Category: Good Transit

Fix the Slowest Speed Zones

I am wrapping up a project to look at speedup possibilities for trains between New York and New Haven; I’ll post a full account soon, but the headline result is that express trains can get between Grand Central and New Haven in a little more than an hour on legacy track. In this calculation I looked at speed zones imposed by the curves on the line. The biggest possible speedups involve speed limits that are not geometric – and those in turn come from some very sharp slow zones. The worst is the Grand Central station throat, and I want to discuss that in particular since fixing the slowest zones usually yields the most benefits for train travel times.

Best practice for terminal approaches

Following Richard Mlynarik’s attempt to rescue the Downtown Extension in San Francisco, I’ve assumed that trains can approach terminals at 70 km/h, based on German standards. At this speed, an EMU on level track can stop in about 150 meters. In Paris, the excellent Carto Metro site details speed limits, and at most terminals with bumper tracks the speed limit is 60 km/h, with a few going up to 100 km/h.

Even with bumper tracks, 70 km/h can be supported, provided the train is not intended to stop right at the bumpers. At a fixed speed, the deceleration distance is the inverse of the deceleration rate. There is some variation in braking performance, but it’s in a fairly narrow range; on subway trains in New York, everything is supposed to brake at the same nominal rate of 3 mph/s, or 1.3 m/s^2, and when trains brake more slowly it’s because of a deliberate decision to avoid wearing the brakes out. As long as the train stops 1-2 car lengths away from the bumpers, as is routine on Metro-North, the variation will be much smaller than the margin of safety.

Fast movement through the station throat is critical for several reasons. First, as I’ll explain below, sharp speed limits have an outsize effect on trip times, and can be fixed without expensive curve easements or top-rate rolling stock. And second, at train stations with a limited number of tracks, the station throat is the real limiting factor to capacity, since trains would be moving in and out frequently, and if they move too slowly, they’ll conflict. With its 60 km/h throat, Saint-Lazare on the RER E turns 16 trains per hour at the peak on only four tracks.

American practice

I had a conversation with other members of TransitMatters in Boston yesterday, in which we discussed work to be done for our regional rail project. One of the other members, I forget who, asked me, do European train protection systems shut down in station throats too?

The answer to the question is so obviously yes that I wanted to understand why anyone would ask it. Apparently, the American mandate for automatic train protection on all passenger rail lines, under the name positive train control, or PTC, is only at speeds higher than 10 miles per hour. At 10 mph or less train operators can drive the train by sight, and no signaling is required, which is why occasionally trains overrun the bumpers even on PTC-equipped lines if the driver has sleep apnea.

Without video, nobody could see the facial expressions I was making. I believe my exact words were “…What? No! What? What the hell?”.

The conversation was about South Station, but the same situation occurs at Grand Central. Right-of-way geometry is good for decent station approach speed – there is practically no limit at Grand Central except tunnel clearances, which should be good for 100 km/h, and at South Station the sharp curve into the station from the west is still good for around 70 km/h given enough superelevation.

The impact of slow zones near stations

Last year, I published code for figuring out acceleration penalties based on prescribed train characteristics. The relevant parameters for Metro-North’s M8 is initial acceleration = 0.9 m/s^2, power/weight = 12 kW/t. Both of these figures are about two-thirds as high as what modern European EMUs are capable of, but it turns out that at low speed it does not matter too much.

Right now the Grand Central throat has a 10 mph speed limit starting just north of 59th Street, just south of milepoint 1. The total travel time over this stretch is 6 minutes, a familiar slog to every regular Metro-North rider; overall, the schedule between Grand Central and Harlem-125th Street is 10 minutes northbound and 12-13 minutes southbound, the difference coming from schedule padding. The remaining 65 or so blocks are taken at 60 mph, nearly 100 km/h, and take around 4 minutes.

Now, let’s eliminate the slow zone. Let trains keep cruising at 100 km/h until they hit the closer-in parts of the throat, say the last kilometer, where the interlocking grows in complexity and upgrading the switches may be difficult; in the last kilometer, let trains run at 70 km/h. The total travel time in the last mile now shrinks to a minute, and the total travel time between Grand Central and Harlem shrinks to 5 minutes and change. Passengers have gained 5 minutes based on literally the last mile.

For the same reason, the Baltimore and Potomac Tunnel imposes a serious speed limit – currently 30 mph through the tunnel, lasting about 2 miles; removing this limit would cut 2-2.5 minutes from the trip time, less than Grand Central’s 5 because the speed limit isn’t as wretched.

The total travel time between New York and New Haven on Metro-North today is about 1:50 off-peak, on trains making all stops north of Stamford. My proposed schedule has trains making the same stops plus New Rochelle doing the trip in 1:23. Out of the 27-28 minutes saved, 5 come from the Grand Central throat, the others coming from higher speed limits on the rest of the route as well as reduced schedule padding; lifting the blanket 75 mph speed limit in Connecticut is only worth about 3 minutes on a train making all stops north of Stamford, and even on an express train it’s only worth about 6 minutes over a 73 kilometer stretch.

What matters for high-speed travel

High-speed rail programs like to boast about their top speeds. But in reality, the difference between a vanilla 300 km/h train and a top of the line 360 km/h only adds up to a minute every 30 kilometers, exclusive of acceleration time. Increasing top speed is still worth it on lines with long stretches of full-speed travel, such as the Tohoku Shinkansen, where there are plans to run trains at 360 over hundreds of kilometers once the connection to Hokkaido reaches Sapporo. However, ultimately, all this extra spending on electricity and noise abatement only yields a second-order improvement to trip times.

In contrast, the slow segments offer tremendous opportunity if they are fixed. The 10 mph limit in the immediate Penn Station throat slows trains down by around 2 minutes, and those of Grand Central and South Station slow trains by more. A 130 km/h slog through suburbia where 200 km/h is possible costs a minute for every 6.2 km, which easily adds up to 5 minutes in a large city region like Tokyo. An individual switch that imposes an undue speed limit can meaningfully slow the schedule, which is why the HSR networks of the world invented high-speed turnouts.

Richard Mlynarik notes that in Germany, the fastest single end-to-end intercity rail line used to be Berlin-Hamburg, a legacy line limited to 230 km/h, where trains averaged about 190 km/h when Berlin Hauptbahnhof opened (they’ve since been slowed and now average 160). Trains go at full speed for the entire way between Berlin and Hamburg, whereas slow urban approaches reduce the average speed of nominally 300 km/h Frankfurt-Cologne to about 180, and numerous compromises reduce that of the nominally 300 km/h Berlin-Munich line to 160; even today, trains from Berlin to Hamburg are a hair faster than trains to Munich because the Berlin-Hamburg line’s speed is more consistent.

The same logic applies to all travel, and not just high-speed rail. The most important part of a regional railway to speed up is the slowest station throats, followed by slow urban approaches if they prove to be a problem. The most important part of a subway to speed up is individual slow zones at stations or sharp curves that are not properly superelevated. The most important part of a bus trip to speed up is the most congested city center segment.

The Rhine-Neckar Region

The weekend before last, I visited Kaiserslautern and Mainz; I have photos from Mainz and will blog about it separately later this week. Due to a train cancellation, my 2.5-hour direct train to Kaiserslautern was replaced with a three-leg itinerary via Karlsruhe and Neustadt that took 5.5 hours. Even though neither Kaiserslautern nor Karlsruhe is contained within the region, they are both served by the Rhine-Neckar regional rail network. After riding the trains I looked up the network, and want to explain how things work in a metro area that is not very well-known for how big it is.

How polycentric is the system?

The Rhine-Neckar is polycentric, but only to a limited extent. It does have a single central city in Mannheim, with 300,000 people, plus another 170,000 in Ludwigshafen, a suburb across the Rhine. With Heidelberg (which has 160,000 people) and many surrounding suburbs, the total population of this region is 2.5 million, about comparable to Stockholm, Copenhagen, and Hamburg.

The liminal polycentricity comes from the fact that Mannheim has a distinguished position that no single central city has in the Ruhr or Randstad. However, Heidelberg, Neustadt, Worms, and Speyer are all independent cities, all of which have long histories. It’s not like Paris, where the suburbs were all founded explicitly as new towns – Versailles in the Early Modern era, and the rest (Cergy, La Defense, Evry, Marne-la-Vallee, etc.) in the postwar era.

The rail network has the same liminal characteristic, which is what makes it so interesting. There is an S-Bahn, centered on Mannheim. There are two main trunk lines, S1/2 and S3/4: every numbered line runs on an hourly clockface schedule, and S2 and S4 provide short-turn overlays on the S1 and S3 lines respectively, giving half-hourly service on the combined lines. Some additional lines are not Mannheim-centered: the S33 is circumferential, and the S5/51 are two branches terminating at Heidelberg. Additional lines fanning out of Mannheim are under construction, to be transferred from the RegionalBahn system; already S6 to Mainz is running every half hour, and there are plans for lines going up to S9.

However, it is wrong to view the Rhine-Neckar regional rail network as a Mannheim-centric system the way the RER is Paris-centric and the Berlin S-Bahn is Berlin-centric. The Mannheim-centered S-Bahn lines run alongside a large slew of legacy RegionalBahn lines, which run on hourly clockface schedules. The S3 serves Karlsruhe and the S1 and S2 serve Kaiserslautern, but this is not how I got from Karlsruhe to Kaiserslautern: I took a regional train via Neustadt, running on a more direct route with fewer stops via Wörth and Landau, and transferred to the S1 at Neustadt.

Integrated timed transfers

Kaiserslautern is not really part of the Rhine-Neckar region. It is too far west. However, it is amply connected to the core of the region: it has S1 and S2 rail service (in fact it is the western terminus of the S2), and it has regional trains to Mannheim as well as to other cities within the region. The regional train from Mannheim to Kaiserslautern and points west is timed to leave Neustadt a few minutes ahead of the S1, as it runs on the same line but makes fewer stops.

In addition, all these trains to cities of varying levels of importance have a system of timed transfers. I took this photo while waiting for my delayed train back to Paris:

Other than the S-Bahn east, the trains all leave a few minutes after 8:30, and I saw them all arrive at the station just before 8:30, allowing passengers to interchange across as well as between platforms. Judging by static arrival boards posted at stations, this integrated timed transfer repeats hourly.

Some of the lines depicted on the map serve cities of reasonable size, including Mannheim and Heidelberg, but also Homburg, the western terminus of the S1. Others don’t; Pirmasens is a town of 40,000, and the intermediate towns on the line as it winds through the Palatinate valleys have a few thousand people each. Nonetheless, there is evidently enough demand to run service and participate in the integrated timed transfer plan.

Population density and the scope of the network

As I’ve mentioned above, neither Kaiserslautern nor Karlsruhe is properly part of the Rhine-Neckar. Neither is Mainz, which is within the Frankfurt region. Nonetheless, all are on the Rhine-Neckar S-Bahn, and Kaiserslautern isn’t even an outer terminus – it’s on the way to Homburg.

This is for two reasons. The first is that this is a new S-Bahn network, cobbled together from regional lines that were formally transferred to the S-Bahn for planning purposes. It lacks the features that bigger S-Bahn networks have, like strong urban service. The Rhine-Neckar is about the same size as Hamburg, where the S-Bahn provides 10-minute frequencies to a variety of urban neighborhoods; in contrast, the S1/2 and S3/4 trunk lines in Mannheim aren’t even set up to overlay to exact 15-minute frequencies on the shared segment to Heidelberg.

I’ve talked about the distinction between regional and intercity service in the context of Boston. In Boston I recommend that some lines be run primarily as intercities, with long-range service and fewer stops, such as the Providence and Lowell Lines, both serving independent urban centers with weak inner suburbs on the way, while others be run primarily as locals, with more urban stops, such as the Fairmount-Franklin Line, which has no strong outer anchor but does pass through dense neighborhoods and inner suburbs.

The same distinction can be seen in Germany, all falling under the S-Bahn rubric. Wikipedia has a map of all S-Bahn systems in Germany at once: it can be readily seen that Hamburg, Berlin, Munich, Stuttgart, and Frankfurt have predominantly local systems, while Hannover, Nuremberg, the Rhine-Neckar, and Middle Germany (where the largest city is Leipzig) have predominantly intercity systems that are run as if they were S-Bahns.

The second reason owes to the urban geography of the Rhineland. Paris, Berlin, and Hamburg are all clearly-defined city centers surrounded by rings of suburbs. The Rhineland instead has a variety of smaller urban centers, in which suburb formation often takes the form of people hopping to a nearby independent city and commuting from there. All of these cities have very small contiguous built-up areas relative to the size of their metropolitan regions, and contiguous suburbs like Ludwigshafen are the exception rather than the rule.

Moreover, the background population density in the Rhineland is very high, so the cities are spaced very close together. This enabled the Rhine-Ruhr to form as a polycentric metro area comparable in size to London and Paris without having any core even approaching the importance of Central London or central Paris. The Upper Rhine is not as industrialized as the Ruhr, but has the same interconnected network of cities, stretching from Frankfurt and Wiesbaden up to Karlsruhe. In such a region, it’s unavoidable that commuter lines serving different urban cores will touch, forcing an everywhere-to-everywhere network.

To reinforce the importance of high density, we can look at other areas of high population density. The Netherlands is one obvious example, underlying Randstad and an extremely dense national rail network in which it’s not really possible to separate different regions for planning purposes. England overall is dense as well, but the south is entirely London-centric; however, the same interconnected network of cities typical of the Middle and Upper Rhine exists in Northern England, which not only invented the railway but also maintains a fairly dense rail network and has a variety of connecting services like TransPennine. Finally, the Northeastern United States has commuter rail line on nearly the entire length of the Northeast Corridor, touching in Trenton between New York and Philadelphia, with perennial plans to extend services in Maryland, Connecticut, and Rhode Island to close the remaining gaps.

Swiss lessons

Switzerland has long had a national integrated transfer timetable, overlaying more local S-Bahn trains in the biggest cities. As long as there is more than one node in such a network, it is necessary to ensure travel times between nodes permit trains to make multiple transfers.

This leads to the Swiss slogan, run trains as fast as necessary, not as fast as possible. This means that, in a system based on hourly clockface schedules, the trip times between nodes should be about an hour minus a few minutes to allow for transfer time and schedule recovery. Potentially it’s possible to set up some intermediate nodes to have transfers at half-integer hours rather than integer hours, allowing half-integer hour timed transfers. Switzerland’s main intercity lines run on a half-hourly takt, with timed transfers on the hour every half hour in Zurich, Bern, and Basel, which are connected in a triangle with express trains taking about 53 minutes per leg; additionally, some smaller cities have timed transfers 15 and 45 minutes after the hour.

Germany’s rail network is less modern than Switzerland’s, and the Rhine-Neckar schedule shows it. S-Bahn trains run between Kaiserslautern and Mannheim in a few minutes more than an hour, which is why the S-Bahn train depicted in the photo above does not participate in the hourly pulse. In contrast, the regional express trains take 45 minutes, which allows them to participate in the pulse with a little bit of wasted time at Mannheim. Potentially, the region may want to level these two service patterns into one local pattern with a one-way trip time of about 50 minutes, through speeding up the trains if possible. A speedup would not be easy – the rolling stock is already very powerful, and the line is 64 km and has 16 stations and a curvy western half. Discontinuing service on the S2 to two neighborhood stations in Ludwigshafen, which the S1 already skips, is most likely required for such a hybrid S-Bahn/RegionalExpress service.

However, it’s critical to stress that, while Germany is lagging Switzerland, Austria, the Netherlands, and Sweden, it is not to be treated as some American basket case. The Rhine-Neckar rail network is imperfect and it’s useful to understand how it can improve by learning from comparable examples, but it’s good enough so as to be a model for other systems in polycentric regions, such as New England, the Lehigh Valley, Northern England, and Nord-Pas-de-Calais.

The Soviet Bloc Way of Building Rapid Transit

Based on positive feedback from Patreon backers, I am expanding my post about the American way of building rapid transit into a series covering various national traditions. The Soviet bloc’s tradition is the most globally widespread, as Soviet advisors trained engineers in the USSR’s entire sphere of influence, ranging from just east of the Iron Curtain to North Korea. It is especially fascinating as it evolved independently of Western and Japanese metro-building traditions, from its origins in Moscow in the 1930s.

Like the American tradition, the Soviet tradition has aspects that are worth emulating and ones that are not. But it’s useful to understand where the design aspects come from. It’s especially interesting as Moscow has influences from London, so comparing where the Russians did better and where they did worse is a good case study of adapting a foreign idea to a different national context. Similarly, China imported Russian ideas of how to build metro networks while making considerable adaptations of its own, and I hope to cover China more fully in a future post, discussing there too how the tradition changed in the transmission.

Technical characteristics

The Soviet way is characterized by four major features:

Wide station spacing: the average interstations on the systems in question are all long. Moscow’s is 1.7 km, and for the most part cities in the former USSR with metros have similar interstations; in this table, length is in the row labeled 1 and number of stations in the row labeled 3. This is also true of the metro systems in China and North Korea, but in the Eastern European satellite states it’s less true, with Prague and the newer lines in Budapest averaging not much more than 1 km between stations.

Very little branching: Soviet lines do not branch, with a small handful of exceptions. Moscow’s only branching line, Line 4, is unique in multiple ways, as it was redesigned with American influence after Nikita Khrushchev’s visit to the United States. Eastern European satellite state metros do not branch, either, in contrast with contemporary postwar Western European networks like those of Stockholm and Milan. China has more branching, albeit less than Western and Japanese systems of comparable scope.

Radial network design: what I call the Soviet triangle, while not really a Soviet invention (it has antecedents in Boston and London), became a rigid system of network design in the communist bloc. Subway lines all run as rough diameters through the disk of the built-up area, and meet in the center in a triangle rather than in a three-way intersection in order to spread the load. Moscow adds a single circular line to the mix for circumferential travel, subsequently refined by a second and soon a third ring. Here, China diverges significantly, in that Beijing has grid elements like parallel lines.

Deep boring: Soviet and Soviet-influenced metro networks run deep underground. Traditionally, there was limited above-ground construction, for reasons of civil defense; in Moscow, only Line 4 is shallow, again due to American influence.

London’s long shadow

The decision to deep-bore the Moscow Metro was undertaken in the 1920s and 30s, long before the Cold War and the militarization of Soviet society. It even predates the turn to autarky under Stalin; as Branko Milanovic notes, the USSR spent most of the 1920s trying to obtain foreign loans to rebuild after the Revolution, and only when foreign capital was not forthcoming did it turn to autarky. The NKVD arrested the British advisors, conducted show trials, and deported them for espionage in 1933; the basic technical characteristics were already set then.

In London, the reason for deep boring is that the city has one street wide and straight enough for a cut-and-cover subway, Euston Road hosting the Metropolitan line. In Moscow, such streets are abundant. British planners were exporting both the idea of constructing wide throughfares based on modernist planning principles and that of deep-boring metro lines, an invention based on the context of a city that lacks such throughfares.

The network design bears similarity to what London would have liked to be. London is not as cleanly radial as Moscow, but it clearly tries to be radial, unlike New York or Paris. In general, it’s best to think of the early Moscow Metro as like early-20th century London Underground lines but cleaner – stations spaced farther apart, more regular radial structure, none of the little quirks that London’s had to build around like the Piccadilly line’s since-closed Aldwych branch.

Transit and socialism

The Soviet method of building metros may have originated in British planning, but its implementation throughout the 20th century was under socialist states, in which there was extensive central planning of the entire economy. Decisions regarding who got to live in the cities, where factories were to be sited, what goods were to be produced, and which sectors each city would specialize in were undertaken by the state.

There are several consequences of this political situation. First, by definition all urban development was social housing and all of it was TOD. Housing projects were placed regularly in ever-expanding rings around city center, where all the jobs were. There was no redevelopment, and thus density actually increased going out, while industrial jobs stayed within central cities even though in the capitalist bloc they suburbanized early, as factories are land-intensive.

Of note, some of this central planning also existed under social democracy: Sweden built the Million Program housing in Stockholm County on top of metro stations, creating a structure of density enabling high transit ridership.

But a second aspect is unique to proper communism: there were virtually no cars. Socialist central planning prioritized capital goods over consumer goods, and the dearth of the latter was well-known in the Cold War. At the same time, modernist city planning built very large roads. With no cars to induce people to fight for livable streets nor anything like the Western and Japanese New Left, urban design remained what today we can recognize as extremely car-oriented, before there were any cars. Major Eastern European cities are thus strongly bifurcated, between ones where a centrally planned metro has ensured very high per capita ridership, like Prague, Budapest, and Moscow (and also Bratislava, with trams), and ones where as soon as communism fell and people could buy cars the tramway network’s ridership cratered, like Tallinn, Riga, and I believe Vilnius.

The third and last aspect is that with extensive central planning, the seams that are visible in cities with a history of competition between different transit operators are generally absent. The incompatible gauges of Tokyo and the missed connections of New York (mostly built by the public-sector IND in competition with the private-sector IRT and BMT) do not exist in Moscow; Moscow does have missed connections between metro lines, but not many, and those are an awkward legacy of long interstations.

Of note, the autocratic aspects of socialism do not come into play in Soviet metro design. One would think that the Stalinist state would be able to engage in projects that in democracies are often unpopular due to NIMBYism, such as cut-and-cover subways, but the USSR did not pursue them. China does build elevated metro lines outside city centers, but evidently its plans to extend the Shanghai Maglev Train ran into local NIMBYism. People complained that the separation between the tracks and adjacent buildings was much less than in the German Transrapid standards; the Chinese state’s credibility on environmental matters is so low that people also trafficked in specious concerns about radiation poisoning.

The role of regional rail

The European socialist states all inherited the infrastructure of middle-income countries with extensive proto-industry – in particular, mainline rail. Russia had even completed the Trans-Siberian Railway before WW1. The bigger cities inherited large legacy commuter rail networks, where they operate commuter EMUs.

But while there are many regional trains in the European part of the former Soviet bloc, they are not S-Bahns. There was and still is no through-service, or frequent off-peak service. Connections between the metro and mainline rail were weak: only in 2016 did Moscow start using a circular legacy railway as its second urban rail ring.

The situation is changing, and just as Moscow inaugurated the Central Circle, so is it planning to begin through-service on radial commuter rail, called the Moscow Central Diameters. However, this is early 21st century planning, based on Western European rapid transit traditions.

Does this work?

In the larger cities, the answer is unambiguously yes: they have high transit ridership even when the population is wealthy enough to afford cars. The smaller cities are more auto-oriented, but that’s hardly the fault of Soviet metro planning when these cities don’t have metro networks to begin with; the fault there concerns urban planning more than anything.

Three aspects of Soviet metro planning deserve especial positive mention. The clean radial structure best approximates how single-core cities work, and Moscow and the cities it inspired deserve credit for not wasting money on low-ridership tangential lines, unlike Mexico City or (at smaller scale) Paris. It’s not too surprising that the Soviet triangle in particular exists outside the Soviet bloc, if not as regularly as in Eastern Europe.

The second positive aspect is the use of headway management in Moscow. With no branching and high frequency, Moscow Metro lines do not need to run on a timetable. Instead, they run on pure headway management: clocks at every station count the time elapsed since the last train arrived, and drivers speed up or slow down depending on what these clocks show relative to the scheduled headway between trains. At the peak, some lines run 39 trains per hour, the highest frequency I am aware of on lines that are not driverless (driverless metro technology is capable of 48 trains per hour, at least in theory, and runs 42 in practice on M14 in Paris).

The third and last is the importance of central planning. All public transportation in a metro region should be planned by a single organ, which should also interface with housing planners to ensure there is ample TOD. If anything, one of the bigger failures of Soviet metro planning is that it did not take this concept all the way, neither integrating metros with regional rail nor building a finger plan.

In contrast with these three positive aspects, station design is lacking. As frequent commenter and Patreon supporter Alexander Rapp noted in comments, there are some cross-platform transfers in Moscow; however, the initial three lines do not have such transfers, and instead the transfers became congested early, creating the impetus for the Circle Line. The deep-bored stations are expensive: Line 4 was built cut-and-cover to save money, not out of some cultural cringe toward New York, and today Russia is looking at cut-and-cover stations as a way to reduce construction costs.

Moreover, the wide interstations are too clean. The Underground has long interstations outside Central London and short ones within Central London, facilitating interchanges; while London has eight missed connections, these result from seams on lines running alongside each other or on branches, and only one pair of trunks has no transfer at all, the Metropolitan line and the Charing Cross half of the Northern line. In contrast, the relentlessly long interstations in Moscow lead to more misses.

Cross-Platform Transfers

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 Red-Blue Connector and the Importance of Connectivity

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.

Difficult Urban Geography Part 1: Narrow Streets

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:

Deep-bore tunneling

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.

Surface transit

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.

Single-track streetcars

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.

Urban Transit Vs. Commuter Transit

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.

In-Motion Charging

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.

Green New Deal

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.

FRA Reform is Here!

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.