Shaul Picker is working on an FAQ for the benefit of people in the New York area about the concept of commuter rail through-running and what it’s good for. So in addition to contributing on some specific points, I’d like to step back for a moment and go over who the expected users are. This post needs to be thought of as a followup from what I wrote a month ago in which I listed the various travel markets used by modern commuter rail in general, making the point that this is a predominantly urban and inner-suburban mode, in which suburban rush hour commuters to city center are an important but secondary group, even where politically commuter rail is conceived of as For the Suburbs in opposition to the city, as in Munich. My post was about all-day frequency, but the same point can be made about the physical infrastructure for through-running, with some modifications.
The overall travel markets for regional rail
The assumption throughout is that the city region has with a strong center. This can come from a few square kilometers of city center skyscrapers, as is the norm in the United States (for example, in New York, Chicago, or Boston, but not weaker-centered Los Angeles), or from a somewhat wider region with office mid-rises, as is the norm in European cities like Paris, Stockholm, Munich, Zurich, and Berlin. Berlin is polycentric in the sense of having different job centers, including Mitte, City-West at the Zoo, and increasingly Friedrichshain at Warschauer Strasse, but these are all within the Ring, and overall this inner zone dominates citywide destinations. In cities like this, the main travel markets for commuter rail are, in roughly descending order of importance,
- Urban commuter trips to city center
- Commuter trips to a near-center destination, which may not be right at the one train station of traditional operations
- Urban non-work trips, of the same kind as subway ridership
- Middle-class suburban commutes to city center at traditional mid-20th century work hours, the only market the American commuter rail model serves today
- Working-class reverse-commutes, not to any visible office site (which would tilt middle-class) but to diffuse retail, care, and service work
- Suburban work and non-work trips to city center that are not at traditional mid-20th century hours
- Middle-class reverse-commutes and cross-city commutes
I center urban commuter trips because even in places with extensive suburbanization, commutes are more urban than suburban. Long Island, an unusually job-poor, commuter-oriented suburb, has 2.9 million people as of the 2020 census and, per OnTheMap, 191,202 Manhattan-bound commuters and 193,536 outer borough-bound commuters. Queens has 2.4 million people, 871,253 in-city commuters, 384,223 Manhattan-bound commuters, and 178,062 commuters to boroughs other than itself and Manhattan. The Metro-North suburbs – Westchester, Putnam, Dutchess, and Fairfield Counties (New Haven omitted as it’s not really a suburb) – have 2.35 million people and 143,862 Manhattan-bound commuters and 79,821 outer borough-bound commuters. To work regionwide, commuter rail needs to be usable by the largest commute market; it’s urban rail that’s capable of also serving the suburbs without building suburban metro tunnels, rather than predominantly suburban rail.
Through-running means that trains run from one side of the region to the other through city center, rather than terminating at a traditional city terminal. Rarely, this means running trains through a city center station that already has through-tracks, like Penn Station or Stockholm Central; usually, this requires building new tunnels to connect different terminals, as it would to get to Grand Central and as it did in the other European comparison cases.
This rearranges the travel markets for commuter rail, but only somewhat. The largest group, urban commuters to city center, shrinks somewhat: terminating trains to some extent already serve it. The qualifiers come from the fact that city center is rarely entirely within walking distance of the terminal; it is in Stockholm, but it’s small and I suspect the reason Stockholm’s monocentric CBD is walking distance from the intercity station is that it opened as a through-station in 1871 already. In Boston, most of the CBD is close to South Station, but much of it isn’t, and little is within walking distance of North Station. In New York, the CBD is large enough that service to multiple destinations is desirable when feasible, for example both East Side and West Side destinations in Midtown and even Lower Manhattan, requiring additional through-running commuter rail tunnels.
What really shines with through-running is urban trips that are not commutes, or are commutes to a near-center destination on the wrong side of the CBD (for example, south of it for commuters from Uptown Manhattan or the Bronx). New York is unusually asymmetric in that there’s much more city east of Manhattan than west of it, where there’s just the urban parts of Hudson County and Newark. But even there, New Jersey-Brooklyn and New Jersey-Queens commutes matter, as do Bronx-Brooklyn commutes.
Even then, the urban commutes are significant: there are 55,000 commuters from the Bronx to Manhattan south of 23rd Street. These in-city travel markets are viable by subway today, but are for the most part slow even on the express trains – the A train’s run from Inwood to Jay Street and the 4’s run from Woodlawn to Brooklyn Bridge are both scheduled to take 45 minutes for 22.5 km, an average speed of 30 km/h. And then the New Jersey-to-outer borough commutes are largely unviable by public transportation – they cost double because there’s no fare integration between PATH and the subway and the transfers are onerous and slow, and besides, PATH’s coverage of the urban parts of North Jersey leaves a lot to be desired.
Adapting the city
Berlin is in a way the most S-Bahn-oriented city I know of. It’s polycentric but all centers are within the Ring and close to either the Stadtbahn or (for Potsdamer Platz) the North-South Tunnel. This shouldn’t be surprising – the Stadtbahn has been running since the 1880s, giving the city time to adapt to it, through multiple regime changes, division, and reunification. Even Paris doesn’t quite compare – the RER’s center, Les Halles, is a retail but not job center, and the five-line system only has two CBD stops, the RER A’s Auber and the RER E’s Haussmann-Saint-Lazare.
Can New York become more like Berlin if it builds through-running? The answer is yes. Midtown would remain dominant, and overall the region would become less rather than more polycentric as better commuter rail service encouraged job growth in the Manhattan core. But it’s likely any of the following changes would grow the market for commuter rail to take advantage of through-running over time:
- Job growth in Lower Manhattan, which has struggled with office vacancy for decades
- Job growth in non-CBD parts of Manhattan that would become accessible, like Union Square, or even Midtown South around Penn Station, which is lower-rise than the 40s and 50s
- Job growth in near-center job centers – Downtown Brooklyn may see a revival, and Long Island City is likely to see a larger upswing than it is already seeing if it becomes more accessible from New Jersey and not just the city
- Residential location adjustment – Brooklyn workers may choose to depend on the system and live in the Bronx or parts of New Jersey with good service instead of moving farther out within Brooklyn or suburbanizing and driving to work
- Residential transit-oriented development near outlying stations, in urban as well as suburban areas
I’d like to discuss a bypass of Philadelphia, as a followup from my previous post, about high-speed rail and passenger traffic density. To be clear, this is not a bypass on Northeast Corridor trains: every train between New York and Washington must continue to stop in Philadelphia at 30th Street Station or, if an in my opinion unadvised Center City tunnel is built, within the tunnel in Center City. Rather, this is about trains between New York and points west of Philadelphia, including Harrisburg, Pittsburgh, and the entire Midwest. Whether the bypass makes sense depends on traffic, and so it’s an example of a good investment for later, but only after more of the network is built. This has analogs in Germany as well, with a number of important cities whose train stations are terminals (Frankfurt, Leipzig) or de facto terminals (Cologne, where nearly all traffic goes east, not west).
Philadelphia and Zoo Junction
Philadelphia historically has three mainlines on the Pennsylvania Railroad, going to north to New York, south to Washington, and west to Harrisburg and Pittsburgh. The first two together form the southern half of the Northeast Corridor; the third is locally called the Main Line, as it was the PRR’s first line.
Trains can run through from New York to Washington or from Harrisburg to Washington. The triangle junction northwest of the station, Zoo Junction, permits trains from New York to run through to Harrisburg and points west, but they then have to skip Philadelphia. Historically, the fastest PRR trains did this, serving the city at North Philadelphia with a connection to the subway, but this was in the context of overnight trains of many classes. Today’s Keystone trains between New York and Harrisburg do no such thing: they go from New York to Philadelphia, reverse direction, and then go onward to Harrisburg. This is a good practice in the current situation – the Keystones run less than hourly, and skipping Philadelphia would split frequencies between New York and Philadelphia to the point of making the service much less useful.
When should trains skip Philadelphia?
The advantage of skipping Philadelphia are that trains from New York to Harrisburg (and points west) do not have to reverse direction and are therefore faster. On the margin, it’s also beneficial for passengers to face forward the entire trip (as is typical on American and Japanese intercity trains, but not European ones). The disadvantage is that it means trains from Harrisburg can serve New York or Philadelphia but not both, cutting frequency to each East Coast destination. The effect on reliability and capacity is unclear – at very high throughput, having more complex track sharing arrangements reduces reliability, but then having more express trains that do not make the same stop on the same line past New York and Newark does allow trains to be scheduled closer to each other.
The relative sizes of New York, Philadelphia, and Washington are such that traffic from Harrisburg is split fairly evenly between New York on the other hand and Philadelphia and Washington on the other hand. So this really means halving frequency to each of New York and Philadelphia; Washington gets more service with split service, since if trains keep reversing direction, there shouldn’t be direct Washington-Harrisburg trains and instead passengers should transfer at 30th Street.
The impact of frequency is really about the headway relative to the trip time. Half-hourly frequencies are unconscionable for urban rail and very convenient for long-distance intercity rail. The headway should be much less than the one-way trip time, ideally less than half the time: for reference, the average unlinked New York City Subway trip was 13 minutes in 2019, and those 10- and 12-minute off-peak frequencies were a chore – six-minute frequencies are better for this.
The current trip time is around 1:20 New York-Philadelphia and 1:50 Philadelphia-Harrisburg, and there are 14 roundtrips to Harrisburg a day, for slightly worse than hourly service. It takes 10 minutes to reverse direction at 30th Street, plus around five minutes of low-speed running in the station throat. Cutting frequency in half to a train every two hours would effectively add an hour to what is a less than a two-hour trip to Philadelphia, even net of the shorter trip time, making it less viable. It would eat into ridership to New York as well as the headway rose well above half the end-to-end trip, and much more than that for intermediate trips to points such as Trenton and Newark. Thus, the current practice of reversing direction is good and should continue, as is common at German terminals.
What about high-speed rail?
The presence of a high-speed rail network has two opposed effects on the question of Philadelphia. On the one hand, shorter end-to-end trip times make high frequencies even more important, making the case for skipping Philadelphia even weaker. In practice, high speeds also entail speeding up trains through station throats and improving operations to the point that trains can change directions much faster (in Germany it’s about four minutes), which weakens the case for skipping Philadelphia as well if the impact is reduced from 15 minutes to perhaps seven. On the other hand, heavier traffic means that the base frequency becomes much higher, so that cutting it in half is less onerous and the case for skipping Philadelphia strengthens. Already, a handful of express trains in Germany skip Leipzig on their way between Berlin and Munich, and as intercity traffic grows, it is expected that more trains will so split, with an hourly train skipping Leipzig and another serving it.
With high-speed rail, New York-Philadelphia trip times fall to about 45 minutes in the example route I drew for a post from 2020. I have not done such detailed work outside the Northeast Corridor, and am going to assume a uniform average speed of 240 km/h in the Northeast (which is common in France and Spain) and 270 km/h in the flatter Midwest (which is about the fastest in Europe and is common in China). This means trip times out of New York, including the reversal at 30th Street, are approximately as follows:
Out of both New York and Philadelphia, my gravity model predicts that the strongest connection among these cities is by Pittsburgh, then Cleveland, then Chicago, then Detroit, then Harrisburg. So it’s best to balance the frequency around the trip time to Pittsburgh or perhaps Cleveland. In this case, even hourly trains are not too bad, and half-hourly trains are practically show-up-and-go frequency. The model also predicts that if trains only run on the Northeast Corridor and as far as Pittsburgh then traffic fills about two hourly trains; in that case, without the weight of longer trips, the frequency impact of skipping Philadelphia and having one hourly train run to New York and Boston and another to Philadelphia and Washington is likely higher than the benefit of reducing trip times on New York-Harrisburg by about seven minutes.
In contrast, the more of the network is built out, the higher the base frequency is. With the Northeast Corridor, the spine going beyond Pittsburgh to Detroit and Chicago, a line through Upstate New York (carrying Boston-Cleveland traffic), and perhaps a line through the South from Washington to the Piedmont and beyond, traffic rises to fill about six trains per hour per the model. Skipping Philadelphia on New York-Pittsburgh trains cuts frequency from every 10 minutes to every 20 minutes, which is largely imperceptible, and adds direct service from Pittsburgh and the Midwest to Washington.
Building a longer bypass
So far, we’ve discussed using Zoo Junction. But if there’s sufficient traffic that skipping Philadelphia shouldn’t be an onerous imposition, it’s possible to speed up New York-Harrisburg trains further. There’s a freight bypass from Trenton to Paoli, roughly following I-276; a bypass using partly that right-of-way and, where it curves, that of the freeway, would require about 70 km of high-speed rail construction, for maybe $2 billion. This would cut about 15 km from the trip via 30th Street or 10 km via the Zoo Junction bypass, but the tracks in the city are slow even with extensive work. I believe this should cut another seven or eight minutes from the trip time, for a total of 15 minutes relative to stopping in Philadelphia.
I’m not going to model the benefits of this bypass. The model can spit out an answer, which is around $120 million a year in additional revenue from faster trips relative to not skipping Philadelphia, without netting out the impact of frequency, or around $60 million relative to skipping via Zoo, for a 3% financial ROI; the ROI grows if one includes more lines in the network, but by very little (the Cleveland-Cincinnati corridor adds maybe 0.5% ROI). But this figure has a large error bar and I’m not comfortable using a gravity model for second-order decisions like this.
All large urban rail networks rely on transfers – there are too many lines for direct service between any pair of stations. However, transfers are still usually undesirable; there is a transfer penalty, which can be mitigated but not eliminated. This forces the planners who design urban and suburban rail systems to optimize: too many transfers and the trips are too inconvenient, too few and the compromises required to avoid transfers are also too inconvenient. How do they do it? And why?
Of note, the strategies detailed below are valid for both urban rail and suburban commuter rail systems. Multi-line commuter rail networks like the RER and the Berlin S-Bahn tend to resemble urban rail in their core and work in conjunction with the rest of the urban rail network, and therefore strategies for reducing the onerousness of transferring work in much the same way for both kinds of systems. Suburban strategies such as timing half-hourly trains to meet connecting buses are distinct and outside the scope of this post.
Passengers universally prefer to avoid transfers between vehicles, keeping everything else constant. The transportation studies literature has enough studies on this pattern that it has a name: transfer penalty. The transfer penalty consists of three elements:
- Walking time between platforms or bus curbs
- Waiting time for the connecting train or bus
- An independent inconvenience factor in addition to the extra time
One meta-study of this topic is by Iseki-Taylor-Miller of the Institute for Transportation Studies. There’s a bewildering array of different assumptions and even in the same city the estimates may differ. The usual way this is planned in elasticity estimates is to bundle the inconvenience factor into walking and waiting times; passengers perceive these to be more onerous than in-vehicle time, by a factor that depends on the study. Iseki-Taylor-Miller quote a factor as low as 1.4-1.7 and Lago-Mayworm-McEnroe’s classic paper, sourced to a Swedish study, go up to 3; Teulings-Ossokina-de Groot suggest it is 2, which is the figure I usually use, because of the convenience of assuming worst-case scenario for waiting time (on average, the wait is half the headway).
The penalty differs based on the quality of station facilities, and Fan-Guthrie-Levinson investigate this for bus shelter. However, urban rail estimates including those in the above meta-studies are less dependent on station facilities, which are good in all cases.
Mitigating the transfer penalty
Reducing the transfer penalty for riders can be done in three ways, if one believes the model with a constant penalty factor (say 2):
- Reducing the number of transfers
- Reducing walking time between platforms
- Reducing waiting time for trains
All three are useful strategies for good urban rail network planning, and yet all three are useful only up to a point, beyond which they create more problems than they solve.
The most coherent network planning principle for reducing passengers’ need to transfer is to build radial rail networks. Such networks ideally ensure each pair of lines intersects once in or near city center, with a transfer, and thus there is at most one transfer between any pair of stations. A circumferential line may be added, creating some situations in which a three-legged trip is superior in case it saves a lot of time compared with the two-legged option; in Moscow, the explicit purpose of the Circle Line is to take pressure off the congested passageway of the central transfer connecting the first three lines.
In general, the most coherent radial networks are those inherited from the Soviet tradition of metro building; the London Underground, which influenced this tradition in the 1920s, is fairly radial itself, but has some seams. It’s important in all cases to plan forward and ensure that every pair of lines that meets has a transfer. New York has tens of missed connections on the subway, and Tokyo has many as well, some due to haphazard planning, some due to an explicit desire to build the newer lines as express relief lines to the oversubscribed older lines.
On a regional rail network, the planning is more constrained by the need to build short tunnels connecting existing lines. In that case, it’s best to produce something as close to a coherent radial network with transfers at all junctions as possible. Through-running is valuable here, even if most pairs of origins and destinations on a branched commuter line trunk still require a transfer, for two reasons. First, if there is through-running, then passengers can transfer at multiple points along the line, and not just at the congested city center terminus. And second, while through-running doesn’t always cut the transfer for suburb-to-suburb trips, it does reliably cut the transfer for neighborhood-to-suburb trips involving a connection to the metro: a diameter can be guaranteed to connect with all radial metro lines, whereas a radius (terminating at city center) will necessarily miss some of them, forcing an extra transfer on many riders.
Reducing walking time
The ideal transfer is cross-platform, without any walking time save that necessary to cross a platform no more than 10-15 meters wide. Some metro building traditions aim for this from the outset: London has spent considerable effort on ensuring the key Victoria line transfers are cross-platform and this has influenced Singapore and Hong Kong, and Berlin has accreted several such transfers, including between the U- and S-Bahn at Wuhletal.
However, this is not always viable. The place where transfers are most valuable – city center – is also where construction is the most constrained. If two lines running under wide streets cross, it’s usually too costly to tilt them in such a way that the platforms are parallel and a cross-platform transfer is possible. But even in that case, it’s best to make the passageways between the platforms as short as possible. A cruciform configuration with stairs and an elevator in the middle is the optimum; the labyrinthine passageways of Parisian Métro stations are to be avoided.
Reducing waiting time
The simplest way to reduce waiting time is to run frequently. Passengers’ willingness to make untimed transfers is the highest when frequency is the highest, because the 2-minute wait found on such systems barely lengthens one’s trip even in the worst case, when one has frustratingly just missed the train.
Radial metro networks based on two- rather than one-seat rides pair well with high frequency. Blog supporter and frequent commenter Threestationsquare went viral last month when he visited Kyiv, a Soviet-style three-line radial system, and noted that due to wartime cuts the trains only run every 6-7 minutes off-peak; Americans amplified this and laughed at the idea that base frequency could be so high that a train every 7 minutes takes the appellation “only.”
When frequency is lower, for example on a branch or at night, cross-platform transfers can be timed, as is the case in Berlin. But these are usually accidental transfers, since the core city center transfers are on frequent trunks, and thus the system is only valuable at night. Moreover, timed transfers almost never work outside cross-platform transfers, which as noted above are not always possible; the only example I’m aware of is in Vienna, where a four-way transfer with stacked parallel platforms is timed.
This is naturally harder on a branched commuter rail system. In that case, it’s possible to set up the timetable to make the likeliest origin-destination pairs have short transfer windows, or even one-seat rides. However, in general transfers may require a wait as long as the system’s base clockface intervals, which is unlikely to be better than 20 minutes except on the busiest trunks in the largest cities; even Paris mixes 10-, 15-, and occasionally 20- and 30-minute intervals on RER branches.
Two years ago I wrote about how New York should aim to run every bus and subway service every six minutes off-peak. Buses would require a combination of aggressive bus redesign and speedup treatments for this to be viable. The subway already has very low variable operating costs off-peak and such a boost in frequency would naturally increase efficiency; New York City Transit gets around 550 service-hours annually per train driver, whereas the Berlin U-Bahn with its flat all-day schedule gets around 900. But now, the more mainstream New York-area transit advocacy group Riders’ Alliance has its own proposal for six-minute service, which it has aggressive marketed using the hashtag #6minuteservice.
This is a good campaign and I hope more people in the region take notice and push for it until the state implements it in full. The impact on passenger convenience is massive, not just in the form of shorter waits but also higher reliability coming from better timetabling, and hopefully also slightly more speed coming from said higher reliability. The proposal says that it would take $250 million a year in extra spending to effect this system, and it’s unknown but plausible that it would increase ridership by enough to defray this cost entirely, even without any efficiency treatments to reduce unit costs.
What’s in the Riders’ Alliance proposal?
Between 5 am and 9 pm on weekdays, and between 8 am and 10 pm on weekends, all subway routes and the top 100 bus routes in the city should run at worst every six minutes. This echoes a report by the comptroller’s office from last year, recommending this as an alternative to rush hour-focused service by bringing up corona-related ridership decreases.
It’s not stated but I think the subway routes in question are reckoned by letter or number, which means the A train runs every six minutes but each of its two branches runs every 12. This is fine – the two branches of the A are exceptionally far out, which is why a single service splits to them, where elsewhere in New York each branch gets its own number or letter.
The implications for timetabling
Timetabling a consistent all-day service is much easier than timetabling bespoke service patterns. The Riders’ Alliance proposal aims to face the general public rather than planners and therefore omits this benefit, but this benefit reaches passengers as well, in non-obvious ways.
First, if all trains and buses run every six minutes, then it’s possible to set up clockface timetables. These don’t matter very much if they run every six minutes, but they do if they run every 12, as I expect the two A branches to. The same is true of buses that branch: some outer ends may run every 12 minutes, in which case they can and should run on repeating clockface timetables that passengers can memorize. Passengers who can remember “my bus leaves at :01, :13, :25, :37, and :49” without having to consult timetables or trip planners all the time are likelier to take the trip; this was my commute for a year in Vancouver.
The A train today runs every 15 minutes on each branch but it’s not on a consistent clockface schedule, which depresses ridership. In effect, current practice is little different from what Swiss planners warn of: they say the best way to reduce ridership is to run service every 11, 13, or 17 minutes, rather than every 12 or 15 on a clockface pattern.
Second, if all trains run on the same frequency, then service planning on a complexly interlined system like New York’s becomes more tractable. Today, every train runs on a separate frequency, often different from the services it shares track with. The 2 and 3 trains share track most of the way, from Franklin Avenue to 135th Street, but the 2 is just a little more frequent, resulting in the following northbound timetable at Franklin:
This is irregular both on the trunk and on each individual service – the 2 on average runs every eight minutes but has a 12-minute gap, and the 3 runs on average every nine but also has a 12-minute gap. It’s an unavoidable consequence of the combination of extensive reverse-branching and subway frequency guidelines that run different services at different headways. The six-minute service proposal straightens this by aligning the trains to a single frequency, with regular alternation between successive trains on trunks.
And third, another benefit of a regular frequency to planning is that schedule planners can reliably avoid merge conflicts. This, in turn, speeds up service, which is full of planned delays and schedule padding at pain points. It’s not a full substitute for deinterlining, which would eliminate the merge conflicts at the worst junctions, but it makes it viable to no longer write impossible schedules with the planning department that New York City Transit has.
Service quality and demographics
Both Riders’ Alliance and the comptroller report it uses as its source point out demographic differences between peak and off-peak riders: rush hour subway commuters have a median income of $50,783 a year, even higher (slightly) than drivers, but off-peak subway commuters have a median income of $37,048 and bus commuters have a median income of $30,374.
In both reports this is taken to be indicative that off-peak service is mostly for poorer people, but it’s not the right analysis. The picture that emerges from the data is not that in general rush hour commuters outearn off-peak commuters; for one, most off-peak commutes are done by car, not by public transportation. Rather, what’s going on is that off-peak public transit quality is bad and this suppresses ridership among those who can afford a car.
By the same token, we can look at the incomes of commuters in regions of the United States that have no public transit to speak of – maybe some buses or even a few trains but with rounding-error ridership and low single-digit modal split. In metro New York, public transit and car commuters have about the same median income, and in some secondary transit cities like Chicago public transit commuters actually outearn drivers, since service to non-CBD destinations is so bad it suppresses ridership below median income more than above it. But in places like Los Angeles, the median income of transit commuters is not much more than half that of car commuters, because service quality is so bad that anyone who can afford to drive does.
The upshot of this is that better off-peak transit service is going to increase the average income of off-peak transit users, by attracting people who currently drive. This is also going to lead to higher-socioeconomic status shifts: higher levels of degree attainment, a larger proportion of white riders, a larger proportion of native-born riders.
I bring this up because a rise in the relative average income of users as service quality improves means the improvement is working as intended. It doesn’t mean the subway is gentrifying or turns away poorer riders, it just means it no longer repels riders who can afford to drive. This is important, because too much American transit planning is based on market segmentation in which service is supposed to be for a specific class of rider, and if the demographics are changing it means it’s being revamped for a different class. In reality, there’s just one transit system for one city and income differences are indicative of quality differences and not of inherent differences in the travel market.
How much does this cost? What is the ridership impact?
The Riders’ Alliance proposal says the additional cost of the program is $250 million a year in operating expenses. In 2019, NYCT spent $8.8 billion on operations and got $4.6 billion in fares, so this is in theory a 6% increase in subsidy, and in practice a little less as better service attracts more fare-paying riders. This is without any concurrent attempts to use the increase in service to increase efficiency (read: reduce unit staffing levels) and, I think, without bus speedups that permit much higher frequency for the same cost.
It’s unclear what the revenue impact should be; the ridership impact can be estimated from longstanding results in the literature about ridership-frequency elasticity, which in the case of NYCT should be about 0.4. The proposal increases off-peak service on the subway by around 50% in principle and a bit more in practice because of the reduced variability in frequency, say two-thirds: most lines are to go from 10- to six-minute headways and the rest, which are mostly more frequent than this, get a smaller increase that we round up to two-thirds by taking the impact of higher reliability into account. This means an increase in off-peak ridership of around 23%. The bus impact is even larger – in Brooklyn the median bus headway is right between 12 and 15 minutes, and even taking into account that the busiest buses do much better, this is close to a doubling of the effective frequency.
In turn, most ridership is off-peak. In 2019, peak (7-10 am) ridership into the Manhattan core was 923,000 per weekday, amounting to 44% of ridership entering the Manhattan core on a weekday, or around 33% of all inbound weekday ridership and 27% of all ridership. Even adding a bit to account for peak ridership that doesn’t enter Manhattan, only about a third of subway ridership in New York was at the peak before corona; the peak share has fallen since, but is slowly creeping back up as workers slowly return to the office. Raising two-thirds of ridership by 23% is massive – it’s a 15% systemwide increase for a much smaller increase in operating costs, and a somewhat larger increase in bus ridership to boot.
Unfortunately, I can’t turn this into a revenue impact estimate. While the demographics in the section above specify off-peak commuters, the studies that my ridership estimate is based on measure riders, including peak commuters who ride more often for non-work trips. Such riders already have monthly passes, so making it easier for them to ride is excellent for the city’s long-term health but doesn’t defray the added cost. Converted riders who are not already on the system as well as the odd peak rider who doesn’t already have a pass do generate more revenue, but I don’t know how many there are; these need to be a little more than a third of the overall increase in ridership to fully defray costs, which sounds plausible to me.
Eno has a new report out about mass transit project delivery, which I encourage everyone to read. It compares the American situation with 10 other countries: Canada, Mexico, Chile, Norway, Germany, Italy, South Africa, Japan, South Korea, and Australia. Project head Paul Lewis just gave a webinar about this, alongside Phil Plotch. Eno looks at high-level governance issues, trying to figure out if there’s some correlation with factors like federalism, the electoral system, and the legal system; there aren’t any. Instead of those, they try teasing out project delivery questions like the role of consultants, the contracting structure, and the concept of learning from other people.
This is an insightful report, especially on the matter of contract sizing, which they’ve learned from Chile. But it has a few other gems worth noting, regarding in-house planning capacity and, at meta level, learning from other people.
How Eno differs from us
The Transit Costs Project is a deep dive into five case studies: Boston, New York, Stockholm (and to a lesser extent other Nordic examples), Istanbul (and to a lesser extent other Turkish examples), and the cities of Italy. This does not mean we know everything there is to know about these cases; for example, I can’t speak to the issues of environmental review in the Nordic countries, since they never came up in interviews or in correspondence with people discussing the issue of the cost escalation of Nya Tunnelbanan. But it does mean knowing a lot about the particular history of particular projects.
Eno instead studies more cases in less detail. This leads to insights about places that we’ve overlooked – see below about Chile and South Korea. But it also leads to some misinterpretations of the data.
The most significant is the situation in Germany. Eno notes that Germany has very high subway construction costs but fairly low light rail costs. The explanation for the latter is that German light rail is at-grade trams, the easiest form of what counts as light rail in their database to build. American light rail construction costs are much higher partly because American costs are generally very high but also partly because US light rail tends to be more metro-like, for example the Green Line Extension in Boston.
However, in the video they were asked about why German subway costs were high and couldn’t answer. This is something that I can answer: it’s an artifact of which subway projects Germany builds. Germany tunnels so little, due to a combination of austerity (money here goes to gas subsidies, not metro investments) and urbanist preference for trams over metros, that the tunnels that are built are disproportionately the most difficult ones, where the capacity issues are the worst. The subways under discussion mostly include the U5 extension in Berlin, U4 in Hamburg, the Kombilösung in Karlsruhe, and the slow expansion of the tunneled part of the Cologne Stadtbahn. These are all city center subways, and even some of the outer extensions, like the ongoing extension of U3 in Nuremberg, are relatively close-in. The cost estimates for proposed outer extensions like U7 at both ends in Berlin or the perennially delayed U8 to Märkisches Viertel are lower, and not too different per kilometer from French levels.
This sounds like a criticism, because it mostly is. But as we’ll see below, even if they missed the ongoing changes in Nordic project delivery, what they’ve found from elsewhere points to the exact same conclusions regarding the problems of what our Sweden report calls the globalized system, and it’s interesting to see it from another perspective; it deepens our understanding of what good cost-effective practices for infrastructure are.
The issue of contract sizing in the Transit Costs Project
Part of what we call the globalized system is a preference for fewer, larger contracts over more, smaller ones. Trafikverket’s procurement strategy backs this as a way of attracting international bidders, and thus the Västlänken in Gothenburg, budgeted at 20,000 kronor in 2009 prices or around $2.8 billion in 2022 prices, comprises just six contracts. A planner in Manila, which extensively uses international contractors from all over Asia to build its metro system (which has reasonable elevated and extremely high underground costs), likewise told us that the preference for larger contracts is good, and suggested that Singapore may have high costs because it uses smaller contracts.
While our work on Sweden suggests that the globalized system is not good, the worst of it appeared to us to be about risk allocation. The aspects of the globalized system that center private-sector innovation and offload the risk to the contractor are where we see defensive design and high costs, while the state reacts by making up new regulations that raise costs and achieve little. But nothing that we saw suggested contract sizing was a problem.
And in comes Eno and brings up why smaller contracts are preferable. In Chile, where Eno appears to have done the most fieldwork, metro projects are chopped into many small contracts, and no contractor is allowed to get two adjacent segments. The economic logic for this is the opposite of Sweden’s: Santiago wishes to make its procurement open to smaller domestic firms, which are not capable of handling contracts as large as those of Västlänken.
And with this system, Santiago has lower costs than any Nordic capital. Project 63, building Metro Lines 3 and 6 at the same time, cost in 2022 PPP dollars $170 million/km; Nya Tunnelbanan is $230 million/km if costs don’t run over further, and the other Nordic subways are somewhat more expensive.
Other issues of state capacity
Eno doesn’t use the broader political term state capacity, but constantly alludes to it. The report stresses that project delivery must maintain large in-house planning capacity. Even if consultants are used, there must be in-house capacity to supervise them and make reasonable requests; clients that lack the ability to do anything themselves end up mismanaging consultants and making ridiculous demands, which point comes out repeatedly and spontaneously for our sources as well as those of Eno. While Trafikverket aims to privatize the state on the British model, it tries to retain some in-house capacity, for example picking some rail segments to maintain in-house to benchmark private contractors against; at least so far, construction costs in Stockholm are around two-fifths those of the Battersea extension in London, and one tenth those of Second Avenue Subway Phase 1.
With their broader outlook, Eno constantly stresses the need to devolve planning decisions to expert civil servants; Santiago Metro is run by a career engineer, in line with the norms in the Spanish- and Portuguese-language world that engineering is a difficult and prestigious career. American- and Canadian-style politicization of planning turns infrastructure into a black hole of money – once the purpose of a project is spending money, it’s easy to waste any budget.
Finally, Eno stresses the need to learn from others. The example it gives is from Korea, which learned the Japanese way of building subways, and has perfected it; this is something that I’ve noticed for years in my long-delayed series on how various countries build, but just at the level of a diachronic metro map it’s possible to see how Tokyo influenced Seoul. They don’t say so, but Ecuador, another low-cost Latin American country, used Madrid Metro as consultant for the Quito Metro.
I made a four-hour video about New York commuter rail timetabling on Tuesday (I stream on Twitch most Tuesdays at 19:00 Berlin time); for this post, I’d like to extract just one piece of this, which informs how I do commuter rail proposals versus how Americans do them. For lack of a better term, on video I called one of the American planning maxims that I violate the baboon rule. The baboon rule states that an agency must assume that other agencies that it needs to interface with are run by baboons, who are both stupid and unmovable. This applies to commuter rail schedule planning but also to infrastructure construction, which topic I don’t cover in the video.
How coordination works
Coordination is a vital principle of good infrastructure planning. This means that multiple users of the same infrastructure, such as different operators running on the same rail tracks, or different utilities on city streets, need to communicate their needs and establish long-term horizontal relationships (between different users) and vertical ones (between the users and regulatory or coordinating bodies).
In rail planning this is the Verkehrsverbund, which coordinates fares primarily but also timetables. There are timed transfers between the U- and S-Bahn in Berlin even though they have two different operators and complex networks with many nodes. In Zurich, not only are bus-rail transfers in the suburbs timed on a 30-minute Takt, but also buses often connect two distinct S-Bahn lines, with timed connections at both ends, with all that this implies about how the rail timetables must be built.
But even in urban infrastructure, something like this is necessary. The same street carries electric lines, water mains, sewer mains, and subway tunnels. These utilities need to coordinate. In Milan, Metropolitana Milanese gets to coordinate all such infrastructure; more commonly, the relationships between the different utilities are horizontal. This is necessary because the only affordable way to build urban subways is with cut-and-cover stations, and those require some utility relocation, which means some communication between the subway builders and the utility providers is unavoidable.
The baboon rule
The baboon rule eschews coordination. The idea, either implicit or explicit, is that it’s not really possible to coordinate with those other agencies, because they are always unreasonable and have no interest in resolving the speaker’s problems. Commuter rail operators in the Northeastern US hate Amtrak and have a litany of complaints about its dispatching, and vice versa – and as far as I can tell those complaints are largely correct.
Likewise, subway builders in the US, and not just New York, prefer deep tunneling at high costs and avoid cut-and-cover stations just to avoid dealing with utilities. This is not because American utilities are unusually complex – New York is an old industrial city but San Jose, where I’ve heard the same justification for avoiding cut-and-cover stations, is not. The utilities are unusually secretive about where their lines are located, but that’s part of general American (or pan-Anglosphere) culture of pointless government secrecy.
I call this the baboon rule partly because I came up with it on the fly during a Twitch stream, and I’m a lot less guarded there than I am in writing. But that expression came to mind because of the sheer horror that important people at some agencies exuded when talking about coordination. Those other agencies must be completely banally evil – dispatching trains without regard for systemwide reliability, or demanding their own supervisors have veto power over plans, or (for utilities) demanding their own supervisors be present in all tunneling projects touching their turf. And this isn’t the mastermind kind of evil, but rather the stupid kind – none of the complaints I’ve heard suggests those agencies get anything out of this.
The baboon rule and coordination
The commonality to both cases – that of rail planning and that of utility relocation – is the pervasive belief that the baboons are unmovable. Commuter rail planners ask to be separated from Amtrak and vice versa, on the theory that the other side will never get better. Likewise, subway builders assume electric and water utilities will always be intransigent and there’s nothing to be done about it except carve a separate turf.
And this is where they lose me. These agencies largely answer to the same political authority. All Northeastern commuter rail agencies are wards of the federal government; in Boston, the idea that they could ever modernize commuter rail without extensive federal funding is treated as unthinkable, to the point that both petty government officials and advocates try to guess what political appointees want and trying to pitch plans based on that (they never directly ask, as far as I can tell – one does not communicate with baboons). Amtrak is of course a purely federal creature. A coordinating body is fully possible.
Instead, the attempts at coordination, like NEC Future, ask each agency what it wants. Every agency answers the same: the other agencies are baboons, get them out of our way. This way the plan has been written without any meaningful coordination, by a body that absolutely can figure out combined schedules and a coordinated rolling stock purchase programs that works for everyone’s core passenger needs (speed, capacity, reliability, etc.).
The issue of utilities is not too different. The water mains in New York are run by DEP, which is a city agency whereas the MTA is a state agency – but city politicians constantly proclaim their desire to improve city infrastructure, contribute to MTA finances and plans (and the 7 extension was entirely city-funded), and would gain political capital from taking a role in facilitating subway construction. And yet, it’s not possible to figure out where the water mains are, the agency is so secretive. Electricity and steam are run by privately-owned Con Ed, but Con Ed is tightly regulated and the state could play a more active role in coordinating where all the underground infrastructure is.
And yet, in no case do the agencies even ask for such coordination. No: they ask for turf separation. They call everyone else baboons, if not by that literal term, but make the same demands as the agencies that they fight turf wars with.
Advocates for mass transit often have to confront the issue of competing priorities for investment. These include some long-term tensions: maintenance versus expansion, bus versus rail, tram versus subway and commuter rail, high-speed rail versus upgraded legacy rail, electronics versus concrete. In some cases, they genuinely compete in the sense that building one side of the debate makes the other side weaker. But in others, they don’t, and instead they reinforce each other: once one investment is done, the one that is said to compete with it becomes stronger through network effects.
Urban rail capacity
Capacity is an example of when priorities genuinely compete. If your trains are at capacity, then different ways to relieve crowding are in competition: once the worst crowding is relieved, capacity is no longer a pressing concern.
This competition can include different relief lines. Big cities often have different lines that can be used to provide service to a particular area, and smaller ones that have to build a new line can have different plausible alignments for it. If one line is built or extended, the case for parallel ones weakens; only the strongest travel markets can justify multiple parallel lines.
But it can also include the conflict between building relief lines and providing extra capacity by other means, such as better signaling. The combination of conventional fixed block signaling and conventional operations is capable of moving maybe 24 trains per hour at the peak, and some systems struggle even with less – Berlin moves 18 trains per hour on the Stadtbahn, and has to turn additional peak trains at Ostbahnhof and make passengers going toward city center transfer. Even more modern signals struggle in combination with too complex branching, as in New York and some London lines, capping throughput at the same 24 trains per hour. In contrast, top-of-line driverless train signaling on captive metro lines can squeeze 42 trains per hour in Paris; with drivers, the highest I know of is 39 in Moscow, 38 on M13 in Paris, and 36 in London. Put another way, near-best-practice signaling and operations are equivalent in capacity gain to building half a line for every existing line.
Reach and convenience
In contrast with questions of capacity, questions of system convenience, accessibility, reliability, and reach show complementarity rather than competition. A rail network that is faster, more reliable, more comfortable to ride, and easier to access will attract more riders – and this generates demand for extensions, because potential passengers would be likelier to ride in such case.
In that sense, systematic improvements in signaling, network design, and accessibility do not compete with physical system expansion in the long run. A subway system with an elevator at every station, platform edge doors, and modern (ideally driverless) signaling enabling reliable operations and high average speeds is one that people want to ride. The biggest drawback of such a system is that it doesn’t go everywhere, and therefore, expansion is valuable. Expansion is even more valuable if it’s done in multiple directions – just as two parallel lines compete, lines that cross (such as a radial and a circumferential) reinforce each other through network effects.
This is equally true of buses. Interventions like bus shelter interact negatively with higher frequency (if there’s bus shelter, then the impact of wait times on ridership is reduced), but interact positively with everything else by encouraging more people to ride the bus.
The interaction between bus and rail investments is positive as well, not negative. Buses and trains don’t really compete anywhere with even quarter-decent urban rail. Instead, in such cities, buses feed trains. Bus shelter means passengers are likelier to want to ride the bus to connect the train, and this increases the effective radius of a train station, making the case for rail extensions stronger. The same is true of other operating treatments for buses, such as bus lanes and all-door boarding – bus lanes can’t make the bus fast enough to replace the subway, but do make it fast enough to extend the subway’s range.
Mainline rail investments
The biggest question in mainline rail is whether to build high-speed lines connecting the largest cities on the French or Japanese model, or to invest in more medium-speed lines to smaller cities on the German or especially Swiss model. German rail advocates assert the superiority of Germany to France as a reason why high-speed rail would detract from investments in everywhere-to-everywhere rail transport.
But in fact, those two kinds of investment complement each other. The TGV network connects most secondary cities to Paris, and this makes regional rail investments feeding those train stations stronger – passengers have more places to get to, through network effects. Conversely, if there is a regional rail network connecting smaller cities to bigger ones, then speeding up the core links gives people in those smaller cities more places to get to within two, three, four, five hours.
This is also seen when it comes to reliability. When trains of different speed classes can use different sets of track, it’s less likely that fast trains will get stuck behind slow ones, improving reliability; already Germany has to pad the intercity lines 20-25% (France: 10-14%; Switzerland: 7%). A system of passenger-dedicated lines connecting the largest cities is not in conflict with investments in systemwide reliability, but rather reinforces such reliability by removing some of the worst timetable conflicts on a typical intercity rail system in which single-speed class trains never run so often as to saturate a line.
Recommendation: invest against type
The implication of complementarity between some investment types is that a system that has prioritized one kind of investment should give complements a serious look.
For example, Berlin has barely expanded the U-Bahn in the last 30 years, but has built orbital tramways, optimized timed connections (for example, at Wittenbergplatz), and installed elevators at nearly all stations. All of these investments are good and also make the case for U-Bahn expansion stronger to places like Märkisches Viertel and Tegel.
In intercity rail, Germany has invested in medium-speed and regional rail everywhere but built little high-speed rail, while France has done the opposite. Those two countries should swap planners, figuratively and perhaps even literally. Germany should complete its network of 300 km/h lines to enable all-high-speed trips between the major cities, while France should set up frequent clockface timetables on regional trains anchored by timed connections to the TGV.
I was asked by an area advocate about SkyTrain, and this turned into a long email with various models to compare Vancouver with. In my schema contrasting suburban metro systems and S-Bahns, Vancouver is firmly in the first category: SkyTrain is not commuter rail, and Vancouver’s commuter rail system, the West Coast Express, is so weak it might as well not exist. The suburban metro model forces the region to engage in extensive transit-oriented development, which Vancouver has done. Has it been successful? To some extent, yes – Vancouver’s modal split is steadily rising, and in the 2016 census, just before the Evergreen Line opened, was 20%; supposedly it is 24% now. But it could have done better. How so?
Could Vancouver have used the S-Bahn model?
There is a common line of advocacy; glimpses of it can be found on the blog Rail for the Valley, by a writer using the name Zweisystem who commented on transit blogs like Yonah and Jarrett‘s in the 2000s. Using the name of Karlsruhe’s tram-train as inspiration, Zwei has proposed that Vancouver use existing commuter rail corridors in suburban and exurban areas and streetcars in the urban core.
The problem with this is that Vancouver has very little legacy mainline rail infrastructure to work with. There are two mainlines serving city center: the Canadian Pacific, and Canadian National. The CP line hugs the coast, full of industrial customers; the CN line is farther inland and has somewhat more fixable land use, but the Millennium Line partly parallels it and even after 20 years its ridership is not the strongest in the system. Most of the urban core is nowhere near a rail mainline.
This is completely unlike the Central European S-Bahn-and-streetcars systems, all of which have legacy commuter lines radiating in all directions, and use legacy streetcars rather than newly-built light rail lines. In the last generation they’ve expanded their systems, building connections and feeding rapid transit, but none of these is a case of completely getting rid of the streetcars and then restoring them later; the busiest system that’s entirely new, that of Paris, is largely orbitals and feeders for the Métro and RER.
Vancouver did in fact reuse old infrastructure for the suburban metro concept. The Expo Line involved very little greenfield right-of-way use. Most of the core route between the historic core of Vancouver and New Westminster is in the private right-of-way of a historic BC Electric interurban; this is why it parallels Kingsway but does not run elevated over it. The tunnel in Downtown Vancouver is a disused CP tunnel; this is why the tracks are stacked one over the other rather than running side by side – the tunnel was single-track but tall enough to be cut into two levels. This limited the construction cost of the Expo Line, which the largely-elevated Millennium Line and the partly underground, partly elevated Canada Line could not match.
The Stockholm example
In my post about S-Bahns and suburban metros, I characterized Stockholm as an archetypal suburban metro. Stockholm does have an S-Bahn tunnel nowadays, but it only opened 2017, and ridership so far, while rising, is still a fraction of that of the T-bana.
Stockholm’s choice of a full metro system in the 1940s, when it had about a million people in its metro area, had its critics at the time. But there wasn’t much of a choice. The trams were fighting growing traffic congestion, to the point that some lines had to be put in a tunnel, which would later be converted for the use of the Green Line as it goes through Södermalm. Working-class housing was overcrowded and there was demand for more housing in Stockholm, which would eventually be satisfied by the Million Program.
And there were too few commuter lines for an S-Bahn system. Swedes were perfectly aware of the existence of the S-Bahn model; Berlin and Hamburg both had S-Bahns running on dedicated tracks, and Copenhagen had built its own system, called S-Tog in imitation of the German name. But they didn’t build that. None of this was the integrated Takt timetable that Munich would perfect in the 1970s, in which branches could be left single-track or shared with intercity trains provided the regular 20-minute headways could be scheduled to avoid conflicts; the track sharing required in the 1940s would have been too disruptive. Not to mention, Stockholm had too few lines, if not so few as Vancouver – only two branches on each of two sides of city center, with most of the urban core far from the train.
So Stockholm built the T-bana, with three highly branched lines all meeting at T-Centralen, the oldest two of the three having a cross-platform transfer there and at the two stations farther south. The roughly 104 km system (57 km underground) cost, in 2022 US dollars, $3.6 billion. Stockholm removed all the regular streetcars; a handful running all or mostly in private rights-of-way were retained with forced transfers at outlying T-bana stations like Ropsten, as was the narrow-gauge Roslagsbana (with a forced transfer at KTH, where I worked for two years).
At the same time the T-bana was under construction, the state built the Million Program, and in the Stockholm region, the housing projects were designed to be thoroughly oriented around the system. The pre-Million Program TOD suburb of Vällingby was envisioned as part of a so-called string of pearls, in which towns would radiate from each T-bana station, with local retail and jobs near the station surrounded by housing. In 2019, the T-bana had 1,265,900 riders per workday, Citybanan had 410,300, and the remaining lines 216,100; Sweden reports modal split for all trips and not just work trips, but the commute modal split appears to be 40% or a little higher, a figure that matches Paris, a metro area of 13 million that opened its first metro line in 1900.
So why is Stockholm better?
There are parallels between Stockholm and Vancouver – both are postwar cities with 2.5 million people in their metropolitan areas with rapid growth due to immigration. Their physical geographies are similar, with water barriers inhibiting the contiguous sprawl of many peers. Both extensively employed TOD to shape urban geography around the train: Stockholm has Vällingby and other, less famous examples of TOD; Vancouver has Metrotown and smaller examples of residential TOD along the Expo Line, alongside a famously high-rise downtown. But the T-bana has more than twice the annual ridership of SkyTrain, and Stockholm has around twice the modal split of Vancouver – this is not a matter of Canadians riding buses more than Europeans do. So what gives?
Part of it is about TOD models. Stockholm is an exceptionally monocentric city, and this has created a lot of demand for urban rail to Central Stockholm. But Vancouver’s high-rise city center has a lot of jobs, and overall, around 30% of Metro Vancouver jobs are in the city or the University Endowment Lands (that is, UBC), and the proportion of Stockholm County jobs within an equivalent area is similar. Vancouver has never built anything as massive as the Million Program, but its housing growth rate is one of the highest in the world (around 11 gross units/1,000 people per year in the 2010s), and much of that growth clusters near the Expo Line and increasingly also near the worse-developed Millennium and Canada Lines.
I suspect that the largest reason is simply the extent of the systems. SkyTrain misses the entire West Side of Vancouver west of Cambie, has poor coverage in Surrey and none in Langley, and does not cross the Burrard Inlet. The T-bana has no comparable lacunae: Roslag is served by Roslagsbanan, and the areas to be served by the under-construction extensions are all target TOD areas with much less present-day density than North Vancouver, the cores of Fairview and Kitsilano, or the town centers in Surrey other than Whalley.
What’s more, Stockholm’s construction costs may be rising but those of Vancouver (and the rest of Canada) are rising even faster and from a higher base. Nya Tunnelbanan is currently budgeted at $3.6 billion in PPP terms – 19 underground km for about the same cost as the existing 104 – but Vancouver is building half of the most critical SkyTrain extension, that under Broadway, for C$2.83 billion (US$2.253 billion in PPP terms) for just 5 km, not all underground. The projected cost per rider is still favorable, but it’s less favorable for the planned extension to Langley, and there’s no active plan for anything to the North Shore.
The silver lining for Vancouver is that the West Side is big and underdeveloped. The region has the money to extend SkyTrain not just to Arbutus as is under construction but all the way to UBC, and the entire swath of land between Central Broadway and UBC screams “redevelop me.” The current land use is a mix of mid-rise, townhouses (“missing middle”), and single-family housing; Shaughnessy, whose northern end is within a kilometer of under-construction SkyTrain stations, is single-family on large lots, and can be redeveloped as high-rise housing alongside closer-in areas. Canada does not have Europe’s allergy to tall buildings, and this is a resource that can be used to turn Vancouver into a far more transit-oriented city along the few corridors where it can afford to build. The suburban metro is always like this: fewer lines, more development intensity along them.
A brief discussion on Reddit about my post criticizing Penn Station expansion plans led me to write a very long comment, which I’d like to hoist to a full post explaining how big an urban train station needs to be to serve regional and intercity rail traffic. The main principles are,
- Good operations can substitute for station size, and it’s always cheaper to get the system to be more reliable than to build more tracks in city center.
- Through-running reduces the required station footprint, and this is one of the reasons it is popular for urban commuter rail systems.
- The simpler and more local the system is, the fewer tracks are needed: an urban commuter rail system running on captive tracks with no sharing tracks with other traffic and with limited branching an get away with smaller stations than an intercity rail station featuring trains from hundreds of kilometers away in any direction.
The formula for minimum headways
On subways, where usually the rush hour crunches are the worst, trains in large cities run extremely frequently, brushing up against the physical limitation of the tracks. The limit is dictated by the brick wall rule, which states that the signal system must at any point assume that the train ahead can turn into a brick wall and stop moving and the current train must be able to brake in time before it reaches it. Cars, for that matter, follow the same rule, but their emergency braking rate is much faster, so on a freeway they can follow two seconds apart. A metro train in theory could do the same with headways of 15 seconds, but in practice there are stations on the tracks and dealing with them requires a different formula.
With metro-style stations, without extra tracks, the governing formula is,
Platform clearing time is how long it takes the train to clear its own length; the idea of the formula is that per the brick wall rule, the train we’re on needs to begin braking to enter the next station only after the train ahead of ours has cleared the station.
But all of this is in theory. In practice, there are uncertainties. The uncertainties are almost never in the stopping or platform clearing time, and even the dwell time is controllable. Rather, the schedule itself is uncertain: our train can be a minute late, which for our purpose as passengers may be unimportant, but for the scheduler and dispatcher on a congested line means that all the trains behind ours have to also be delayed by a minute.
What this means that more space is required between train slots to make schedules recoverable. Moreover, the more complex the line’s operations are, the more space is needed. On a metro train running on captive tracks, if all trains are delayed by a minute, it’s really not a big deal even to the control tower; all the trains substitute for one another, so the recovery can be done at the terminal. On a mainline train running on a national network in which our segment can host trains to Budapest, Vienna, Prague, Leipzig, Munich, Zurich, Stuttgart, Frankfurt, and Paris, trains cannot substitute for one another – and, moreover, a train can be easily delayed 15 minutes and need a later slot. Empty-looking space in the track timetable is unavoidable – if the schedule can’t survive contact with the passengers, it’s not a schedule but crayon.
How to improve operations
In one word: reliability.
In two words: more reliability.
Because the main limit to rail frequency on congested track comes from the variation in the schedule, the best way to increase capacity is to reduce the variation in the schedule. This, in turn, has two aspects: reducing the likelihood of a delay, and reducing the ability of a delay to propagate.
The central insight about delays is that they may occur anywhere on the line, roughly in proportion to either trip time or ridership. This means that on a branched mainline railway network, delays almost never originate at the city center train station or its approaches, not because that part of the system is uniquely reliable, but because the train might spend five minutes there out of a one-hour trip. The upshot is that to make a congested central segment more reliable, it is necessary to invest in reliability on the entire network, most of which consists of branch segments that by themselves do not have capacity crunches.
The biggest required investments for this are electrification and level boarding. Both have many benefits other than schedule reliability, and are underrated in Europe and even more underrated in the United States.
Electrification is the subject of a TransitMatters report from last year. As far as reliability is concerned, the LIRR and Metro-North’s diesel locomotives average about 20 times the mechanical failure rate of electric multiple units (source, PDF-pp. 36 and 151). It is bad enough that Germany is keeping some outer regional rail branches in the exurbs of Berlin and Munich unwired; that New York has not fully electrified is unconscionable.
Level boarding is comparable in its importance. It not only reduces dwell time, but also reduces variability in dwell time. With about a meter of vertical gap between platform and train floor, Mansfield has four-minute rush hour dwell times; this is the busiest suburban Boston commuter rail station at rush hour, but it’s still just about 2,000 weekday boardings, whereas RER and S-Bahn stations with 10 time the traffic hold to a 30-second standard. This also interacts positively with accessibility: it permits passengers in wheelchairs to board unaided, which both improves accessibility and ensures that a wheelchair user doesn’t delay the entire train by a minute. It is fortunate that the LIRR and (with one peripheral exception) Metro-North are entirely high-platform, and unfortunate that New Jersey Transit is not.
Reducing delay propagation
Even with reliable mechanical and civil engineering, delays are inevitable. The real innovations in Switzerland giving it Europe’s most reliable and highest-use railway network are not about preventing delays from happening (it is fully electrified but a laggard on level boarding). They’re about ensuring delays do not propagate across the network. This is especially notable as the network relies on timed connections and overtakes, both of which require schedule discipline. Achieving such discipline requires the following operations and capital treatments:
- Uniform timetable padding of about 7%, applied throughout the line roughly on a one minute in 15 basis.
- Clear, non-discriminatory rules about train priority, including a rule that a train that’s more than 30 minutes loses all priority and may not delay other trains at junctions or on shared tracks.
- A rigid clockface schedule or Takt, where the problem sections (overtakes, meets, etc.) are predictable and can receive investment. With the Takt system, even urban commuter lines can be left partly single-track, as long as the timetable is such that trains in opposite directions meet away from the bottleneck.
- Data-oriented planning that focuses on tracing the sources of major delays and feeding the information to capital planning so that problem sections can, again, receive capital investment.
- Especial concern for railway junctions, which are to be grade-separated or consistently scheduled around. In sensitive cases where traffic is heavy and grade separation is too expensive, Switzerland builds pocket tracks at-grade, so that a late train can wait for a slot without delaying cross-traffic.
So, how big do train stations need to be?
A multi-station urban commuter rail trunk can get away with metro-style operations, with a single station track per approach track. However, the limiting factor to capacity will be station dwell times. In cases with an unusually busy city center station, or on a highly-interlinked regional or intercity network, this may force compromises on capacity.
In contrast, with good operations, a train station with through-running should never need more than two station tracks per approach track. Moreover, the two station tracks that each approach track splits into should serve the same platform, so that if there is an unplanned rescheduling of the train, passengers should be able to use the usual platform at least. Berlin Hauptbahnhof’s deep tracks are organized this way, and so is the under-construction Stuttgart 21.
Why two? First, because it is the maximum number that can serve the same platform; if they serve different platforms, it may require lengthening dwell times during unscheduled diversions to deal with passenger confusion. And second, because every additional platform track permits, in theory, an increase in the dwell time equal to the minimum headway. The minimum headway in practice is going to be about 120 seconds; at rush hour Paris pushes 32 trains per hour on the shared RER B and D trunk, which is not quite mainline but is extensively branched, but the reliability is legendarily poor. With a two-minute headway, the two-platform track system permits a straightforward 2.5-minute dwell time, which is more than any regional railway needs; the Zurich S-Bahn has 60-second dwells at Hauptbahnhof, and the Paris RER’s single-level trains keep to about 60 seconds at rush hour in city center as well.
All of this is more complicated at a terminal. In theory the required number of tracks is the minimum turn time divided by the headway, but in practice the turn time has a variance. Tokyo has been able to push station footprint to a minimum, with two tracks at Tokyo Station on the Chuo Line (with 28 peak trains per hour) and, before the through-line opened, four tracks on the Tokaido Main Line (with 24). But elsewhere the results are less optimistic; Paris is limited to 16-18 trains per hour at the four-track RER E terminal at Saint-Lazare.
At Paris’s levels of efficiency, which are well below global best practices, an unexpanded Penn Station without through-running would still need two permanent tracks for Amtrak, leaving 19 tracks for commuter traffic. With the Gateway tunnel built, there would be four two-track approaches, two from each direction. The approaches that share tracks with Amtrak (North River Tunnels, southern pair of East River Tunnels) would get four tracks each, enough to terminate around 18 trains per hour at rush hour, and the approaches that don’t would get five, enough for maybe 20 or 22. The worst bottleneck in the system, the New Jersey approach, would be improved from today’s 21 trains per hour to 38-40.
A Penn Station with through-running does not have the 38-40 trains per hour limit. Rather, the approach tracks would become the primary bottleneck, and it would take an expansion to eight approach tracks on each side for the station itself to be at all a limit.
The Italy case, done by Marco Chitti, is up on the website. I encourage people to read the entire report on how Italy has set things up in the last 20-30 years so as to have one of the lowest-cost urban rail infrastructure programs in the world. The Turkey case, by Elif Ensari, will be up shortly.
This is leading to a webinar, to be done tomorrow at 16:00 my time, 10:00 New York time, in which Marco and Elif will present their cases to the general public. I encourage people to register; you’ll be able to ask us questions and we’ll answer in chat or on video. But if you can’t make it, it will be recorded.