I did a complex Patreon poll about series to write about. In the poll about options for transit network design the winning entry was difficult urban geography, covered here and here; the runner-up was cross-platform transfers.
Subway users have usually had the experience of connecting at a central station so labyrinthine they either were lost or had to walk long distances just to get to their onward train. Parisians know to avoid Chatelet and New Yorkers know to avoid Times Square. It’s not just an issue for big cities: every metro system I remember using with more than one line has such stations, such as T-Centralen in Stockholm, Waterfront in Vancouver, and Dhoby Ghaut in Singapore. To prevent such connections from deterring passengers, some cities have invested in cross-platform interchanges, which permit people to transfer with so little hassle that in some ridership models, such as New York’s, they are treated as zero-penalty, or equivalent to not having to transfer at all.
Unfortunately, improving the transfer experience is never as easy as decreeing that all interchanges be cross-platform. While these connections are always better for passengers than the alternative, they are not always feasible, and even when feasible, they are sometimes too expensive.
Cross-platform transfer to wherest?
Consider the following two-line subway interchange:
A cross-platform transfer involves constructing the station in the center so that the north-south and east-west lines have platforms stacked one on top of the other, with each east-west track facing a north-south track at the same platform. The problem: do eastbound trains pair up with northbound ones and westbound trains with southbound ones, or the other way around?
In some cases, there is an easy answer. If two rail lines heading in the same general direction happen to cross, then this provides a natural pairing. For example, the Atlantic Branch and Main Line of the LIRR meet at Jamaica Station, where the cross-platform transfer pairs westbound with westbound trains and eastbound with eastbound trains. In Vienna, this situation occurs where U4 and U6 intersect: there is a clear inbound direction on both lines and a clear outbound lines, so inbound pairs with inbound and outbound with outbound.
However, in most cases, the transfer is within city center, and there is no obvious pairing. In that case, there are two options.
Near-cross platform transfer
Some transfers are nearly cross-platform. That is to say, they have trains on two levels, with easy vertical circulation letting people connect between all four directions. In Berlin, there is such a transfer at Mehringdamm between U6 and U7 – and in the evening, when trains come every 10 minutes, they are scheduled to offer a four-way timed interchange, waiting for connecting passengers even across a level change.
Multi-station transfer complex
Singapore, Stockholm, and Hong Kong all offer cross-platform transfers in multiple directions by interweaving two lines for two or three consecutive stations. The three-station variant is as in the following diagram:
At the two outer transfer stations, the cross-platform connections are wrong-way relative to the shared trunk corridor: eastbound pairs with northbound, westbound pairs with southbound. At the middle station, connections are right-way: eastbound pairs with southbound, westbound pairs with northbound.
Of note, the shared trunk has four tracks and no track sharing between the two different subways. I’ve proposed this for the North-South Rail Link. The reason three stations are needed for this and not two is that with only two stations, passengers would have to backtrack in one pairing. Nonetheless, backtracking is common: Stockholm has three stations for the transfer between the Green and Red Lines but only the northern one is set up for wrong-way transfers, so passengers connecting wrong-way in the south have to backtrack, and Singapore has two stations between the East-West and North-South Lines, since one of the pairings, west-to-south, is uncommon as the North-South Line extends just one station south of the transfer.
Why are they not more widespread?
The inconvenience of Parisian transfers is a general fact, and not just at Chatelet. Two lines that meet usually meet at right angles, and the platforms form a right angle rather than a plus sign, so passengers have to be at one end of the train to have easy access to the connecting platforms. The reason for this is that Paris built the Metro cut-and-cover, and there was no space to reorient lines to have cross-platform transfers.
In contrast, both Stockholm and Singapore had more flexibility to work with. Singapore deep-bored the MRT for reasons of civil defense, contributing to its recent high construction costs; the tradeoff is that deep boring does permit more flexibility underneath narrow streets, which all streets are compared with the footprint of a cross-platform interchange. Stockholm used a mixture of construction methods, but the four-track trunk carrying the Green and Red Lines is above-ground in the Old City but was built with a sunk caisson at T-Centralen.
In London, similarly, there are cross-platform transfers, involving the Victoria line. It was built in the 1960s around older infrastructure, but at a few spots in Central London, the tubes were built close enough to old lines to permit cross-platform interchange in one direction (northbound-to-northbound, southbound-to-southbound). In contrast, the surface network, constrained by land availability, does not feature easy interchanges.
While deep boring makes cross-platform transfers easier, either can exist without the other. If I understand this correctly, U6 was built cut-and-cover. There were even weaves on the IND in New York, but they were expensive. Moreover, when two lines are built under a wide street with two branching streets, rather than on something like a grid (or even Paris’s street network, which is gridded at key places like where M4 runs under Sevastopol), cut-and-cover construction can produce a cross-platform transfer. Conversely, such transfers do not exist in all-bored Moscow and are rare in London.
The importance of planning coordination
Ultimately, cross-platform transfers boil down to coordinated planning. Some cities can’t build them even with coordination – Paris is a good example – but absent coordination, they will not appear no matter how good the geography is. Stockholm, Berlin, Vienna, Singapore, and Hong Kong are all examples of centrally planned metro networks, without the haphazard additions of New York (which was centrally planned on three separate occasions) or London (where the early lines were built privately).
Even with coordination, it is not guaranteed cross-platform transfers will appear, as in Moscow. Planners must know in advance which lines they will build, but they must also care enough about providing a convenient transfer experience. This was not obvious when Moscow began building its metro, and regrettably is still not obvious today, even though the benefits are considerable. But planners should have the foresight to design these transfers when possible in order to reduce passenger trip times; ultimately it is unlikely to cost more than providing the same improvements in trip times through faster trains.
The Boston rapid transit network has the shape of the hex symbol, #. In Downtown Boston, the two north-south legs are the Green Line on the west and the Orange Line on the east, and the two east-west legs are the Red Line on the south and the Blue Line on the north. The Orange and Green Lines meet farther north, but the Red and Blue Lines do not. The main impact of this gap in systemwide connectivity is that it’s really hard to get between areas only served by the Blue Line, i.e. East Boston, and ones only served by the Red Line, i.e. Cambridge, Dorchester, and Quincy. However, there is a second impact: people who do transfer between the Red and Blue Lines overload one central transfer point at Park Street, where the Red and Green Lines meet. This way, the weak connectivity of the Boston rapid transit network creates crowding at the center even though none of the individual lines is particularly crowded in the center. The topic of this post is then how crowding at transfer points can result from poor systemwide connectivity.
The current situation in Boston
Connecting between the Blue and Red Lines requires a three-seat ride, with a single-stop leg on either the Orange or Green Line. In practice, passengers mostly use the Green Line, because the Orange Line has longer transfer corridors.
Travel volumes between East Boston and Cambridge are small. Only 1,800 people commute from East Boston, Winthrop, and the parts of Revere near the Blue Line to Cambridge, and only 500 commute in the other direction. I don’t have data on non-work travel, but anecdotally, none of the scores of Cantabrigians I know travels to the Blue Line’s service area except the airport, and to the airport they drive or take the Silver Line, and moreover, only two people moved from Cambridge or Somerville to the area, a couple that subsequently left the region for Bellingham. Travel volumes between East Boston and the southern legs of the Red Line are barely larger: 1,200 from East Boston to Dorchester, Mattapan, and Quincy, 1,600 in the other direction, most likely not taking public transit since cars are a good option using the Big Dig.
Nonetheless, this small travel volume, together with connections between East Boston and South Station or Dorchester, is funneled through Park Street. According to the 2014 Blue Book, which relies in 2012 data, transfer volumes at Park Street are 29,000 in each direction (PDF-p. 16), ahead of the Red/Orange connection at Downtown Crossing, where 25,000 people transfer in each direction every weekday. Riders connecting between the Blue and Red Lines are a noticeable proportion of this volume – the East Boston-Cambridge connection, where I believe the transit mode share is high, is around 8% of the total, and then the East Boston-Dorchester connection would add a few more percentage points.
Why Soviet triangles exist
In a number of metro networks, especially ones built in the communist bloc, there are three lines meeting in a triangle, without a central transfer point. This is almost true of the first three subway lines in Boston, omitting the Red Line: they meet in a triangle, but the Green and Orange Lines do not cross, whereas in true Soviet triangles lines meet and cross.
The reason for this typology rather than for the less common one in which all three lines meet at one station, as in Stockholm, is that it spreads transfer loads. Stockholm’s transfer point, T-Centralen, has 184,000 daily boardings (source, PDF-p. 13), almost as many as Times Square, which is served by 14 inbound tracks to T-Centralen’s 5 and is in a city with 5.6 million weekday trips to Stockholm’s 1.1 million. Urban transit networks should avoid such situations, which lead to central crowding that is very difficult to alleviate. Adding pedestrian circulation is always possible, but is more expensive at a multilevel central station than at a simple two-line crossing.
The triangle is just a convenient way of building three lines. As the number of lines grows beyond three, more connectivity is needed. Moscow’s fourth line, Line 5, is a circle, constructed explicitly to decongest the central transfer station between the first three lines. More commonly, additional lines are radials, especially in cities with water constraints that make circles difficult, like Boston and New York; but those should meet all the older radii, ideally away from existing transfer stations in order to reduce congestion. When they miss connections, either by crossing without interchange or by not crossing at all, they instead funnel more cross-city traffic through the existing transfer points, increasing ridership without increasing the capacity required to absorb it.
The way out
The situation is usually hard to fix. It’s much harder to fix missed connections, or parallel lines that diverge in both directions, than to connect two parallel lines when one of these lines terminates in city center, which Boston’s Blue Line does. The one saving grace is that cities with many missed connections, led by New York and Tokyo, also have very expansive networks with so many transfer points that individual interchanges do not become overloaded.
In large cities that do have problems with overcrowded transfer points, including London and Paris, the solution is to keep building out the network with many connections. London tries to weaken the network by reducing transfer opportunities: thus, Crossrail has no connection to Oxford Circus, the single busiest non-mainline Underground station, in order to prevent it from becoming any more crowded, and the Battersea extension of the Northern line deliberately misses a connection to the Victoria line. Paris has a better solution – it invests in circumferential transit, in the form of Metro Line 15 ringing the city at close distance, as well as extensions to Tramway Line 3, just inside city limits.
While the solution always involves investing more in the transit network, its precise nature depends on the city’s peculiar geography. In Paris, a compact city on a narrow river, adding more circles is an option, as is adding more RER lines so that people would be able to avoid difficult Metro-to-RER transfers. In London, the population density is too low and the construction costs are too high for a greenfield circle; the existing circle, the Overground, is cobbled together from freight bypasses and is replete with missed radial Underground connections. Thus, the solution in London has to come from radials that offer alternatives to the congestion of the Victoria line.
In Boston, a much smaller city, the Red-Blue Connector is easier since the Red and Blue Lines almost touch. It only takes about 600 meters of cut-and-cover tunnel under a wide road to continue the Blue Line beyond its current terminus in Downtown Boston and meet the Red Line at Charles-MGH; to first order, it should cost not much more than $100 million. The transfer would not be easy, since the Red Line is elevated there and the Blue Line would be underground, but it would still be better than the three-seat ride involving the Green Line. A competent state government with interest in improving transportation connectivity for its residents – that is, a government that is nothing like the one Massachusetts has – would fix this problem within a few years. Boston is fortunate in not needing painful deep tunneling under a medieval city center like London or hundreds of kilometers of inner suburban tunneling like Paris – it only needs to kick out the political bums, unfortunately a much harder task.
I did a complex Patreon poll about series to write about. People voted for general transit network design, and more posts about national traditions of transit in the mold of the one about the US. Then I polled options for transit network design. There were six options, and people could vote up or down on any. Difficult urban geography was by far the most wanted, and three more alternatives hover at the 50% mark. To give the winning option its due course, I’m making it a mini-series of its own.
There are cities that, due to their street layout, make it easy to run transit on them. Maybe they are flat and have rivers that are easy to bridge or tunnel under. Maybe they have a wealth of wide arterials serving the center, with major cross streets at exactly the right places for stations and an underlying bus grid. Maybe they spread out evenly from the center so that it’s easy to run symmetric lines. Maybe their legacy mainline rail network is such that it’s easy to run interpolating buses and urban rail lines.
And then there are cities that are the exact opposite. In this post I’m going to focus on narrow or winding streets and what they mean for both surface and rapid transit. The good fortune for transit planners is that the city that invented urban rapid transit, London, is a prime example of difficult urban geography, so railway engineers have had to deal with this question for about 150 years, inventing some of the necessary technology in the process.
Rapid transit with narrow streets
The easiest ways to build rapid transit are to put it on a viaduct and to bury it using cut-and-cover tunneling. Both have a minimum street width for the right-of-way – an el requires about 10 meters, but will permanently darken the street if it is not much wider, and a tunnel requires about 10 meters for the tracks but closer to 18 for the stations.
Nonetheless, even cities with narrow streets tend to have enough streets of the required width. What they don’t always have is streets of the required width that are straight and form coherent spines. The labyrinth that is Central London does have wide enough streets for cut-and-cover, but they are not continuous and often miss key destinations such as major train stations. The Metropolitan line could tunnel under Euston Road, but the road’s natural continuation into the City is not so wide, forcing the line to carve a trench into Farringdon. Likewise, the District line could tunnel under Brompton Road or King’s Road, but serving Victoria and then Westminster would have required some sharp curves, so the District Railway carved a right-of-way, demolishing expensive Kensington buildings at great expense.
While London is the ur-example, as the city that invented the subway, this situation is common in other cities with large premodern cores, such as Rome, Milan, and Istanbul. Paris only avoided this problem because of Haussmann’s destruction of much of the historic city, carving new boulevards for aesthetics and sewer installation, which bequeathed the Third Republic a capital rich in wide streets for Metro construction.
Dealing with this problem requires one of several solutions, none great:
London’s solution was to invent the tunnel boring machine to dig deep Tube lines, avoiding surface street disruption. With electric-powered trains and reliable enough TBMs to bore holes without cave-ins, London opened the Northern line in 1890, crossing the Thames to provide rapid transit service to South London. Subsequently, London has built nearly all Underground lines bored, even in suburban areas where it could have used cut-and-cover.
The main advantage to TBMs is that they avoid surface disruption entirely. Most first-world cities use them to bore tunnels between stations, only building stations cut-and-cover. The problem is that TBMs are more expensive to use than cut-and-cover today. While turn-of-the-century London built Tube lines for about the same cost per km as the Metropolitan line and as the cut-and-cover Paris Metro and New York City Subway, in the last half century or so the cost of boring has risen faster than that of shallow construction.
The worst is when the stations have to be mined as well. Mining stations has led to cost blowouts in New York (where it was gone gratuitously) and on London Crossrail (where it is unavoidable as the tunnel passes under the older Underground network). A city that cannot use cut-and-cover tunnels needs to figure out station locations that are easily accessible for vertical digging.
The alternative is the large-diameter TBM. Barcelona is using this technique for Line 9/10, which passes under the older lines; the city has a grid of wide boulevards, but the line would still have to pass under the older metro network, forcing the most difficult parts to be deep underground. The large-diameter TBM reduces the extent of construction outside the TBM to just an elevator bank, which can be dug in a separate vertical TBM; if higher capacity is desired, it’s harder but still possible to dig slant bores for escalators. The problem is that this raises construction costs, making it a least bad solution rather than a good one; Barcelona L9, cheap by most global standards, is still expensive by Spanish ones.
Carving new streets
Before the 1880s, London could not bore the Underground, because the steam-powered trains would need to be close to surface for ventilation. Both the Metropolitan and District lines required carving new right-of-way when streets did not exist; arguably, the entire District line was built this way, as its inner segment was built simultaneously with the Victoria Embankment, under which it runs. The same issue happened in New York in the 1910s and again in the 1920s: while most of the city is replete with straight, wide throughfares, Greenwich Village is not, which forced the 1/2/3 to carve what is now Seventh Avenue South and later the A/C/E to carve the southern portions of Sixth Avenue.
This solution is useful mostly when there are wide streets with absolutely nothing between them that a subway could use. The reason is that demolishing buildings is expensive, except in very poor or peripheral areas, and usually rapid transit has to run to a CBD to be viable. If the entire route is hard to dig, a TBM is a better solution, but if there are brief narrows, carving new streets New York did could be useful, especially if paired with improvements in surface transit.
Looking for station sites
Milan built its first metro lines cut-and-cover. However, lacking wide streets, it had to modify the method for use in a constrained environment. Instead of digging the entire street at a sloped angle and only then adding retaining walls, Milan had to dig the retaining walls first, allowing it to dig up streets not much wider than two tracks side by side. This method proved inexpensive: if I understand this article right, the cost was 30 billion lire in 1957-1964 prices, which is €423 million in 2018 prices, or €35 million per km. Milan’s subsequent construction costs have remained low, even with the use of a TBM for Metro Line 5.
The problem with this method is that, while it permits digging tunnels under narrow medieval streets, it does not permit digging stations under the same streets. Milan is fortunate that its historical center is rich in piazzas, which offer space for bigger digs. One can check on a satellite map that every station on Lines 1 and 2 in city center is at a piazza or under a wide street segment; lacking the same access to easy station sites, Line 3 had to be built deeper, with tracks stacked one under the other to save space.
I have argued in comments that Paris could have used this trick of looking for less constrained sites for stations when it built Metro Line 1, permitting four tracks as in New York as long as the express stations under Rue de Rivoli stuck to major squares like Chatelet. However, Paris, too, is rich in squares, it just happens to be equally rich in wide streets so that it did not need to use the Milan method. London is not so fortunate – its only equivalent of Milan’s piazzas is small gardens away from major streets. It could never have built the Central line using the Milan method, and even the Piccadilly line, which partly passes under wide streets, would have been doubtful.
Rapid transit benefits from being able to modify the shape of the street network to suit its needs. Surface transit in theory could do the same, running in short tunnels or widening streets as necessary, but the value of surface modes is not enough to justify the capital expense and disruption. Thus, planners must take the street network as it is given. The ideal surface transit route runs in the street median on two dedicated lanes, with boarding islands at stops; creating a parking lane, a moving lane, and a transit lane in each direction on a street plus some allowance for sidewalks requires about 30 meters of street width or not much less. Below 25, compromises are unavoidable.
Cutting car lanes
A lane is about 3 meters wide, so removing the parking lanes reduces the minimum required street width by about 6 meters. Contraflow lanes instead allow the street to have the same four lanes, but with a moving lane and a parking lane in one direction only. In extreme cases it’s possible to get rid of the cars entirely; a transit mall is viable down to maybe 12-15 meters of street width. The problem is that deliveries get complicated if the city doesn’t have alleyways or good side street access, and this may force compromises on hours of service (perhaps transit doesn’t get dedicated lanes all day) or at least one parking lane in one direction.
Some city cores with very narrow streets don’t have double-track streetcars. A few have one-way pairs, but more common is single-track segments, or segments with two overlapping tracks so that no switching is needed but trams still can’t pass each other. Needless to say, single-tracking is only viable over short narrows between wider streets, and only when the network is punctual enough that trams can be scheduled not to conflict.
On longer stretches without enough room for two tracks or two lanes, one-way pairs are unavoidable; these complicate the network, and unless the streets the two directions of the bus or tram run on are very close to each other they also complicate interchanges between routes. New York has many one-way pairs on its bus network, even on wide and medium-width streets in order to improve the flow of car traffic, and as a result, some crosstown routes, such as the B35 on Church, are forced to stop every 250 meters even when running limited-stop. While New York’s network complexity is the result of bad priorities and can be reversed, cities with premodern street networks may not even have consistent one-way pairs with two parallel streets on a grid; New York itself has such a network in Lower Manhattan.
Bus network redesign
The best way to avoid the pain associated with running buses on streets that are not designed for fast all-mode travel is not to run buses on such streets. Boston has very little surface transit in city center, making passengers transfer to the subway. In Barcelona, part of the impetus for Nova Xarxa was removing buses from the historic core with its narrow streets and traffic congestion and instead running them on the grid of the Eixample, where they would not only provide a frequent system with easy transfers but also run faster than the old radial network.
However, this runs into two snags. First, there must be some radial rapid transit network to make people connect to. Boston and Barcelona both have such networks, but not all cities do; Jerusalem doesn’t (it has light rail but it runs on the surface). And second, while most cities with a mixture of wide and narrow streets confine their narrow streets to premodern historic cores, some cities have streets too narrow for comfortable bus lanes even far out, for example Los Angeles, whose north-south arterials through the Westside are on the narrow side.
What not to do: shared lanes
It’s tempting for a transit agency to compromise on dedicated lanes whenever the street is too narrow to feature them while maintaining sufficient auto access. This is never a good idea, except in outlying areas with little traffic. The reason is that narrow streets fed by wide streets are precisely where there is the most congestion, and thus where the value of dedicated transit lanes is the highest.
In New York, the dedicated bus lanes installed for select bus service have sped up bus traffic by around 30 seconds per kilometer on all routes Eric Goldwyn and I have checked for our Brooklyn bus redesign project, but all of these figures are averaged over long streets. Within a given corridor, the short narrows that the transit agency decides to compromise on may well feature greater time savings from dedicated lanes than the long arterial stretch where it does set up dedicated lanes. This is almost certainly the case for the Silver Line in Boston, which has unenforced dedicated lanes most of the way on Washington Streets but then uses shared lanes through Downtown Boston, where streets are too narrow for dedicated lanes without reducing auto access.
The Geary corridor in San Francisco is a neat model for transit ridership. The Golden Gate Park separates the Richmond District from the Sunset District, so the four east-west buses serving the Richmond – the 38 on Geary itself and the closely parallel 1 California, 31 Balboa, and 5 Fulton – are easy to analyze, without confounding factors coming from polycentric traffic. Altogether, the four routes in all their variations have 114,000 riders per weekday. The 38 and 1 both run frequently – the 1 runs every 5-6 minutes in the weekday off-peak, and the 38 runs every 5 minutes on the rapid and every 8 on the inner local.
I was curious about the connection between development and travel demand, so I went to OnTheMap to check commute volumes. I drew a greater SF CBD outline east of Van Ness and north of the freeway onramp and creek; it has 420,000 jobs (in contrast, a smaller definition of the CBD has only 220,000). Then I looked at how many people commute to that area from due west, defined as the box bounded by Van Ness, Pacific, the parks, and Fell. The answer is 28,000. Another 3,000 commute in the opposite direction.
Put another way: the urban transit system of San Francisco carries about twice as many passengers on the lines connecting the Richmond and Japantown with city center as actually make that commute: 114,000/2*(28,000 + 3,000) is 1.84. This represents an implausible 184% mode share, in a part of the city where a good number of people own and drive cars, and where some in the innermost areas could walk to work. What’s happening is that when the transit system is usable, people take it for more than just their commute trips.
The obvious contrast is with peak-only commuter rail. In trying to estimate the potential ridership of future Boston regional rail, I’ve heavily relied on commute volumes. They’re easier to estimate than overall trip volumes, and I couldn’t fully get out of the mindset of using commuter rail to serve commuters, just in a wider variety of times of day and to a wider variety of destinations.
In Boston, I drew a greater CBD that goes as far south as Ruggles and as far west as Kendall; it has a total of 370,000 jobs. Of those, about 190,000 come from areas served by commuter rail and not the subway or bus trunks, including the southernmost city neighborhoods like Mattapan and Hyde Park, the commuter rail-adjacent parts of Newton, and outer suburbs far from the urban transit system. But MBTA commuter rail ridership is only about 120,000 per weekday. This corresponds to a mode share of 32%.
I tried to calculate mode shares for the MBTA seven years ago, but that post only looked at the town level and excluded commuter rail-served city neighborhoods and the commuter rail-adjacent parts of Newton, which contribute a significant fraction of the total commute volume. Moreover, the post included suburban transit serving the same zones, such as ferries and some express buses; combined, the mode share of these as well as commuter rail ranged from 36% to 50% depending on which suburban wedge we are talking about (36% is the Lowell Line’s shed, 50% is the Providence Line’s shed). Overall, I believe 32% is consistent with that post.
Part of the difference between 32% and 184% is about the tightness of economic integration within a city versus a wider region. The VA Hospital in San Francisco is located in the Outer Richmond; people traveling there for their health care needs use the bus for this non-commuter trip. On a regional level, this never happens – people drive to suburban hospitals or maybe take a suburban bus if they are really poor.
That said, hospital trips alone cannot make such a large difference. There are errand trips that could occur on a wider scale if suburban transit were better. Cities are full of specialty stores that people may travel to over long distances.
For example, take gaming. In Vancouver I happened to live within walking distance of the area gaming store, but during game nights people would come over from Richmond; moreover, the gaming bar was in East Vancouver, and I’d go there for some social events. In Providence I’d go to Pawtucket to the regional gaming store. In the Bay Area, the store I know about is in Berkeley, right on top of the Downtown Berkeley BART station, and I imagine some people take BART there from the rest of the region.
None of this can happen if the region is set up in a way that transit is only useful for commute trips. If the trains only come every hour off-peak, they’re unlikely to get this ridership except in extreme cases. If the station placement is designed around car travel, as is the case for all American commuter lines and some suburban rapid transit (including the tails of BART), then people will just drive all the way unless there’s peak congestion. Only very good urban transit can get this non-work ridership.
While electric cars remain a niche technology, electric buses are surging. Some are battery-electric (this is popular in China, and some North American agencies are also buying into this technology), but in Europe what’s growing is in-motion charging, or IMC. This is a hybrid of a trolleybus and a battery-electric bus (BEB): the bus runs under wire, but has enough battery to operate off-wire for a little while, and in addition has some mechanism to let the bus recharge during the portion of its trip that is electrified.
One vendor, Kiepe, lists recent orders. Esslingen is listed as having 10 km of off-wire capability and Geneva (from 2012) as having 7. Luzern recently bought double-articulated Kiepe buses with 5 km of off-wire range, and Linz bought buses with no range specified but of the same size and battery capacity as Luzern’s. Iveco does not specify what its range is, but says its buses can run on a route that’s 25-40% unwired.
Transit planning should be sensitive to new technology in order to best integrate equipment, infrastructure, and schedule. Usually this triangle is used for rail planning, but there’s every reason to also apply it to buses as appropriate. This has a particular implication to cities that already have large trolleybus networks, like Vancouver, but also to cities that do not. IMC works better in some geographies than others; where it works, it is beneficial for cities to add wire as appropriate for the deployment of IMC buses.
Vancouver: what to do when you’re already wired
Alert reader and blog supporter Alexander Rapp made a map of all trolleybus routes in North America. They run in eight cities: Boston, Philadelphia, Dayton, San Francisco, Seattle, Vancouver, Mexico City, Guadalajara.
Vancouver’s case is the most instructive, because, like other cities in North America, it runs both local and rapid buses on its trunk routes. The locals stop every about 200 meters, the rapids every kilometer. Because conventional trolleybuses cannot overtake other trolleybuses, the rapids run on diesel even on wired routes, including Broadway (99), 4th Avenue (44, 84), and Hastings (95, 160), which are in order the three strongest bus corridors in the area. Broadway has so much ridership that TransLink is beginning to dig a subway under its eastern half; however, the opening of the Broadway subway will not obviate the need for rapid buses, as it will create extreme demand for nonstop buses from the western end of the subway at Arbutus to the western end of the corridor at UBC.
IMC is a promising technology for Vancouver, then, because TransLink can buy such buses and then use their off-wire capability to overtake locals. Moreover, on 4th Avenue the locals and rapids take slightly different routes from the western margin of the city proper to campus center, so IMC can be used to let the 44 and 84 reach UBC on their current route off-wire. UBC has two separate bus loops, one for trolleys and one for diesel buses, and depending on capacity IMC buses could use either.
On Hastings the situation is more delicate. The 95 is not 25-40% unwired, but about 60% unwired – and, moreover, the unwired segment includes a steep mountain climb toward SFU campus. The climb is an attractive target for electrification because of the heavy energy consumption involved in going uphill: at 4 km, not electrifying it would brush up against the limit of Kiepe’s off-wire range, and may well exceed it given the terrain. In contrast, the 5 km in between the existing wire and the hill are mostly flat, affording the bus a good opportunity to use its battery.
Where to add wire
In a city without wires, IMC is the most useful when relatively small electrification projects can impact a large swath of bus routes. This, in turn, is most useful when one trunk splits into many branches. Iveco’s requirement that 60-75% of the route run under wire throws a snag, since it’s much more common to find trunks consisting of a short proportion of each bus route than ones consisting of a majority of route-length. Nonetheless, several instructive examples exist.
In Boston, the buses serving Dorchester, Mattapan, and Roxbury have the opportunity to converge to a single trunk on Washington Street, currently hosting the Silver Line. Some of these buses furthermore run on Warren Street farther south, including the 14, 19, 23, and 28, the latter two ranking among the MBTA’s top bus routes. The area has poor air quality and high rates of asthma, making electrification especially attractive.
Setting up wire on Washington and Warren Streets and running the Silver Live as open BRT, branching to the south, would create a perfect opportunity for IMC. On the 28 the off-wire length would be about 4.5 km each way, at the limit of Kiepe’s capability, and on the 19 and 23 it would be shorter; the 14 would be too long, but is a weaker, less frequent route. If the present-day service pattern is desired, the MBTA could still electrify to the northern terminus of these routes at Ruggles, but it would miss an opportunity to run smoother bus service.
In New York, there are examples of trunk-and-branch bus routes in Brooklyn and Queens. The present-day Brooklyn bus network has a long interlined segment on lower Fulton, carrying not just the B25 on Fulton but also the B26 on Halsey and B52 on Gates, and while Eric Goldwyn’s and my plan eliminates the B25, it keeps the other two. The snag is that the proportion of the system under wire is too short, and the B26 has too long of a tail (but the B52 and B25 don’t). The B26 could get wire near its outer terminal, purposely extended to the bus depot; as bus depots tend to be polluted, wire there is especially useful.
More New York examples are in Queens. Main Street and the Kissena-Parsons corridor, both connecting Flushing with Jamaica, are extremely strong, interlining multiple buses. Electrifying these two routes and letting buses run off-wire on tails to the north, reaching College Point and perhaps the Bronx on the Q44 with additional wiring, would improve service connecting two of Queens’ job centers. Moreover, beyond Jamaica, we see another strong trunk on Brewer Boulevard, and perhaps another on Merrick (interlining with Long Island’s NICE bus).
Finally, Providence has an example of extensive interlining to the north, on North Main and Charles, including various 5x routes (the map is hard to read, but there are several routes just west of the Rapid to the north).
IMC and grids
The examples in New York, Providence, and Boston are, not coincidentally, ungridded. This is because IMC interacts poorly with grids, and it is perhaps not a coincidence that the part of the world where it’s being adopted the most has ungridded street networks. A bus grid involves little to no interlining: there are north-south and east-west arterials, each carrying a bus. The bus networks of Toronto, Chicago, and Los Angeles have too little interlining for IMC to be as cost-effective as in New York or Boston.
In gridded cities, IMC is a solution mainly if there are problematic segments, in either direction. If there’s a historic core where wires would have adverse visual impact, it can be left unwired. If there’s a steep segment with high electricity consumption, it should be wired preferentially, since the cost of electrification does not depend on the street’s gradient.
Overall, this technology can be incorporated into cities’ bus design. Grids are still solid when appropriate, but in ungridded cities, trunks with branches are especially attractive, since a small amount of wire can convert an entire swath of the city into pollution-free bus operation.
American progressive media is talking about the possibility of a Green New Deal, which involves spending money in a way that reduces greenhouse gas emissions. So far details are scant, and most likely no real plan is likely to emerge for a number of years, since the proposal is pushed by the Democratic base, which is no more supportive of cooperation with President Trump than I am. Because the plan is so early, people are opining about what should go in it. My purpose in this post is to explain what I think the main priorities should be, and to leave to others the politics of how to package them.
The primacy of transportation
The main sources of greenhouse gas emissions are transportation, electricity generation, and industry. In the US this is in descending order, transportation having just overtaken power generation; the reduction in coal burning and the collapse in solar power production costs are such that in the long term, electricity generation should be viewed as a solved problem in the long term. Lingering issues with storage and base load are real, but the speed of progress is such that ordinary taxes on carbon should be enough to fix whatever is left of the problem.
Transportation is the exact opposite. American transportation emissions fell in the 2007-8 oil price spike and ensuing economic crisis but are now increasing again. Newer cars have higher fuel efficiency, but Americans are buying bigger cars and driving more. Electric cars, the favored solution of people who think spending $50,000 on a new car is reasonable, are still a niche luxury market and have trouble scaling up. Scratch an American futurist who looks exclusively at electric cars and denigrates mass transit and you’ll wound a solipsist who looks for excuses to avoid the humiliation of having to support something where other countries lead and the US lags.
The upshot is that the primary (but not the only) focus of any green push has to be expansion of public transportation. This includes ancillary policies for urban redevelopment and livable streets, which have the dual effects of buttressing public transit and reducing residential emissions through higher-density living. Overall, this turns any such program into a large public works project.
Spend money right
It’s paramount to make sure to avoid wasting money. A large infrastructure program would run into an appreciable fraction of federal spending; money is always a constraint, even when the goal is to spend funds on economic stimulus. The first lesson here is to keep construction costs under control. But an equally fundamental lesson is to make sure to spend money on transit expansion and not other things:
Don’t spend money on roads
A large majority of American public spending on transportation is on roads. Adding in subsidies for cars makes the proportion go even higher. It reflects current travel patterns, but if the goal is to reduce the environmental footprint of driving, the government can’t keep pumping money into road infrastructure. Accept that in developed countries the generally useful roads have already been built, and future construction just induces people to suburbanize further and drive longer distances.
Congress spends transportation money in multi-year chunks. The most recent bill passed in 2015 for five years, totaling $300 billion, of which $50 billion went to public transit and $200 billion went to highways. Raiding the road fund should be the primary source of additional transit funding: most of the line workers and engineers can build either, and even the physical act of building a freeway is not too different from that of building a high-speed railway. In contrast, outside of a deep recession, increasing total spending on transportation infrastructure requires hiring more workers, leading to large increases in costs as the program runs up against the limit of the available construction labor in the country.
$60 billion a year on public transit is a decent chunk of money for a long-term program, especially with expected state matches. Over the next decade it would be $600 billion, and around a trillion with state and local matches, if they are forthcoming (which they may not be because of how political incentives are lined up). That is, it’d a decent chunk of money if the federal government understands the following rule:
Fund expansion, not maintenance or operations
The sole legitimate source of regular budgeting for public transit is regular spending at the relevant level of government, which is state or local in the United States. Outside infusions of money like federal spending are bad government, because they incentivize deferring maintenance when the federal government is stingy and then crying poverty when it is generous. Amtrak did just that in the 2000s: faced with pressure from the Bush administration to look profitable for future privatization, Amtrak fired David Gunn, who wouldn’t defer maintenance, and replaced him with the more pliable Joe Boardman; then in the economic crisis and the stimulus, it discovered a multi-billion dollar backlog of deferred maintenance, permitting it to ask for money without having to show any visible results.
If the federal government credibly commits to not funding state of good repair backlogs or normal replacement, and to penalizing agencies that defer maintenance and giving them less money for expansion, it can encourage better behavior. Unlike ongoing maintenance, capital expansion is not necessary for continued operations, and thus if funding dries up and a transit agency stops expanding, there will not be problems with service cancellation, slow zones, frequency-ridership spirals, and other issues familiar to New Yorkers in the 1970s or Washingtonians today.
One potential way to change things is to federally fund expansion without expecting much if any local match, provided the agency commits to spending the required operating funds on running the service in question. This separation of federal and local responsibility also reduces the political incentives to grandstand by rejecting federal money in order to make the president look bad.
Build the rail lines that are appropriate
Each region in the US should be getting transit expansion money in rough proportion to its population. However, the meaning of transit depends on the local and regional geography:
- In big cities it means rapid transit expansion: new lines for the New York City Subway, the Chicago L, etc. In somewhat smaller cities with light rail-based systems it means light rail expansion, which may also involve upgrading at-grade light rail to full rapid transit: Dallas is considering a downtown tunnel for its light rail network and Los Angeles is already building one, and those could lead to upgrading capacity elsewhere on the system to permit longer trains.
- In suburbs and some smaller cities with large mainline rail networks, it means commuter rail. It’s especially valuable in the Northeast and secondarily in the Midwest and the odd older Southern city: cities like Milwaukee and Cincinnati don’t really have compelling corridors for greenfield urban rail, but do have interesting S-Bahn corridors.
- In periurban and rural areas, it means longer-range regional rail, transitioning to intercity rail in lower-density areas. In some smaller metro areas, it means actual intercity rail to bigger cities. Examples include Colorado Springs and Fort Collins, both of which can be connected with Denver, and Hans-Joachim Zierke’s proposed regional rail line for Medford, Oregon.
I focus on rail and not buses for two simple reasons: rail has higher capital and lower operating costs, so it’s more relevant for a capital program, and rail gets higher ridership for reasons including better right-of-way quality and better ride quality.
Transmit knowledge of best practices
The federal government has the ability to assimilate best practices for both limiting construction costs and designing good transit networks. Local governments can learn the same, but for the most part they don’t care. Instead they run their transit systems in manage-the-decline mode, only occasionally hearing about something done in London, hardly the best-run European transit city.
The best practices for network design are especially important given the magnitude of the program. The US is not spending $60 billion nationwide a year on transit expansion. The NTD says annual spending on capital among the top 50 American transit agencies was $14.6 billion as of 2016 (source, PDF-p. 11), and a lot of that (e.g. most of the MTA’s $3.5 billion capital expenditure) is the black holes that are state of good repair and normal replacement. $60 billion a year apportioned by population is on the order of $2 billion for New York City annually, which is $20 billion over 10 years, and the city doesn’t necessarily know how to spend that money even at today’s construction costs, let alone rational construction costs.
At least New York has an internal bank of enthusiasts at the MTA and at shadow agencies like the RPA who have ideas for how to spend this money. Smaller cities for the most part don’t. Does Cleveland have any idea what it would do with $5 billion over ten years for regionwide transit expansion? Does Tampa? The federal government has to play an educational role in giving regions sample zoning codes for TOD, network design guidelines, and procurement guidelines that help reduce costs.
Start planning now
A large infrastructure bill planned for 2021 has to be planned now. Its proponents do not intend for it to be a regular jobs program based on existing local wishlists: they intend for it to represent a shift in national priorities, which means that each item of spending has to be planned in advance, mostly from scratch. It means the political work of aligning various interest groups toward the same goal has to start early, which seems to be what the proponents are doing; even the name Green New Deal evokes progressive nostalgia for olden days before neoliberalism.
But alongside the political work, there must be good technical work. Regional planning agencies have to be aware this may be coming and have to have solid ideas for how they’d like to spend a few billion dollars over the decade. Simultaneously, organs including federal offices like the GAO, transit agencies, shadow agencies, and thinktanks have to learn and transmit a culture of good operating and capital practices. A government that plays a bigger role in the economy or in society has to become more competent; managerial competence is required for any program that allocates money with any precision, and very good cost control is a must to make sure the available budget goes to a green transition and isn’t wasted on red tape.
Six and a half years ago, the Federal Railroad Administration announced that it was going to revise its passenger train regulations. The old regulations required trains to be unusually heavy, wrecking the performance of nearly every piece of passenger rolling stock running in the United States. Even Canada was affected, as Transport Canada’s regulations mirrored those south of the border. The revision process came about for two reasons: first, the attempt to apply the old rules to the Acela trains created trains widely acknowledged to be lemons and hangar queens (only 16 out of 20 can operate at any given time; on the TGV the maximum uptime is 98%), and second, Caltrain commissioned studies that got it an FRA waiver, which showed that FRA regulations had practically no justification in terms of safety.
The new rules were supposed to be out in 2015, then 2016, then 2017. Then they got stuck in presidential administration turnover, in which, according to multiple second-hand sources, the incoming Republican administration did not know what to do with a new set of regulations that was judged to have negative cost to the industry as it would allow more and lower-cost equipment to run on US tracks. After this limbo, the new rules have finally been published.
What’s in the new regulations?
The document spells out the main point on pp. 13-20. The new rules are similar to the relevant Euronorm. There are still small changes to the seats, glazing, and emergency lighting, but not to the structure of the equipment. This means that unmodified European products will remain illegal on American tracks, unlike the situation in Canada, where the O-Train runs unmodified German trains using strict time separation from freight. However, trains manufactured for the needs of the American market using the same construction techniques already employed at the factories in France, Germany, Switzerland, and Sweden should not be a problem.
In contrast, the new rules are ignoring Japan. The FRA’s excuse is that high-speed trains in Japan run on completely dedicated tracks, without sharing them with slower trains. This is not completely true – the Mini-Shinkansen trains are built to the same standards as the Shinkansen, just slightly narrower to comply with the narrower clearances on the legacy lines, and then run through to legacy lines at lower speed. Moreover, the mainline legacy network in Japan is extremely safe, more so than the Western European mainline network.
On pp. 33-35, the document describes a commenter who most likely has read either my writings on FRA regulations or those of other people who made the same points in 2011-2, who asked for rules making it possible to import off-the-shelf equipment. The FRA response – that there is no true off-the-shelf equipment because trains are always made for a specific buyer – worries me. The response is strictly speaking true: with a handful of exceptions for piggybacks, including the O-Train, orders are always tailored to the buyer. However, in reality, this tailoring involves changes within certain parameters, such as train width, that differ greatly within Europe. Changes to parts that are uniform within Europe, such as the roofing, may lead to unforeseen complications. I don’t think the cost will be significant, but I can’t rule it out either, and I think the FRA should have been warier about this possibility.
The final worry is that the FRA states the cost of a high-speed train is $50 million, in the context of modification costs; these are stated to be $300,000 for a $50 million European high-speed trainset and $4.7 million for a Japanese one. The problem: European high-speed trainsets do not cost $50 million. They cost about $40 million. Japanese sets cost around $50 million, but that’s for a 16-car 400-meter trainsets, whereas European high-speed trainsets are almost always about 200 meters long, no matter how many cars they’re divided into. If the FRA is baking in cost premiums due to protectionism or bespoke orders, this is going to swamp the benefits of Euronorm-like regulations.
But cost concerns aside, the changes in the buff strength rules are an unmitigated good. The old rules require trainsets to resist 360-945 metric tons of force without deformation (360 for trains going up to 200 km/h, 945 beyond 200 km/h), which raises their mass by several tons per cars – and lightweight frames require even more extra mass. The new ones are based on crumple zones using a system called crash energy management (CEM), in which the train is allowed to deform as long as the deformation does not compromise the driver’s cab or the passenger-occupied interior, and this should not require extra train mass.
How does it affect procurement?
So far, the new rules, though telegraphed years in advance, have not affected procurement. With the exception of Caltrain, commuter railroads all over the country have kept ordering rolling stock compliant with the old rules. Even reformers have not paid much attention. In correspondence with Boston-area North-South Rail Link advocates I’ve had to keep insisting that schedules for an electrified MBTA must be done with modern single-level EMUs in mind rather than with Metro-North’s existing fleet, which weighs about 65 metric tons per car, more than 50% more than a FLIRT per unit of train length.
It’s too late for the LIRR to redo the M9, demanding it be as lightweight as it can be. However, New Jersey Transit’s MultiLevel III is still in the early stages, and the railroad should scrap everything and require alternate compliance in order to keep train mass (and procurement cost) under control.
Moreover, the MBTA needs new trains. If electrification happens, it will be because the existing fleet is so unreliable that it becomes attractive to buy a few EMUs to cover the Providence Line so that at least the worst-performing diesels can be retired. Under no circumstance should these trains be anything like Metro-North’s behemoths. The trains must be high-performance and as close as possible to unmodified 160 km/h single-level regional rail rolling stock, such as the DBAG Class 423, the Coradia Continental, the Talent II, or, yes, the FLIRT.
Metra is already finding itself in a bind. It enjoys its antediluvian gallery cars, splitting the difference between one and two decks in a way that combines the worst of both worlds; first-world manufacturers have moved on, and now Metra reportedly has difficulty finding anyone that will make new gallery cars. Instead, it too should aim at buying lightly modified European trains. These should be single-level and not bilevel, because bilevels take longer to unload, and Chicago’s CBD-dominant system is such that nearly all passengers would get off at one station, Millennium Station at the eastern edge of the Loop, where there are seven terminating tracks and (I believe) four approach tracks.
Ultimately, on electrified lines, the new rules permit trains that are around two thirds as heavy as the existing EMUs and have about the same power output. Substantial improvements in train speed are possible just from getting new equipment, even without taking into account procurement costs, maintenance costs, and electricity consumption. Despite its flaws, the new FRA regulation is positive for the industry and it’s imperative that passenger railroads adapt and buy better rolling stock.
I’ve sporadically discussed how some countries or regions have traditions of how to build rapid transit. For example, in a City Metric article last year I made an off-hand comment about how communist bloc metros, from Europe to North Korea, have widely-spaced stops just like Moscow, while French metros and French-influenced Montreal Metro have short stop spacing just like Paris. I intend to write some posts covering different traditions, starting from one I’ve barely discussed as such: the American one. There are commonalities to how different American cities that build subways choose to do so, usually with notable New York influences, and these in turn affect how American transit activists think about trains.
For the most part, the American tradition of rapid transit should be viewed as one more set of standards, with some aspects that are worth emulating and others that are not. Most of the problems I’ve harped on are a matter of implementation more than a matter of standards. That said, that something is the local tradition does not immediately mean it works, even if on the whole the tradition is not bad. Some of the traditions discussed below definitely increase construction costs or reduce system effectiveness.
The situation in New York
A large majority of American rapid transit ridership, about two thirds, is in New York. The city’s shadow is so long that the systems built in the postwar era, like the Washington Metro and BART, were designed with New York as a reference, whether consciously or not. Only the Boston subway and Chicago L are old enough to avoid its influence – but then their elevated system design still has strong parallels in New York, whether due to direct influence or a common zeitgeist at the end of the 19th century. Thus, the first stop on the train of thought of the American rapid transit tradition must be New York practice.
New York has nine subway main lines. Five are north-south through Manhattan and four-track, three are east-west and two-track, and one avoids Manhattan entirely. Nearly all construction was done cut-and-cover between 1900 and 1940, forcing lines to hew to the street network. As New York has wide, straight streets, a trait shared with practically all American cities, this was not a problem, unlike in London, where carving right-of-way for the Underground was so difficult that every line from the third onward was built deep-bore.
With four tracks on most of the Manhattan trunks, there is local and express service. This allows trains to go around obstacles more easily, increasing redundancy. It’s in this context that New York’s 24/7 service makes sense: there is no absolute need for nighttime maintenance windows in which no train runs. This approach works less well on the two-track lines, and the L, the only one that’s two-track the entire way, has occasional work orders with very low train frequency because of single-tracking.
Outside the core of the city as it was understood during construction, lines run elevated. The standard New York el is an all-steel structure, which reduces construction costs – the First Subway’s subway : el cost ratio was 4:1, whereas today the average is about 2.5:1 even though tunneling uses the more expensive boring technique – at the cost of creating a boombox so noisy that it’s impossible to have a conversation under the tracks while a train is passing. Moreover, splitting the difference between two and four tracks, the standard el has three tracks, which allows peak-direction express service (on the 2/5, 6, and 7) or more space for trains to get around obstacles (on the 1, 4, and N/W).
Because the els are so noisy, the city stopped building them in the 1920s. The lines built in the 1930s were all underground, with the exception of one viaduct over an industrial shipping channel.
Moreover, from the 1930s onward, stations got bigger, with full-length mezzanines (the older stations had no or short mezzanines). Track standards increased, leading to an impressive and expensive array of flying junctions, contrasting with the flat junctions that characterize some older construction like the Chicago L or some foreign examples like much of the London Underground.
Finally, while New York has nine separate subway colors, its number of named lines is far greater. The system comprises several tens of segments called lines, and each route combines different lines, with complex branching and recombination. The infrastructure was never built for discrete lines with transfers between them, but rather for everywhere-to-everywhere one-seat rides, and service choices today reinforce this, with several outer lines reverse-branching to an East Side and a West Side Manhattan trunk.
The desire for 24/7 service
I know of five urban rail networks with 24/7 service. One is the Copenhagen Metro, which is driverless and built with twin bores, making it easy for service to single-track at night for maintenance. The other four are American: the New York City Subway, PATH, PATCO, and the Chicago L. Moreover, the LIRR runs 24/7, which no other commuter rail system I know of does, even ones where an individual outlying station has comparable ridership to the entire LIRR.
The other systems have somewhat of a 24/7 envy. I’ve heard lay users and activists in Washington and the Bay Area complain that the Washington and BART shut down overnight; BART itself feels it has to justify itself to the users on this question. Right now, BART’s decision to temporarily add an hour to the nighttime shutdown window to speed up maintenance is controversial. People are complaining that service is being cut despite increases in funding. In Washington, the more professional activists understand why 24/7 service is unviable, but like BART feel like they have to explain themselves.
Local and express trains
New York is full of four-track mainlines, running both local and express trains. Chicago and Philadelphia have them as well on one line each. The other rapid transit networks in the US don’t, but like 24/7 service desire it. Washington has enough complaints about it that regular reader and Patreon supporter DW Rowlands had to write an article for Greater Greater Washington explaining why it would not be all that useful.
BART is the more interesting case. In any discussion of BART extensions, people bring up the fact that BART can’t skip stops – never mind that its stop spacing is extremely wide owing to its function as suburban rail. The average speed on BART is 57 km/h per the National Transit Database; the RER A, which is the express service here, averages around 50. At BART’s speed, the single longest express segment in New York not crossing water, the A/D between 125th and 59th Streets, would take 7 minutes; in fact it takes about 9. If anything, BART errs in having too few stations in Oakland and San Francisco.
On new-build systems, four tracks are understandable and desirable, provided the construction method is cut-and-cover, as it was in early-20th century America. The earliest subway lines built in New York had little cost premium over London and Paris even though the tunnels were twice as wide for twice as many tracks. However, cut-and-cover is no longer used in developed countries owing to its heavy impact on merchants and residents along the way; already during WW2, Chicago dug the tunnels for the Red and Blue Lines of the L using deep boring. A city that bores tunnels will find that four-track tunnels cost twice as much as two-track tunnels, so it might as well built two separate lines for better coverage.
The shadow of steel els
New York, Boston, Philadelphia, and Chicago all built all-steel els. While cheaper, these structures are so noisy that by the 1930s they became untenable even in far-out neighborhoods, like on the Queens Boulevard Line. New lines in New York were underground; existing els were removed, quickly in New York and more slowly in Boston.
The newer systems built in the US avoided els entirely. BART planned to build one in Berkeley, but community opposition led to a change to an underground alignment; unlike subsequent examples of NIMBYism, Berkeley was willing to pay the cost difference. When tunnels are infeasible due to cost, American rail networks prefer at-grade rights-of-way, especially freeway medians. Rail rights-of-way are popular where available, such as on the realigned Orange Line in Boston, but freeway medians are common where rail alignments don’t exist.
The next generation of American urban rail systems, unable to tunnel in city center, turned to light rail in order to keep things at-grade. Across the border, in Canada, Vancouver built els to cover gaps in the right-of-way that turned into the Expo Line, and then built concrete els on the Millennium Line and outer Canada Line to reinforce the system. These brutalist structures are imposing, but I’ve had conversations under the viaducts in Richmond, just as I have in Paris under the mixed concrete and steel structures or in Sunnyside next to New York’s one concrete el.
New York did not invent reverse-branching. London has had it since the 1860s, when most South London railways ran separate trains to the City (at Cannon Street, London Bridge, or Blackfriars) or the West End (at Victoria or Charing Cross), and multiple North London railways ran trains to their traditional terminals or to the North London Railway for service to Broad Street. Paris has had it since even earlier: the railways operating out of Gare Saint-Lazare and Gare Montparnasse merged in 1851 and treated the two stations as reverse-branches allowing cities farther west to access both the Right Bank and the Left Bank. In both cities, this situation makes it harder to run coherent regional rail – in London the railways are spending considerable resources on disentangling the lines to increase frequency to South London’s many branches, and in Paris the fact that Montparnasse and Saint-Lazare serve similar destinations frustrated plans to connect the two stations with an RER tunnel.
Where New York innovated is in copying this practice on rapid transit, starting with the Dual Contracts era. In Brooklyn, existing as well as new outlying lines could be routed to any number of new crossings to Manhattan; in the Bronx and Eastern Brooklyn, a desire to give branches service to both the West Side and East Side led to reverse-branching even on the numbered lines, which were built from scratch and did not involve older suburban railroads.
Reverse-branching spread across the United States. Boston had it until it removed the Atlantic Avenue El, and even today, railfans occasionally talk about reverse-branching the Red Line along Massachusetts Avenue to Back Bay and Roxbury. Chicago occasionally has it depending on the arrangement of trains on the North Side; today, the Purple and Brown Lines share tracks at rush hour but then go in opposite directions on the Loop. The Broad Street Line in Philadelphia reverse-branches to Chinatown. The Washington Metro has reverse-branches in Virginia, limiting train frequency due to asymmetry at the merge points. BART designed itself to force a three-way wye in Oakland pointing toward San Francisco, Berkeley and Downtown Oakland, and East Oakland on which every pair of destinations has a direct train, or else East Oakland residents would have to change trains to access their own city center – and current plans for a second trans-Bay tube add further reverse-branches instead of using the extra capacity as an opportunity to fix the Oakland junction.
Outside the United States, I know of four reverse-branches on rapid transit that is not historically regional rail: the Delhi Green Line, the Namboku and Mita Lines in Tokyo, the Yurakucho and Fukutoshin Lines also in Tokyo, and the Northern line’s two trunks in London. Of those, the last one is slowly being disentangled: its southern end will be two separate lines once the Battersea extension opens, and its northern end will, severing the line in two, once upgrades to pedestrian circulation are completed at the branch point. Historically Toronto had a three-way wye on the subway, like BART, but it caused so many problems it was discontinued in favor of running two separate lines.
The most prominent feature of American rail networks is not what they do, but what they lack. American (and Canadian, and Chinese) regional rail networks remain unmodernized, run for the exclusive benefit of upper middle-class suburban office workers at the primary CBD. Details differ between cities, but even when management is theoretically part of the same agency as the rapid transit network, as in Boston, New York, and Philadelphia, in practice the commuter railroads are autonomous. There is no hint of fare integration or schedule integration.
This fact influences network design more than anything else, even the low quality of steel els. Service to any destination beyond the dense urban core, which is small outside a handful of relatively dense cities, requires building new rail from scratch. This favors low-cost, low-capacity light rail, often in freeway medians. Smaller cities, unable to afford enough light rail to convince entire counties to tax themselves to build transit, downgrade service one step further and build bus rapid transit, typically treated as a weird hybrid of Latin American busways and European bus lanes.
Does any of this work?
In one word, no. The American tradition of rapid transit clearly doesn’t work – just look at the weak ridership even in old cities like Boston and Philadelphia, whose mode shares compare with medium-size urban regions in the French sunbelt like the Riviera or Toulouse.
Or, more precisely, it doesn’t work in early-21st century America. In the rare occasion an American city manages to round up funding to build a new subway line, I would recommend looking abroad for models of both construction methods and network design. For example, as BART keeps working on designing the second tube, I would strongly advise against new branches on the East Bay – instead, one of the two tubes (old and new) should permanently serve East Oakland, with a new Downtown Oakland transfer station, and the other should serve Berkeley and Concord.
Moreover, the United States owes it to itself to aggressively modernize its mainline passenger rail network. It’s too important to let Amtrak, the LIRR, Metro-North, Metra, and other dinosaurs do what they’ve always done. Toronto’s modernization of GO Transit, named the Toronto RER after the Western world’s premier regional rail network, had wide support among transit planners, but the engineers at GO itself were against it, and Metrolinx had to drag them into the 21st century.
Where the American tradition does work is in contexts that the United States has long left behind. Booming third-world cities direly need rapid transit, and while American construction costs are not to be emulated, the concept of opening up major throughfares, laying four tracks, and covering the system is sound. The mix of underground construction in city center and elevated construction farther out (using concrete structure, not louder steel ones) is sound as well, and is already seeing use in China and India. This is especially useful in cities that have little to no legacy regional rail, in which category India and China do not qualify, but most of the rest of the third world does.
Globalization makes for grand shuffles like this one. Experts in the United States should go to Nigeria, Bangladesh, Pakistan, Colombia, Kenya, Tanzania, Angola, and the Philippines and advise people in these countries’ major cities about how to emulate rapid transit designs from early-20th century America. But in their home country these same experts should instead step aside and let people with experience in the traditions of Japan, South Korea, and the various distinct countries of Western and Central Europe make decisions.
I did a Patreon poll last month with three options, all about development and transit: CBDs and job concentration in middle-income cities (e.g. auto-oriented Bangkok and Istanbul don’t have transit-oriented Shanghai’s CBD formation), dense auto-oriented city neighborhoods (e.g. North Tel Aviv), and transit-oriented low-density suburbia. This is the winning option.
In every (or almost every) city region, there’s a clear pattern to land use and transportation: the neighborhoods closer to the center have higher population density and lower car use than the ones farther away. Moreover, across city regions, there is such a strong negative correlation between weighted density and auto use that exceptions like Los Angeles are notable. That said, the extent of the dropoff in transit use as one moves outward into suburbia is not the same everywhere, and in particular there are suburbs with high transit use. This post will discuss which urban and transportation policies are likely to lead such suburbs to form, in lieu of the more typical auto-oriented suburbs.
What is a suburb?
Definitions of suburbia differ across regions. Here in Paris, anything outside the city’s 1860 limits is the suburbs. The stereotypical banlieue is in history, urban form, and distance from the center a regular city neighborhood that just happens to be outside the city proper for political reasons. It is hardly more appropriate to call any part of Seine-Saint-Denis a suburb than it is to call Cambridge, Massachusetts a suburb of Boston.
So if Seine-Saint-Denis is not a suburb, what is? When I think of suburbia, my prototype is postwar American white flight suburbs, but stripped of their socioeconomic context. The relevant characteristics are,
- Suburbs developed at a time when mass motorization was widespread. In the US, this means from around 1920 onward in the middle class and slightly later in the working class; in the rest of the developed world, the boundary ranges from the 1920s to the 1960s depending on how late they developed. Note that many stereotypical suburbs were founded earlier, going back even to the 19th century, but grew in the period in question. Brookline is famous for refusing annexation to Boston in 1873, but its fastest development happened between 1910 and 1930, straddling the 1920 limit – and indeed in other respects it’s borderline between a rich suburb and rich urban neighborhood as well.
- Suburbs have low population density, typical of single-family housing. Aulnay-sous-Bois, at 5,100 people per km^2, is too dense, but not by a large margin. Beverly Hills, which has mansions, has 2,300, and Levittown, New York, probably the single best-known prototype of a suburb, has 2,900. The urban typology can mix in apartments, but the headline density can’t be dominated by apartments, even missing middle.
- Suburbs are predominantly residential. They can have distinguished town centers, but as broad regions, they have to have a significant number of commuters working in the city. This rules out low-density central cities like Houston and Dallas (although their individual neighborhoods would qualify as suburbs!). It also rules out Silicon Valley as a region, which represents job sprawl more than residential sprawl.
The three criteria above make no mention of whether the area is included in the central city. Most of Staten Island qualifies as suburban despite being part of New York, but Newark fails all three criteria, and Seine-Saint-Denis and most of Hudson County fail the first two.
Where are suburbs transit-oriented?
I do not know of any place where suburban transit usage is higher than city center transit usage. In theory, this suggests that the best place to look for transit-oriented suburbia is the cities with the highest transit mode shares, such as Tokyo, Singapore, and Hong Kong (or, in Europe, Paris). But in reality, Singapore and Hong Kong don’t have areas meeting the density definition of suburb, and Tokyo has few, mostly located away from its vast commuter rail network. Paris has more true suburbs, but like Tokyo’s, they are not what drives the region’s high rail ridership. All four cities are excellent examples of high-density suburban land use – that is, places that meet my first and third definitions of suburbia but fail the second.
Instead, it’s better to look at smaller, lower-density cities. Stockholm and Zurich are both good models here. Even the central cities are not very dense, at 5,100 and 4,700 people per km^2. Moreover, both are surrounded by large expanses of low-density, mostly postwar suburbia.
Winterthur, Zurich’s largest suburb, is a mix of early 20th century and postwar urban typology, but the other major cities in the canton mostly developed after WW2. At the time, Switzerland was already a very rich country, and car ownership was affordable to the middle class. The story of the Zurich S-Bahn is not one of maintaining mode share through a habit of riding transit, but of running frequent commuter rail to suburbs that did not develop around it from the 1950s to the 70s.
In Stockholm, there is a prominent density gradient as one leaves Central Stockholm. I lived in Roslagstull, at the northern end of Central Stockholm, where the density is 30,000 people per km^2 and the built-up form is the euroblock. Most of the rest of Central Stockholm is similar in urban form and not much less dense. But once one steps outside the city’s old prewar core, density nosedives. City districts to the west and south, like Bromma and Älvsjö, go down to 3,000 people per km^2 or even a little less. A coworker who used to live in Kista described the area as American-style suburban. Beyond these city districts lie the other municipalities, which together form a sizable majority of the county’s population. Of those, a few (Solna, Sundbyberg) are somewhat above the density cutoff, but most are far below it.
In both Zurich and Stockholm, the city is much more transit-oriented than the suburbs. Stockholm’s congestion pricing was a city initiative; the suburbs banded together to oppose it, and eventually forced a compromise in which congestion pricing remained in effect but the revenue would be deeded to urban freeways rather than to public transportation.
And yet, neither city has a big transit use gradient – at least, not so big as Paris, let alone London or New York. Stockholm is expecting 170,000 daily metro trips from its expansion program, which barely touches Central Stockholm. Existing T-bana ridership on the suburban tails is pretty high as well (source, PDF-p. 13), as is ridership on commuter rail, which, too, barely touches Central Stockholm.
The structure of density
In my previous post, I complained that Los Angeles’s density has no structure, and thus public transit ridership is very low and consists predominantly of people too poor to buy a car. The situation in Stockholm and Zurich is the reverse. Density has a clear structure: within each suburb, there is a town center near the commuter rail station.
The histories of Zurich and Stockholm are profoundly different. Each arrived in its structure from a different route. In Zurich, the suburbs come from historic town centers that existed long before cars, often long before industrialization. 20th-century urban sprawl arrived in the form of making these historic villages bigger and bigger until they became proper suburbs. The geography helps rail-oriented suburbanization as well: the ridge-and-valley topography is such that urban sprawl forms ribbons served by commuter rail lines, especially in the southerly direction.
Stockholm’s topography is nothing like Zurich’s. There are water boundaries limiting suburb-to-suburb travel, but the same is true of New York, and yet Long Island, New Jersey, and Westchester are thoroughly auto-oriented. Instead, the structure of density came about because of government planning. Sweden built public housing simultaneously with the Stockholm Metro, so the housing projects were sited near the train stations.
This does not mean that the suburbs of Zurich and Stockholm are actually high-density. Far from it: the housing projects in the Stockholm suburbs are surrounded by a lot of parking and greenery, and the suburbs have extensive single-family housing tracts. However, the density is arranged to grade down from the train station, and there are small clusters of walkable apartment buildings in a small radius around each station. In Zurich the same structure came about with private construction and topography.
To the extent this structure exists elsewhere, it leads to higher low-density transit ridership too, for example in London and the Northeastern United States. Various West Coast American transit bloggers, like Jarrett Walker and Let’s Go LA, keep plugging the West Coast grid over the Northeastern hierarchy of density. But this hierarchy of suburbs that formed around commuter rail to the CBD produces transit ridership that, while awful by Continental European standards, is very good by American ones. Many of the suburbs in question, such as in Westchester, have 15-20% of their commuters choose transit to get to work.
Getting to higher numbers means reinforcing the structure of density and the transit that works in the suburbs, that is, regional rail (or a metro network that goes far out, like the T-bana, if that’s an option). Stations must be surrounded by development rather than parking, and this development should facilitate a somewhat transit-oriented lifestyle, including retail and not just housing. Jobs should be accessible from as many directions as possible, forming CBDs rather than haphazard town centers accessible only by road. Only this way can suburbia be transit-oriented.
Seven years ago, I wrote a pair of posts about Sunnyside Yards. The first recommends the construction of a transfer station through Sunnyside Yards, in order to facilitate transfers between Penn Station- and Grand Central-bound trains. The second recommends redeveloping the yards via a deck, creating high-density residential and commercial space on a deck on top of the yard. Recent news, both about an official plan to deck the yards and about leaks that Amazon is likely to move half of its second headquarters (HQ2) to Long Island City, make a Sunnyside Junction so much more urgent.
Here is how service would look:
The color scheme is inherited from my regional rail maps (see e.g. here) but for the purposes of this post, all it means is that green and blue correspond to the inner and outer tracks of the Park Avenue, purple is East Side Access, orange corresponds to LIRR trains going to the northern pair of East River Tunnels, and red corresponds to LIRR, Metro-North Penn Station Access, and Amtrak trains going to the southern pair of East River Tunnels. No track infrastructure is assumed except what’s already in service or funded (i.e. ESA and Penn Station Access), and only two infill stations are mapped: Astoria, which would be a strong location for a stop were fares integrated with the subway and frequency high, and Sunnyside Junction.
The infill stations that are not planned
An Astoria station was studied for PSA, but was dropped from consideration for two reasons. First, the location is legitimately constrained due to grades, though a station is still feasible. And second, under the operating assumptions of high fares and low off-peak frequency, few people would use it. It would be like Wakefield and Far Rockaway, two edge-of-city neighborhoods where commuter rail ridership is a footnote compared with slower but cheaper and more frequency subway service.
A Sunnyside Junction station was in contrast never considered. There are unfunded plan for an infill station to the west of the junction, served only by Penn Station-bound trains. Such a station would hit Long Island City’s job center well, but the walk from the platform to the office towers would still be on pedestrian-hostile roads, and if there’s political will to make that area more walkable, the city might as well just redevelop Sunnyside Yards (as already planned).
The reason there was never any plan for a station can be seen by zooming in on the area I drew as a station. It’s a railyard, without streets (yet). At today’s development pattern, nobody would use it as an O&D station, even if fares and schedules were integrated with the subway. The importance of the station is as a transfer point between Grand Central- and Penn Station-bound trains. The planned developments (both HQ2 and independent city plans) makes it more urgent, since the area is relatively far from the subway, but the main purpose of the station is a better transit network, rather than encouraging development.
The main benefit of the station is transfers between the LIRR and Metro-North. While nominally parts of the MTA, the two agencies are run as separate fiefs, both of which resisted an attempt at a merger. The LIRR opposed PSA on the grounds that it had a right to any empty slots in the East River Tunnels (of which there are around 8 per hour at the peak). Governor Cuomo intervened to protect PSA from Long Island’s opposition, but in such an environment, coordinated planning across the two railroads is unlikely, and the governor would not intervene to improve the details of the ESA and PSA projects.
East Side Access means that in a few years, LIRR trains will split between two Manhattan destinations. Conceptually, this is a reverse-branch: trains that run on the same route in the suburbs, such as the LIRR Main Line, would split into separate routes in the city core. In contrast, conventional branching has trains running together in the core and splitting farther out, e.g. to Oyster Bay, Port Jefferson, and Ronkonkoma. Reverse-branching is extremely common in New York on the subway, but is rare elsewhere, and leads to operational problems. London’s Northern line, one of the few examples of reverse-branching on an urban subway outside New York, is limited to 26 trains per hour through its busiest trunk at the peak, and long-term plans to segregate its two city trunks and eliminate reverse-branching would raise this to 36.
To ensure LIRR trains run with maximum efficiency, it’s necessary to prevent reverse-branching. This means that each trunk, such as the Main Line and the Hempstead Branch, should only ever go to one Manhattan terminal. Passengers who wish to go to the other Manhattan terminal should transfer cross-platform. Jamaica is very well-equipped for cross-platform transfers, but it’s at a branch point going to either Manhattan or Downtown Brooklyn, without a good Penn Station/Grand Central transfer. Without a good transfer, passengers would be stuck going to a terminal they may not work near, or else be forced into a long interchange. In London the reason the Northern line is not already segregated is that the branch point in the north, Camden Town, has constrained passageways, so eliminating reverse-branching requires spending money on improving circulation.
Unlike Camden Town, Sunnyside Junction is roomy enough for cross-platform transfers. The tracks should be set up in a way that LIRR trains going to East Side Access should interchange cross-platform with PSA and Port Washington Branch trains (which should go to Penn Station, not ESA), as they do not stop at Jamaica. Penn Station-bound LIRR trains not using the Port Washington Branch, colored orange on the map, should stop at Sunnyside too, but it’s less important to give them a cross-platform transfer.
This assignment would be good not just for LIRR passengers but also for PSA passengers. Unlike on the LIRR, on the New Haven Line, reverse-branching is unavoidable. However, passengers would still benefit from being able to get on a Penn Station-bound train and connecting to Grand Central at Sunnyside. Not least, passengers on the PSA infill stations in the city would have faster access to Grand Central than they have today via long walks or bus connections to the 6 train. But even in the suburbs, the interchange would provide higher effective frequency.
The connection with development
I don’t know to what extent decking Sunnyside Yards could attract Amazon. I wrote an article last year, which died in editing back-and-forth, lamenting that New York was unlikely to be the HQ2 site because there was no regional rail access to any of the plausible sites thanks to low frequency and no through-running. Long Island City’s sole regional rail access today consists of LIRR stations on a reverse-branch that does not even go into Manhattan (or Downtown Brooklyn) and only sees a few trains per day. It has better subway access and excellent airport access, though.
However, since Sunnyside Junction is so useful without any reference to new development, the plans for decking make it so much more urgent. Sunnyside Yards are in the open air today, and there is space for moving tracks and constructing the necessary platforms. The cost is likely to be in the nine figures because New York’s construction costs are high and American mainline rail construction costs are even higher, but it’s still a fraction of what it would take to do all of this under a deck.
Moreover, the yards are not easy to deck. Let’s Go LA discussed the problem of decking in 2014: columns for high-rise construction are optimally placed at intervals that don’t jive well with railyard clearances, and as a result, construction costs are a multiple of what they are on firma. Hudson Yards towers cost around $12,000/square meter to build, whereas non-WTC commercial skyscrapers in the city are $3,000-6,000 on firma. The connection with Sunnyside Junction is that preparing the site for the deck requires extensive reconfiguration of tracks and periodic shutdowns, so it’s most efficient to kill two birds with one stone and bundle the reconfiguration required for the station with that required for the deck.
In the other direction, the station would make the deck more economically feasible. The high construction costs of buildings on top of railyards makes decking unprofitable except in the most desirable areas. Even Hudson Yards, adjacent to Midtown Manhattan on top of a new subway station, is only treading water: the city had to give developers tax breaks to get them to build there. In Downtown Brooklyn, Atlantic Yards lost the developer money. Sunnyside Yards today are surrounded by auto shops, big box retail, and missing middle residential density, none of which screams “market rents are high enough to justify high construction costs.” A train station would at least offer very fast rail access to Midtown.
If the decking goes through despite unfavorable economics, making sure it’s bundled with a train station becomes urgent, then. Such a bundling would reduce the incremental cost of the station, which has substantial benefits for riders even independently of any development it might stimulate in Sunnyside.