.

Finally, the variable-tension catenary south of New York needs to be replaced with constant-tension catenary. A small portion of the line, between New Brunswick and Trenton, is being so replaced at elevated cost. I don’t know why the cost is so high – constant-tension catenary is standard around the world and costs $1.5-2.5 million per km in countries other than the US, Canada, and the UK. The Northeast Corridor is four-track and my other examples are two-track, but then my other examples also include transformers and not just wires; in New Zealand, the cost of wires alone was around $800,000 per km. Even taking inflation and four tracks into account, this should be maybe $700 million between New York and Washington, working overnight to avoid disturbing daytime traffic.

The overall cost should be around $15 billion, with rolling stock and overheads. Higher costs reflect unnecessary scope, such as extra regional rail capacity in New York, four-tracking the entire Providence Line instead of building strategic overtakes and scheduling trains intelligently, the aforementioned four-track version of the Baltimore tunnel, etc.

The implications of cheap high-speed rail

I wrote about high-speed rail ridership in the context of Metcalfe’s law, making the point that once one line exists, extensions are very high-value as a short construction segment generates longer and more profitable trips. The cost estimate I gave for the Northeast Corridor is $13 billion, the difference with $15 billion being rolling stock, which in that post I bundled into operating costs. With that estimate, the line profits $1.7 billion a year, a 13% financial return. This incentivizes building more lines to take advantage of network effects: New Haven-Springfield, Philadelphia-Pittsburgh, Washington-Virginia-North Carolina-Atlanta, New York-Upstate.

The problem: building extensions does require the infrastructure on the Northeast Corridor that I don’t think should be in the initial scope. Boston-Washington is good for around a 16-car train every 15 minutes all day, which is very intense by global standards but can still fit in the existing infrastructure where it is two-track. Even 10-minute service can sometimes fit on two tracks, for example having some high-speed trains stop at Trenton to cannibalize commuter rail traffic – but not always. Boston-Providence every 10 minutes requires extensive four-tracking, at least from Attleboro to beyond Sharon in addition to an overtake from Route 128 to Readville, the latter needed also for 15-minute service.

More fundamentally, once high-speed rail traffic grows beyond about 6 trains per hour, the value of a dedicated path through New York grows. This is not a cheap path – it means another Hudson tunnel, and a connection east to bypass the curves of the Hell Gate Bridge, which means 8 km of tunnel east and northeast of Penn Station and another 2 km above-ground around Randall’s Island, in addition to 5 km from Penn Station west across the river. The upshot is that this connection saves trains 3 minutes, and by freeing trains completely from regional rail traffic with four-tracking in the Bronx, it also permits using the lower 4% schedule pad, saving another 1 minute in the process.

If the United States is willing to spend close to $100 billion high-speed rail on the Northeast Corridor – it isn’t, but something like $40-50 billion may actually pass some congressional stimulus – then it should spend $15 billion and then use the other $85 billion for other stuff. This include high-speed tie-ins as detailed above, as well as low-speed regional lines in the Northeast: new Hudson tunnels for regional traffic, the North-South Rail Link, RegionalBahn-grade links around Providence and other secondary cities, completion of electrification everywhere a Northeastern passenger train runs

Incremental investment

I hate the term “incremental” when it comes to infrastructure, not because it’s inherently bad, but because do-nothing politicians (e.g. just about every American elected official) use it as an excuse to implement quarter-measures, spending money without having to show anything for it.

So for the purpose of this post, “incremental” means “start with $15 billion to get Boston-Washington down to 3:20 and only later spend the rest.” It doesn’t mean “spend $2 billion on replacing a bridge that doesn’t really need replacement.”

With that in mind, the capacity increases required to get from bare Northeast Corridor high-speed rail to a more expansive system can all be done later. The overtakes on Baltimore-Washington would get filled in to form four continuous tracks all the way, the ones on Boston-Providence would be extended as outlined above, the bypasses on New York-New Haven would get linked to new tracks in the existing right-of-way where needed, the four-track narrows between Newark and Elizabeth would be expanded to six in an already existing right-of-way. Elizabeth Station has four tracks but the only building in the way of expanding it to six is a parking garage that needs to be removed anyway to ease the S-curve to the south of the platforms.

However, one capacity increase is difficult to retrofit: new tracks through New York. The most natural way to organize Penn Station is as a three-line system, with Line 1 carrying the existing Hudson tunnel and the southern East River tunnels, including high-speed traffic; Line 2 using new tunnels and a Grand Central link; and Line 3 using a realigned Empire Connection and the northern East River tunnels. The station is already centered on 32nd Street extending a block each way; existing tunnels going east go under 33rd and 32nd, and all plans for new tunnels continuing east to Grand Central or across the East River go under 31st.

But if it’s a 3-line system and high-speed trains need dedicated tracks, then regional trains don’t get to use the Hell Gate Line. (They don’t today, but the state is spending very large sums of money on changing this.) Given the expansion in regional service from the kind of spending that would justify so much extra intercity rail, a 4-line system may be needed. This is feasible, but not if Penn Station is remodeled for 3 lines; finding new space for a fourth tunnel is problematic to say the least.


The point of integrated timetable planning is to figure out what timetable one want to run in the future and then building the requisite infrastructure. Thus, in the 1990s Switzerland built the tunnels and extra tracks for the connections planned in Bahn 2000, and right now it’s doing the same for the next generation. This can work incrementally, but only if one knows all the phases in advance. If timetable plans radically change, for example because the politicians make big changes overruling the civil service to remind the public that they exist, then this system does not work.

If the United States remains uninterested in high-speed rail, then it’s fine to go ahead with a bare-bones $15 billion system. It’s good, it would generate good profits for Amtrak, it would also help somewhat with regional-intercity rail connectivity. Much of the rest of the system can be grafted on top without big changes.

But then it comes to Penn Station. It’s frustrating, because anything that brings it into focus attracts architects and architecture critics who think function should follow form. But it’s really important to make decisions soon, get to work demolishing the above-ground structures starting when the Madison Square Garden lease runs out, and move the tracks in the now-exposed stations as needed based on the design timetable.

As with everything else, it’s possible not to do it – to do one design and then change to another – but it costs extra, to the tune of multiple billions in unnecessary station reconstruction. If the point is to build high-speed rail cost-effectively, spending the same budget on more infrastructure instead of on a few gold-plated items, then this is not acceptable. Prior planning of how much service is intended is critical if costs are to stay down.