# Why We Adjust Costs for PPP

The Transit Costs Project adjusts all construction costs for purchasing power parities. This means that, for example, a Chinese subway is converted into dollars not at the exchange rate of $1 = 6.7¥, but at the PPP rate of$1 = 4.2¥; this means that present-day Chinese subways look 1.5 times more expensive in our analysis than in analyses that use exchange rate values, and projects from 10 years ago look twice as expensive. I believe our choice is correct, and would like to explain why, since it has gotten some criticism from serious people, who’s prefer exchange rates.

Local costs

I started this comparing mature developed countries. The US and Europe have largely separate markets for construction, and so American work is almost entirely done in dollars and European work in euros (or pounds, or kronor, etc.). Japan is likewise very local and so is China. In that case, local costs matter far more than international ones.

But what’s interesting is that even in countries that use imported technology and international consultants and contractors and have low wages, costs are almost entirely local. I wrote about this last year, referencing an article out of India about the small cost impact of indigenization and an interview I made with a Philippine planner who told me 90% of the value of civil works is local. Rolling stock is internationally traded, but we exclude it from our cost estimates whenever possible.

The impact of currency changes

Using PPPs, if a country undergoes a bout of inflation, this should be reflected in changes in construction costs. This is intentional. The example given to me in the critique linked in the lede is that if Bangladeshi food prices rise, then this makes the PPP exchange rate look less favorable (a taka in Bangladesh can then buy less relative to a dollar in the US). But that’s fine – if Bangladeshi food prices rise then this forces Dhaka to pay higher wages to MRT construction workers, so overall it’s just domestic inflation. It’s no different from how, today, we’re seeing nominal construction cost growth in the United States and Europe because of high inflation.

At least the inflation today is moderate by any developing-country standard. Core inflation in the United States is 6%; in Germany it’s 3%. This may introduce third-order errors into the database as we deflate costs to the midpoint of construction. In contrast, 50-60% annual inflation is sustained over years in some middle-income countries like Iran, and then the choice of year for prices has significant impact, to the point that Iranian costs have a significant error bar. But that’s regardless of whether one adjusts for PPP or not, since usually inflation leads to deteriorating terms of trade.

In contrast, if prices are compared in exchange rate terms, then international fluctuations create fictitious changes in construction costs. When China permitted the renminbi to appreciate in the mid-2000s, this would have looked like an increase in costs of about 20% – but the costs of local inputs did not change, so in reality there was no increase in costs. The euro:dollar rate peaked around 1€ = $1.58 in 2008, before tumbling to 1€ =$1.28 in the financial crisis – but nothing material happened that would reduce European construction costs by 19% relative to American ones; right now it’s trading at 1€ = $1.05, but this again does not mean that construction in Europe is suddenly a third cheaper compared with in the US relative to 15 years ago. Unusual currency values Some patterns are systemic – richer countries have stronger currencies relative to PPP value than poor countries. But others are not, and it’s important to control for them. A currency can be weak due to the risk of war or disaster; the Taiwanese dollar is unusually weak for how rich Taiwan is, and this should not mean that Taiwanese construction costs are half what they really are. Or it can be strong or weak based on long-term investment proposition: investors will bid up the value of a currency in a country they expect to profit in in the long term, perhaps due to population growth coming from high birthrates or immigration, and this does not mean that today, it builds infrastructure more expensively. In any of those cases, the unusual value of the currency really reflects capital availability. Capital for investment in Australia is plentiful, but this by itself does not raise its construction costs; capital for investment in Taiwan is scarce, but this certainly does not make it a cheap place to build infrastructure. Foreign-denominated construction In some peripheral countries with unstable currencies, costs are quoted in foreign currency – dollars or euros. Some Turkish contracts are so quoted, and this is also common in Latin America and sometimes Southeast Asia. But ultimately, the vast majority of the contract’s value is paid out in the local currency, not just labor but also locally-made materials like concrete. This creates a weird-looking statistical artifact in which we convert dollars or euros to local currency in exchange rate terms and then back in PPP terms. This, we do because the quotation of the contract (in dollars or euros) is not the real value. Rather, it comes out of one of two artifacts. The first is data reporting: we rely on international trade media, and those often quote prices in exchange rate dollars or euros, even if the contract is in local currency (and in all cases where we’ve seen both, they match in exchange rate value). The second is that an international consultancy may demand actual payment in foreign currency as a hedge against currency depreciation; in that case its rate of profit should be dollar- or euro-denominated. However, this again is a small minority of overall contract value. Moreover, if a country’s institutions can’t produce enough capital stability to do business in their own currency, it’s a problem that should be reflected in global indices; ultimately, if costs are higher in PPP terms as a result, this means that the country really does have greater problem affording infrastructure. A posteriori justification The above reasoning is all a priori. When I started comparing costs in the early 2010s, I was comparing developed countries and the euro:dollar rate was in flux in the early financial crisis, so I just went with one long-term PPP rate. However, a posteriori, there is another positive feature of PPP adjustment: it levels the differences in construction costs by income. There is positive correlation between metro cost per km and the GDP per capita of the country the metro is built in, about 0.22, but it comes entirely out of the fact that poorer countries (especially India) build more elevated and fewer subway lines; correcting for this factor, the correlation vanishes. This is as it should be: PPP is a way of averaging out costs in different countries, first because it levels short-term fluctuations such as between different developed countries, and second because exchange rate value is dominated by internationally tradable goods, which are relatively more expensive in poor countries than non-tradable goods like food and housing. What this says is that infrastructure should be viewed as an average-tradable good, at least a posteriori: its variation in costs across the world is such that there is no correlation with GDP per capita, whereas food prices display positive correlation even after PPP adjustment, and tradables like smartphones display negative correlation (because they cost largely the same in exchange rate terms). # Tails on Commuter Rail An interesting discussion on Twitter came out of an alternatives analysis for Philadelphia commuter rail improvements. I don’t want to discuss the issue at hand for now (namely, forced transfers), but the discussion of Philadelphia leads to a broader question about tails. Commuter rail systems sometimes have low-frequency tails with through-service to the core system and sometimes don’t, and it’s useful to understand both approaches. What is a tail? For the purposes of this post, a tail is whenever there is a frequent line with trains infrequently continuing farther out. Frequency here is relative, so a subway line running every 2.5 minutes to a destination with every fourth train continuing onward is a tail even though the tail still has 10-minute frequency, and a commuter line running every 20 minutes with every third train continuing onward also has a tail, even though in the latter case the core frequency is lower than the tail frequency in the former case. The key here is that the line serves two markets, one high-intensity and frequent and one lower-intensity warranting less service, with the outer travel market running through to the inner one. Usually the implication is that the inner segment can survive on its own and the contribution of the outer segment to ridership is not significant by itself. In contrast, it’s common enough on S-Bahn systems to have a very frequent trunk (as in Berlin, or Munich, or Paris) that fundamentally depends on through-service from many suburban segments farther out combining to support high frequency in the core; if ridership farther out is significant enough that without it frequency in the core would suffer, I would not call this a tail. When are tails useful? Tails are useful whenever there is a core line that happens to be along the same route as a lower-intensity suburban line. In that case, the suburban line behind can benefit from the strong service in the core by having direct through-service to it at a frequency that’s probably higher than it could support by itself. This is especially valuable as the ridership of the tail grows in proportion to that of the core segment – in the limiting case, it’s not even a tail, just outer branches that combine to support strong core frequency. Tokyo makes extensive use of tails. The JR East commuter lines all have putative natural ends within the urban area. For example, most Chuo Rapid Line trains turn at Takao, at the western end of the built-up area of Tokyo – but some continue onward to the west, running as regional trains to Otsuki or as interregional or as intercity trains farther west to Shiojiri. Munich and Zurich both use tails as well on their S-Bahns. In Munich, the base frequency of each of the seven main services is every 20 minutes, but some have tails running hourly, and all have tails running two trains per hour with awkward alternation of 20- and 40-minute gaps. In Zurich, the system is more complex, and some lines have tails (for example, S4) and some do not (for example, S3); S4 is not a portion of an intercity line the way the Chuo Line is, and yet its terminus only gets hourly trains, while most of the line gets a train every 20 minutes. What are the drawbacks of tails? A tail is a commitment to running similar service as in the core, just at lower frequency. In Philadelphia, the proposal to avoid tails and instead force what would be tails into off-peak shuttle trains with timed transfers to the core system is bundled into separate brands for inner and outer service and a desire to keep the outer stations underbuilt, without accessibility or high platforms. Branding is an exercise in futility in this context, but there are, in other places than Philadelphia, legitimate reasons to avoid tails, as in Paris and Berlin: • Different construction standards – perhaps the core is electrified and an outer segment is not; historically, this was the reason Philadelphia ended commuter rail service past the limit of electrification, becoming the only all-electrified American commuter rail network. In Berlin, the electrification standards on the mainline and on the S-Bahn differ as the S-Bahn was electrified decades earlier and is run as an almost entirely self-contained system. • Train size difference – sometimes the gap in demand is such that the tail needs not just lower frequency than the core but also shorter trains. In the United States, Trenton is a good example of this – New York-Trenton is a much higher-demand line than Trenton-Philadelphia and runs longer trains, which is one reason commuter trains do not run through. • Extra tracks – if there are express tracks on the core segment, then it may be desirable to run a tail express, if it is part of an intercity line like the Chuo Line rather than an isolated regional line like S4 in Zurich, and not have it interface with the core commuter line at all to avoid timetabling complications. If there are no extra tracks, then the tail would have to terminate at the connection point with the core line, as is proposed in Philadelphia, and the forced transfer is a drawback that generally justifies running the tail. Do the drawbacks justify curtailment? Not really. On two-track lines, it’s useful to provide service into city center from the entire line, just maybe not at high frequency on outer segments. This can create situations in which intercity-scale lines run as commuter rail lines that keep going farther than typical, and this is fine – the JR East lines do this on their rapid track pairs and within the built-up area of Tokyo people use those longer-range trains in the same way they would an ordinary rapid commuter train. This is especially important to understand in the United States, which is poor in four-track approaches of the kind that the largest European cities have. I think both Paris and Berlin should be incorporating their regional lines into the core RER and S-Bahn as tails, but they make it work without this by running those trains on dedicated tracks shared with intercity service but not commuter rail. Boston, New York, and Philadelphia do not have this ability, because they lack the ability to segregate S-Bahn and RegionalBahn services. This means Boston should be running trains to Cape Cod, Manchester, and Springfield as tails of the core system, and New York should electrify its entire system and run trains to the Hamptons as LIRR tails, and Philadelphia should run tail trains to the entire reach of its commuter rail system. # Quick Note: How to Incentivize Transit-Oriented Development The Biden administration recently put out a statement saying that it would work to increase national housing production. It talks about the need to close the housing shortfall, estimated at 1.5 million dwellings, and proposes to use the Bipartisan Infrastructure Law (BIL) to dole out transport funding based on housing production. This is a welcome development, and I’d like to offer some guidelines for how this can be done most effectively. Incentives mean mistrust You do not need to give incentives to trustworthy people. The notion of incentives already assumes that the people who are so governed would behave poorly by themselves, and that the governing body, in this case the federal government, surveils them loosely so as to judge them by visible metrics set in advance. Once this fundamental fact is accepted – the use of BIL funding to encourage housing production implies mistrust of all local government to build housing – every other detail should be set up in support of it. Demand conflict with community Federal funding should, in all cases, require state and local governments to discipline community groups that fight housing and extract surplus from infrastructure. Regions that cannot or do not do so should receive less funding; the feds should communicate this in advance, stating both the principle and the rules by which it will be judged. For example, a history of surrender to local NIMBYs to avoid lawsuits, or else an unwillingness to fight said lawsuits, should make a region less favored for funds, since it’s showing that they will be wasted. In contrast, a history of steamrolling community should be rewarded, showing that the government is in control and prioritizes explicit promises to the feds and the voters over implicit promises to the local notables who form the base of NIMBYism. Spend money in growth regions In cities without much housing demand, like Detroit and Cleveland, the problem of housing affordability is one of poverty; infrastructure spending wouldn’t fix anything. This means that the housing grant should prioritize places with growth demand, where current prices greatly exceed construction costs. These include constrained expensive cities like New York and San Francisco, but increasingly also other wealthy cities like Denver and Nashville, whose economic booms translate to population increase as well as income growth, but unfortunately housing growth lags demand. Even poorer interior cities are seeing rent increases as people flee the high prices of richer places, and encouraging housing growth in their centers is welcome (but not in their suburbs, where housing is abundant and not as desirable). Look at residential, not commercial development In the United States, YIMBY groups have focused exclusively on residential development. This is partly for political reasons: it’s easier to portray housing as more moral, benefiting residents who need affordable housing even if the building in question is market-rate, than to portray an office building as needing political support. In some cases it’s due to perceived economic reasons – the two cities driving the American YIMBY discourse, New York and San Francisco, have unusually low levels of job sprawl for the United States, and in both cities YIMBY groups are based near city center, where jobs look especially plentiful. At the local and state level, this indifference to commercial YIMBY is bad, because it’s necessary to build taller in city center and commercialize near-center neighborhoods like the West Village to fight off job sprawl. However, at the federal level, a focus on residential development is good. This is a consequence of the inherent mistrust assumed in the incentive system. While economically, American cities need city centers to grow beyond the few downtown blocks they currently occupy, politically it’s too easy for local actors to bundle a city center expansion with an outrageously expensive urban renewal infrastructure plan. In New York, this is Penn Station redevelopment, including some office towers in the area that are pretty useful and yet have no reason to be attached to the ill-advised Penn Station South project digging up an entire block to build new tracks. Residential development is done at smaller scale and is harder to bundle with such unnecessary signature projects; the sort of projects that are bundled with it are extensions of urban rail to new neighborhoods to be redeveloped, and those are easier to judge on the usual transport metrics. # Trains are not Planes Trains and planes are both scheduled modes of intercity travel running large vehicles. Virgin runs both kinds of services, and this leads some systems to treat trains as if they are planes. France and Spain are at the forefront of trying to imitate low-cost airlines, with separately branded trains for different classes of passengers and yield management systems for pricing; France is even sending the low-cost OuiGo brand to peripheral train stations rather than the traditional Parisian terminals. This has not worked well, and unfortunately the growing belief throughout Europe is that airline-style competition on tracks is an example of private-sector innovation to be nourished. I’d like to explain why this has failed, in the context of trains not being planes. How do trains and planes differ? All of the following features of trains and planes are relevant to service planning: Taken together, these features lead to differences in planning and pricing. Plane and train seats are perishable – once the vehicle leaves, an unsold seat is dead revenue and cannot be packaged for later. But trains have low enough variable costs that they do not need 100% seat occupancy to turn a profit – the increase in cost from running bigger trains is small enough that it is justified on other grounds. Conversely, trains can be precisely scheduled so as to provide timed connections, whereas planes cannot. This means the loci of innovation are different for these two technologies, and not always compatible. What are the main innovations of LCCs? European low-cost carriers reduce cost per seat-km to around 0.05€ (source: the Spinetta report). They do so using a variety of strategies: • Using peripheral, low-amenity airports located farther from the city, for lower landing fees (and often local subsidies). • Eliminating such on-board services as free meals. • Using crew for multiple purposes, as both boarding agents and air crew. • Flying for longer hours, including early in the morning and later at night, to increase equipment utilization, charging lower fares at undesirable times. • Running a single class of airplane (either all 737 or all 320) to simplify maintenance. They additionally extract revenue from passengers through hidden fees only revealed at the last moment of purchase, aggressive marketing of on-board sales for ancillary revenue, and an opaque yield management system. But these are not cost cutting, just deceptive marketing – and the yield management system is in turn a legacy carrier response to the threat of competition from LCCs, which offer simpler one-way fares. How are LCC innovations relevant to trains? On many of the LCC vs. legacy carrier distinctions, daytime intercity trains have always been like LCCs. Trains sell meals at on-board cafes rather than providing complimentary food and drinks; high-speed rail carriers aim at fleet uniformity as much as practical, using scale to reduce unit maintenance costs; trains have high utilization rates using their low variable operating costs. On others, it’s not even possible to implement the LCC feature on a railroad. SNCF is trying to make peripheral stations work on some OuiGo services, sending trains from Lyon and Marseille to Marne-la-Vallée and reserving Gare de Lyon for the premium-branded InOui trains. It doesn’t work: the introduction of OuiGo led to a fall in revenue but no increase in ridership, which on the eve of corona was barely higher than on the eve of the financial crisis despite the opening of three new lines. The extra access and egress times at Marne-la-Vallée and the inconvenience imposed by the extra transfer with long lines at the ticketing machines for passengers arriving in Paris are high enough compared with the base trip time so as to frustrate ridership. This is not the same as with air travel, whose origins are often fairly diffuse because people closer to city center can more easily take trains. What innovations does intercity rail use? Good intercity train operating paradigms, which exist in East Asia and Northern Europe but not France or Southern Europe, are based on treating trains as trains and not as planes (East Asia treats them more like subways, Northern Europe more like regional trains). This leads to the following innovations: • Integration of timetable and infrastructure planning, taking advantage of the fact that the infrastructure is built by the state and the operations are either by the state or by a company that is so tightly linked it might as well be the state (such as the Shinkansen operators). Northern European planning is based on repeating hourly or two-hourly clockface timetables. • Timed connections and overtakes, taking advantage of precise timetabling. • Very fast turnaround times, measured in minutes; Germany turns trains at terminal stations in 3-4 minutes when they go onward, such as from north of Frankfurt or Leipzig to south of them with a reversal of the train direction, and Japan turns trains at the end of the line in 12 minutes when it needs to. • Short dwell times at intermediate stops – Shinkansen trains have 1-minute dwell times when they’re not sitting still at a local station waiting to be overtaken by an express train. • A knot system in which trips are sped up so as to fit into neat slots with multiway timed connections at major stations – in Switzerland, trains arrive at Zurich, Basel, and Bern just before the hour every half hour and depart just after. • Fare systems that reinforce spontaneous trips, with relatively simple fares such that passengers don’t need to plan trips weeks in advance. East Asia does no yield management whatsoever; Germany does it but only mildly. All of these innovations require public planning and integration of timetable, equipment, and infrastructure. These are also the exact opposite of the creeping privatization of railways in Europe, born of a failed British ideological experiment and a French railway that was overtaken by airline executives bringing their own biases into the system. On a plane, my door-to-door time is so long that trips are never spontaneous, so there’s no need for a memorable takt or interchangeable itineraries; on a train, it’s the exact opposite. # How Comparisons are Judged I’m about to complete the report for the Transit Costs Project about Sweden. For the most part, Sweden is a good comparison case: its construction costs for public transport are fairly low, as are those of the rest of Scandinavia, and the projects being built are sound. And yet, the Nordic countries and higher-cost countries in the rest of Northern Europe, that is Germany and the Netherlands, share a common prejudice against Southern Europe, which in the last decade or so has been the world leader in cost-effective infrastructure. (Turkey is very cheap as well but in many ways resembles Southern Europe, complete with having imported Italian expertise early on.) This is not usually an overt prejudice. Only one person who I’ve talked to openly discounted the idea that Italy could be good at this, and they are not Nordic. But I’ve been reading a lot of material out of Nordic countries discussing future strategy, and it engages in extensive international comparisons but only within Northern Europe, including high-cost Britain, ignoring Southern Europe. The idea that Italians can be associated with good engineering is too alien to Northern Europeans. The best way to illustrate it is with a toy model, about the concept of livable cities. Livable cities Consider the following list of the world’s most livable cities: 1. Vienna 2. Stockholm 3. Auckland 4. Zurich 5. Amsterdam 6. Melbourne 7. Geneva 8. Copenhagen 9. Munich 10. Vancouver The list, to be clear, is completely made up. These are roughly the cities I would expect to see on such a list from half-remembering Monocle’s actual lists and some of the discourse that they generate: they should be Northern European cities or cities of the peripheral (non-US/UK) Anglosphere, and not too big (Berlin might raise eyebrows). These are the cities that urbanist discourse associates with livability. The thing is, prejudices like “Northern Europe is just more livable” can tolerate a moderate level of heresy. If I made the above list, but put Taipei at a high place shifting all others down and bumping Vancouver, explaining this on grounds like Taipei’s housing affordability, strong mass transit system, and low corona rates (Taiwan spent most of the last two years as a corona fortress, though it’s cracked this month), it could be believed. In effect, Taipei’s status as a hidden gem could be legitimized by its inclusion on a list alongside expected candidates like Vienna and Stockholm. But if instead the list opened with Taipei, Kaohsiung, Taichung, and Tainan, it would raise eyebrows. This isn’t even because of any real criteria, though they exist (Taiwan’s secondary cities are motorcycle- and auto-oriented, with weak metro systems). It just makes the list too Taiwanese, which is not what one expects from such a list. Ditto if the secondary Taiwanese cities were bumped for other rich Asian cities like Singapore or Seoul; Singapore is firmly in the one-heresy status – it can make such a list if every other city on the list is as expected – but people have certain prejudices of how it operates and certain words they associate with it, some right and some laughably wrong, and “livable” is not among them. The implication for infrastructure A single number is more objective than a multi-factor concept like livability. In the case of infrastructure, this is cost per kilometer for subways, and it’s possible to establish that the lowest-cost places for this are Southern Europe (including Turkey), South Korea, and Switzerland. The Nordic countries used to be as cheap but with last decade’s cost overruns are somewhat more expensive to dig in, though still cheaper than anywhere else in the world; Latin America runs the gamut, but some parts of it, like Chile, are Sweden-cheap. Per the one-heresy rule, the low costs of Spain are decently acknowledged. Bent Flyvbjerg even summarized the planning style of Madrid as an exemplar of low costs recently – and he normally studies cost overruns and planning failures, not recipes for success. But it goes deeper than just this, in a number of ways. 1. While Madrid most likely has the world’s lowest urban subway costs, the rest of Southern Europe achieves comparable results and so does South Korea. So it’s important to look at shared features of those places and learn, rather than just treat Spain as an odd case out while sticking with Northern European paradigms. 2. Like Italy, Spain has not undergone the creeping privatization of state planning so typical in the UK and, through British soft power, other parts of Northern Europe. Design is done by in-house engineers; there’s extensive public-sector innovation, rather than an attempt to activate private-sector innovation in construction. 3. Southern European planning isn’t just cheap, but also good. Metro Milano says that M5 carries 176,000 passengers per day, for a cost of 1.35b€ across both phases; in today’s money it’s around$13,000 per rider, which is fairly low and within the Nordic range. Italian driverless metros push the envelope on throughput measured in peak trains per hour, and should be considered at the frontier of the technology alongside Paris. Milan, Barcelona, and Madrid have all been fairly good at installing barrier-free access to stations, roughly on a par with Berlin; Madrid is planning to go 100% accessible by 2028.
4. As a corollary of point #3, there are substantial similarities between Southern and Northern Europe. In particular, both were ravaged by austerity after the financial crisis; Northern Europe quickly recovered economically, but in both, infrastructure investment is lagging. In general, if you keep finding $10,000/rider and$15,000/rider subways to build, you should be spending more money on more subway lines. Turkey is the odd one out in that it builds aggressively, but on other infrastructure matters it should be viewed as part of the European umbrella.
5. Italian corruption levels in infrastructure are very low, and from a greater distance this also appears true of Spain. Italy’s governance problems are elsewhere – the institutional problems with tax avoidance drag down the private sector, which has too many family-scale businesses that can’t grow and too few large corporations, and not the public sector.

I’m not going to make a list of the cities with the best urban rail networks in the world, even in jest; people might take this list as authoritative in ways they wouldn’t take a list I made up about livability. But in the same way that there are prejudices that militate in favor of associating livability with Northern Europe and the peripheral Anglosphere, there are prejudices that militate in favor of associating good public transport with Northern and Central Europe and the megacities of rich Asia. All of those places indeed have excellent public transportation, but this is equally true of the largest Southern European cities; Istanbul is lagging but it’s implementing two large metro networks, one for Europe and one for Asia, and already has Marmaray connecting them under the Bosporus.

And what’s more, just as Southern Europe has things to learn from Northern Europe, Northern Europe has things to learn from the South. But it doesn’t come naturally to Germans or Nordics. It’s expected that every list of the best places in Europe on every metric should show a north-south gradient, with France anywhere in between. If something shows the opposite, it must in this schema be unimportant, or even fraudulent. Northerners know that Southerners are lazy and corrupt – when they vacation in Alicante they don’t see anyone work outside the hospitality industry, so they come away with the conclusion that there is no high-skill professional work in the entire country.

But at a time when Germany is building necessary green infrastructure at glacial rates and France and Scandinavia have seen real costs go up maybe 50% in 20 years, it’s necessary to look beyond the prejudice. Madrid, Barcelona, Rome, Milan, Istanbul, Lisbon, and most likely also Athens have to be treated as part of the European core when it comes to urban rail infrastructure, with as much to teach Stockholm as the reverse and more to teach Berlin than the reverse.

# Consolidating Stops with Irregular Spacing

There was an interesting discussion on Twitter a few hours ago about stop consolidation on the subway in New York. Hayden Clarkin, the founder of TransitCon, brings up the example of 21st Street on the G in Long Island City. The stop is lightly-used and very close to Court Square, which ordinarily makes it a good candidate for removal, a practice that has been done a handful of times in the city’s past. However, the spacing is irregular and in context this makes the stop’s removal a lower-value proposition; in all likelihood there should not be any change and trains should keep calling at the station as they do today.

What is 21st Street?

The G train, connecting Downtown Brooklyn with Long Island City directly, makes two stops in Queens today: Court Square, at the southern end of the Long Island City business district, and 21st Street, which lies farther south. Here is a map of the area:

At closest approach, the platforms of 21st are 300 meters away from those of Court Square on the G; taking train length into account, this is around 400 meters (the G runs short trains occupying only half the platform). Moreover, Court Square is a more in-demand area than 21st Street: Long Island City by now near-ties Downtown Brooklyn as the largest job center in the region outside Manhattan, and employment clusters around Queens Plaza, which used to be one stop farther north on the G before the G was curtailed to Court Square in order to make more room for Manhattan-bound trains at Queens Plaza. Court Square is still close to jobs, but 21st Street is 400 meters farther away from them, with little on its side of the neighborhood.

Stop spacing optimization

Subways cannot continuously optimize their stop spacing the way buses can. Building a new bus stop costs a few thousand dollars, or a few ten thousand if you’re profligate. Building a new subway stop costs tens of millions, or a few hundred million if you’re profligate. This means that the question of subway stop optimization can only truly be dealt with during the original construction of a line. Subsequently, it may be prudent to build a new stop but only at great expense and usually only in special circumstances (for example, in the 1950s New York built an infill express station on the 4 and 5 trains at 59th, previously a local-only station, to transfer with the N, R, and W). But deleting a stop is free; New York has done it a few times, such as at 18th Street on the 6 trains or 91st on the 1. Is it advisable in the case of 21st?

The answer has to start with the formula for stop spacing. Here is my earliest post about it, in the context of bus stops. The formula is,

$\mbox{Optimum spacing} = \sqrt{4\cdot\frac{\mbox{walk speed}}{\mbox{walk penalty}}\cdot\mbox{stop penalty}\cdot\mbox{average trip distance}}$

The factor of 4 in the formula depends on circumstances. If travel is purely isotropic along the line, then the optimum is at its minimum and the factor is 2. The less isotropic travel is, the higher the factor; the number 4 is when origins are purely isotropic, which reflects residential density in this part of New York, but destinations are purely anisotropic and can all be guaranteed to be at distinguished nodes, like business centers and transfer points. Because 21st Street is a residential area and Court Square is a commercial area and a transfer point, the factor of 4 is justified here.

Walk speed is around 1.33 m/s, the walk penalty is typically 2, the stop penalty on the subway is around 45 seconds, and the average unlinked trip on the subway is 6.21 km; the formula spits out an optimum of 863 m, which means that a stop that’s 400 meters from nearby stops should definitely be removed.

But there’s a snag.

The effect of irregular stop spacing

When the optimal interstation is 863 meters, the rationale for removing a stop that’s located 400 meters from adjacent stations is that the negative impact of removal is limited. Passengers at the stop to be removed have to walk 400 meters extra, and passengers halfway between the stop and either of the adjacent stops have no more walking to do because they can just walk to the other stop; the average extra walk is then 200 meters. The formula is based on minimizing overall travel time (with a walk penalty) assuming that removing a stop located x meters from adjacent stops incurs an extra walk of x/2 meters on average near the station. Moreover, only half of the population lives near deleted stops, so the average of x/2 meters is only across half the line.

However, this works only when stop spacing is regular. If the stop to be removed is 400 meters from an adjacent stop, but much farther from the adjacent stop on the other side, then the formula stops applying. In the case of 21st Street, the next stop to the south, Greenpoint Avenue, is 1.8 km away in Brooklyn, across an unwalkable bridge. Removing this stop does not increase the average walk by 200 meters but by almost 400, because anywhere from 21st south in Long Island City the extra walk is 400. Moreover, because this is the entire southern rim of Long Island City, this is more than just half the line in this area.

In the irregular case, we need to halve the factor in the formula, in this case from 4 to 2 (or from 2 to 1 if travel is isotropic). Then the optimum falls to 610; this already takes into account that 21st Street is a weaker-demand area than Court Square, or else the factor in the formula would drop by another factor of 2. At 610 meters, the impact of removing a stop 400 meters from an adjacent stop is not clearly positive. In the long run, it is likely counterproductive, since Long Island City is a growth area and demand is likely to grow in the future.

Does this generalize?

Yes!

In New York, this situation occurs at borough boundaries, and also at the state boundary if more service runs between the city and New Jersey. For example, in retrospect, it would have been better for the east-west subway lines in Manhattan to make a stop at 1st or 2nd Avenue, only 300-500 meters from the typical easternmost stop of Lexington. The L train does this, and if anything does not go far enough – there’s demand for opening a new entrance to the 1st Avenue stop (which is one of the busiest on the line) at Avenue A, and some demand for a likely-infeasible infill stop at Avenue C. These are all high-density areas, but they’re residential – most people from Queens are not going to 2nd Avenue but to Lex and points west, and yet, 2nd would shorten the walk for a large group of residential riders by around 400 meters, justifying its retrospective inclusion.

# Quick Note: Learning from the Past and the Present

There are two tendencies among Americans in the rail industry that, taken together, don’t really mesh. The first is to ignore knowledge produced outside North America, especially if it’s also outside the Anglosphere, on the grounds that the situations are too different and cannot be compared. The second is to dwell on the past and talk about how things could have been different and, therefore, to spend a lot of time looking at old proposals as a guideline.

The problem with this is that the past is a foreign country. They do things differently there. The world of the imagined past of modern-day Western romantics, usually placed in the 1950s or early 60s, is barely recognizable, economically or politically; Mad Men hits watchers on the head in its early seasons with how alien it is. The United States was an apartheid state until around 1964; France only decolonized Algeria in 1962; Germany had a deep state until the Spiegel affair of 1962 started to dismantle it and wouldn’t truly apologize for its WW2 crimes until the Kniefall and the fallout therefrom.

So as a public service, let’s look at some economic indicators comparing the US to the three low-construction cost countries that the Transit Costs Project is doing case studies about:

The US is comparable to Sweden on net – the higher GDP per capita is mostly an artifact of shorter vacation times. It is a considerably more developed country than Italy, by most accounts (except health care, where the US is more or less the worst in the developed world). Italy is a more developed country than Turkey. And Turkey, today, is considerably more developed than the US was in the imagined postwar golden age, even if it’s urbanizing later. The one indicator where they look similar, female LFP, masks the fact that the gender gap for employed women today isn’t especially high in Turkey and that, after a fall in female LFP in the late 20th century, today working outside the home is more middle-class, whereas in early postwar America it was considered a marker of poverty for a married woman to work.

So in that supposed golden age of an America before the Interstates, or when the Interstates were still in their infancy, GDP per capita was about comparable to Mexico today (and underinvestment in public transportation was comparable too; the Mexico City Metro’s expansion ground to a halt after AMLO was elected mayor). Women were only starting to emerge from the More Work for Mother era. Black people were subjected to literal apartheid. 65 was an old age to retire at (the majority of the increase in life expectancy at birth has occurred since age age 65 – it wasn’t mostly about declining child mortality).

Deindustrialization was nowhere on the horizon in 1960, which is a cause for celebration by people today who view industry as more moral than services. But the industrial jobs that are romanticized today were held by the era’s traditionalists to be morally inferior to the rapidly depleting farm jobs, and did not pay well until generations of wage increases brought about by unions. And Sweden, Italy, and Turkey are all deindustrializing rapidly; China today has a slightly lower manufacturing job share than the US had at its postwar peak, and elsewhere in the world than East Asia, there’s a serious issue of premature deindustrialization.

What about the law? Well, in 1960 the US had the same constitution as today, in theory, but the interpretative theories were completely different. The vast majority of the American constitution is unwritten (the word “filibuster” does not appear there) and there are vast differences in practice today and in the 1950s, when, again, members of the largest minority group risked being lynched if they tried voting in the states the majority of them lived. The party system at the time was extraordinarily loose; Julia Azari speaks of strong partisanship and weak parties today, but by postwar standards, both American parties are characterized by ideological uniformity and congressional command-and-control systems, even if the distribution of power within the parties is dramatically different from the European norm. Turkey might be comparable to postwar America – it’s hard to exactly say, since the two entities’ democratic systems are flawed in completely different ways. Italy and Sweden are not.

So the only thing that’s left is the romanticism. It’s the belief of 21st-century Americans that they could have ridden trains out of the old Penn Station, and worked in any of the prestige industries at the time, and done things differently. The constitution of the US today, its politics, its society, and its economy have little to do with their counterparts of 60+ years ago, but it’s useful for a lot of people to pretend that there’s continuity. It feels more stable this way. It just happens to be dangerously incorrect. Burn the past and look at the present.

# The Solution to Failed Process isn’t More Process

The US Department of Transportation has an equity action plan, and it’s not good. It suffers from the same fundamental problem of American governance, especially at the federal level: everything is about process, nothing is about visible outcomes for the people who use public services. If anything, visible change is constantly deprecated, and direct interference in that direction is Not What We Do. Everything is a nudge, everything has to be invisible. When the state does act, it must do so in the direction of ever more layers of red tape, which at this point are for their own sake.

Case in point: a 12-page PDF with many graphics and charts manages to fit in two giant red flags, both with serious implications for how USDOT views its mission. They showcase a state that exists to obstruct and delay and shrugs off social and developmental goals alike. The action plan should be dismissed and replaced with an approach that aims to dissolve anti-developmental institutions and favor action over talk.

Contractors, or users?

Most of the document does not concern itself with how to be more equitable for the users of public transportation in the United States. It doesn’t talk about racial differences in commuting patterns – it says poor people spend more of their income on transportation (as is the case for other basic staples) but ignores the issue where 61% of American public transport commuters are racial or ethnic minorities in a country that’s 62% white.

What it does talk about is the needs of contractors. The US has special programs for disadvantaged business enterprises (DBEs). In contracting, this is called MWBE in New York – minority- and women-owned business enterprise. New York requires 20% of contract value to go to MWBE, and since construction is an oligopoly owned entirely by white men and there is no interest in breaking said oligopoly, everything goes through a web of subcontractors to satisfice the law while driving up costs for the end users; one source at the MTA quotes a 20% premium to me just from the subcontracting web caused by this and other special restrictions.

In anti-left American media, the black slumlord who complaints that it is racist to levy fines on him for violating building codes is somehow a sympathetic figure, in preference to the people with the misfortune of living in one of his 100 apartments. Similarly, when Americans speak about income mobility in their country, they center the origin stories of billionaires, most of whom grew up comfortably upper middle-class, rather than whether a working poor person has much hope to ascend to the middle class.

It’s the same with the focus on MWBE. MWBE are not socially relevant. There is no social or developmental purpose in creating a class of business owners shielded from competition – in this case, federal contractors – and then trying to diversify it. Most people are not business owners; most people work for someone else and to get to work they need to commute, and for women and minorities, this is disproportionately likely to be public transport. The path forward is a federal repeal of all MWBE laws and their replacement with preemption forbidding states to enact similar laws. Federal power should dissolve failed local arrangements, free from the need to kowtow to local power brokers who have limited power beyond the local level and none at the federal level.

Process for the sake of process

Community meetings in the United States are a failure. The action plan recognizes this problem, and even begins to understand why:

* Public meetings are a common public involvement strategy, but can be inconvenient or impossible to attend for some. Physical meeting locations may be inaccessible for some, including those with disabilities. Virtual public meetings are inaccessible for people without internet access or computer literacy.

* Various methods may be needed to allow people with diverse circumstances to have a voice in decisions that affect their community. Adaptive engagement strategies can be a resource-intensive but valuable endeavor that is responsive to specific community needs, including different language and cultural backgrounds.

Unfortunately, the solution wants to accrete more process for its own sake. There is no positive use for a community meeting; the defenders of the process in multiple American cities, when I challenged them on this point, could not name to me a single useful thing that came out of them. But the negatives are numerous, and not fixable through multilingual meetings:

• The times at which meetings are held tend to privilege people who can take time off during work hours – the same class of already overprivileged business owners, comfortable housewives, and retirees, to the exclusion of people who work for someone else.
• Community as a concept is exclusive; in Cultural Theory terms, egalitarian systems tend toward strong boundedness and this is inherently exclusive in ways that market- and state-based systems lack. Outsiders who attempt to attend community meetings report being verbally harassed for not looking like the typical attendee, for example if they are much younger.
• Community meeting dynamics favor loudness and adversarial agitation. Social media has the same problem, with a growing body of published work about the effect of online harassment on people, disproportionately people from disadvantaged background. Yelling is believed to get results, and the idea that the state should punish it to let other voices than that of the biggest blowhard be heard is treated as so ridiculous that in popular culture it’s put in the mouth of a junta member.
• Local community is not relevant to how most people live in metropolitan areas. In New York, only 8% of workers work in the same community board that they live in (and even same-borough commutes are only 39%); the other 92% and their dependents socialize in citywide networks rather than locally. And yet, community boards, representing those 8% with local ties, are taken as closest to the people.
• People with limited English proficiency need not just government services in the relevant language but also relevant information. For example, Chinese immigrants receive information out of Chinese networks, which are not especially local to one specific Chinatown, but are often pan-Chinese or pan-Chinese-American. With much thinner sourcing than is available in English, they can form opinions about the issues most in the news, which tend to be national, but not about local issues. This is something every intra-European immigrant gets very quickly – it’s easier to find someone who speaks the same language with opinions about Annalena Baerbock than someone who speaks the same language with opinions about Bettina Jarasch, let alone any borough-scale politician (I do not remember a single conversation within queer Berlin spaces about borough-scale politicians).
• Local knowledge, to the extent it even exists, is not important, but the community meeting foregrounds it. Long-timers insist on talking about the history of every parklet and mural and shop and not about jobs or rents or public services; the community meetings elevates their concerns above memorizing sports statistics or similar trivialities.

The community meeting as a source of knowledge for the state to use or as a source of informal or formal power is a social stain wherever it is tried, and the impacts disproportionately fall on women, the young, minorities, queers, and immigrants. And yet an equity action plan that understands at least some of the problems created by the process cannot bring itself to recommend its abolition in favor of top-down state action, informed by the academic research of ethnographers to create universal design standards. No: it is recommending even more process. Process cannot fail; it can only be failed. Fair outcomes are out; endless red tape with all talk and no action is in.

# Quick Note: Regional Rail and the Massachusetts State Legislature

The Massachusetts state legislature is shrugging off commuter rail improvements, and in particular ignoring calls to spend some starter money on the Regional Rail plan. The state’s climate bill ignores public transportation, and an amendment proposing to include commuter rail electrification in the plan has been proposed but not yet included in the plan. Much of the dithering appears to be the fault of one politician: Will Brownsberger, who represents Watertown, Belmont, Back Bay, and parts of Brighton.

What is Regional Rail?

Regional Rail is a proposal by TransitMatters to modernize the MBTA commuter rail network to align it with the standards that have emerged in the last 50-60 years. The centerpiece of the plan is electrification of the entire network, starting from the already-wired Providence Line and the short, urban Fairmount Line and inner Eastern Line (Newburyport/Rockport Lines on timetables).

Based on comparable projects in peer countries, full electrification should cost $0.8-1.5 billion, and station upgrades to permit step-free access should cost on the order of$2 billion; rolling stock costs extra upfront but has half the lifecycle costs of diesels. An investment program on the order of high hundreds of millions or very low billions should be sufficient to wire the early-action lines as well as some more, such as the Worcester Line; one in the mid-single digit billions should be enough to wire everything, upgrade all stations, and procure modern trains.

Benefits include much faster trips (see trip planner here), lower operating and maintenance costs, higher reliability, and lower air and noise pollution and greenhouse gas emissions. For a city the size of Boston, benefits exceed costs by such a margin that in the developed world outside North America, it would have been fully wired generations ago, and today’s frontier of commuter rail electrification is sub-million metro areas like Trondheim, Aarhus, and Cardiff.

Who is Will Brownsberger?

Brownsberger is a Massachusetts state senator, currently serving as the Senate’s president pro tempore. His district is a mix of middle-class urban and middle-class inner-suburban; the great majority of his district would benefit from commuter rail modernization.

He has strong opinions on commuter rail, which are what someone unaware of any progress in the industry since roughly 1960 might think are the future. For example, here’s a blog post he wrote in 2019, saying that diesel engines are more reliable than electric trains because what if there’s a power outage (on American commuter rail systems that operate both kinds of vehicles, electric trains are about an order of magnitude more reliable), and ending up saying rail is an outdated 20th century concept and proposing small-scale autonomous vehicles running on the right-of-way instead. More recently, he’s told constituents that rail electrification with overhead wire is impossibly difficult and the only option is battery-electric trains.

Because he’s written about the subject, and because of his position in the State Senate and the party caucus, he’s treated as an authority on the subject. Hence, the legislature’s lack of interest in rail modernization. It’s likely that what he tells constituents is also what he tells other legislators, who follow his lead while focusing on their own personal interest, such as health policy, education policy, taxes, or any other item on the liberal policy menu.

Why is he like this?

I don’t know. It’s not some kind of nefarious interest against modernization, such as the trenchant opposition of New York suburbanites to any policy that would make commuter trains useful for city residents, who they look down on. Brownsberger’s district is fairly urban, and in particular Watertown and Belmont residents would benefit greatly from a system that runs frequently all day at 2020s speeds and not 1920s speeds. Brownsberger’s politics are pretty conventionally liberal and he is interested in sustainability.

More likely, it’s not-invented-here syndrome. American mainline passenger rail is stuck in the 1950s. Every innovation in the field since then has come from outside North America, and many have not been implemented in any country that speaks English as its primary language. Brownsberger lacks this knowledge; a lifetime in politics does not lend itself well to forming a deep web of transnational relationships that one can leverage for the required learning.

Without the benefit of around 60 years of accumulated knowledge of French, German, Swiss, Swedish, Dutch, Japanese, Korean, Austrian, Hungarian, Czech, Turkish, Italian, and Spanish commuter rail planning, any American plan would have to reinvent the wheel. Sometimes it happens to reinvent a wheel that is round and has spokes; more often, it invents a wheel with sharp corners or no place to even attach an axle.

When learning happens, it is so haphazard that it’s very easy to learn wrong or speculative things. Battery-electric trains are a good example of this. Europe is currently experimenting with battery-electric trains on low-traffic lines, where the fact that battery-electrics cost around double what conventional electric multiple units do is less important because traffic is that light. The technology is thus on the vendors’ mind and so when Americans ask, the vendors offer to sell what they’ve made. Boston is region of 8 million people running eight- and nine-car trains every 15 minutes at rush hour, where the places in Europe that experiment with battery tech run an hourly three-car train, but the without enough background in how urban commuter rail works in Europe, it’s easy for an American agency executive or politician to overlook this difference.

Is there a way forward?

Yes!

Here is a proposed amendment, numbered Amendment 13, by Senator Brendan Crighton. Crighton represents some of the suburbs to the northeast of Boston, including working-class Lynn and very posh Marblehead; with only four years in the State Senate and three in the Assembly, he’s not far up the food chain. But he proposed to require full electrification of the commuter rail network as part of the climate bill, on a loose schedule in which no new diesels may be procured after 2030, and lines would be electrified by 2028 (the above-named early action lines) to 2035 (the rest of the system). There are so far four cosponsors in addition to Crighton, and good transit activists in Massachusetts should push for more sponsorship so that Amendment 13 makes it into the climate package and passes.

# Providence Should Use In-Motion Charging for Buses

The future of bus transit is in-motion charging. This technology, increasingly common in Central Europe, is a hybrid of the trolleybus and the battery-electric bus (BEB), offering significant off-wire range with no need for centralized recharge facilities. Moreover, the range of batteries is improving over time and so is the recharge rate; in the limit, a pure BEB system may work, but in the present and near future it is not yet reliable in cold weather and requires diesel or oil heaters when the temperature is below freezing.

My original post on IMC technology speaks largely of New York and Boston, but Providence is an excellent place for implementing this technology as well, at least as good as Boston and far better than New York. As Rhode Island is thinking of how to invest in urban transit, it should take this technology into consideration, in addition to proposals for light rail along its busiest route (the Rapid, formerly the 99 and 11 buses) or a diesel BRT.

Transit Forward RI 2040

The guiding program, adopted in 2020, is called Transit Forward, and aims for a statewide plan including regional connections as well as the core of a solid mass transit network in Providence. The Rapid route is to be turned to light rail, perhaps, and multiple other core routes are to be upgraded to BRT standards (including the Rapid if light rail is rejected). This can be viewed here or here. Here is the metropolitan bus map:

Observe that multiple trunks are designed to have very high all-day frequency. Already today, service on Broadway and Westminster from Downcity to Olneyville interlines to a bus every 7.5 minutes; the proposal is to boost this to a bus every 7.5 minutes on Westminster and also one every 5 on Broadway. Past Olneyville, the buses branch at lower frequency. South Main is to have a core trunk route every 10 minutes and also a less frequent regional bus. The Angell/Waterman one-way pair is to have three routes running every 20 minutes, two every 30, and two less frequent express buses; closer in, this one-way pair shares the bus tunnel between Downcity and College Hill with routes running on Hope, labeled N117 in the plan.

On net, this is a massive expansion of bus frequency available to people in and around Providence. Were it available when I lived there, I would have an easier time traveling to Pawtucket, East Providence, and other such locations, often for gaming purposes; with the network as it is (or as it was in 2012), I would walk 6 km from my home in Fox Point to a gaming store in Pawtucket and it would still be faster than waiting 40 minutes for the bus in the evening.

IMC and branching

IMC as a technology permits buses to run about 10 km off-wire; the current frontier of the technology is that a minimum of 20-30% of the route needs to be wired. UITP presents it as an advantage in that the wiring cost is only 20-30% of that of a traditional trolleybus, but in fact the wiring cost is much lower, because the trunks can be wired while the branches are left unwired.

This advantage is hard to realize in a city like Chicago or Toronto, with a relentlessly gridded bus network and little branching. Both cities rely on rapid transit for downtown access, and have a bus grid layered on top of their radial metro systems to provide everywhere-to-everywhere connectivity and feed the trains. In such an environment, IMC saves 70-80% of the cost of a trolleybus, minus the additional cost of procuring a bus with a backup battery. This may sound like a lot, but trolleybus expansion is rare globally, so reducing the cost by a factor of 4 does not necessarily turn it into an attractive investment.

But in Providence, there is no grid. About 4 km of wire in each direction, from Downcity to past Henderson Bridge, are enough to electrify nearly the entire bus network connecting the city with East Providence. Another 3 km along South Main and I-195 complete electrification to the east. The N117 may need a short stub on Thayer in addition to the bus tunnel; Broadway and Westminster, totally around 6 km, should be enough to electrify buses to and beyond Olneyville; the core of Broad is planned to carry the N12 and R, both at high frequency, and is therefore a prime target for wiring as well; Charles should be enough to wire most of the buses going due north or northwest.

This way, a core trolleybus network with maybe 30 km of wire in each direction can electrify most of the bus network in Providence, without having to deal with the teething problems of BEBs.

The issue of legibility

One minor benefit of wire in Providence is that it helps casual riders make sense of the public transportation network. A big disadvantage of bus networks over rail is their poor legibility: the map has too many routes and a user is expected to know them all over an area, and there is no indication on the street as to where the buses go. Marked bus lanes help solve the latter problem, as does wire.

Trolleybuses are not streetcars. Their ride quality is that of a bus – usually better, occasionally worse, depending on who I ask. Their network structure is usually like the core of an urban bus network, and not like that of a modern light rail network, which a casual user can get at a glance. The presence of wire makes the system easier to see on the ground, helping improve legibility.

This is especially important in cities without grid networks – precisely the environments in which on purely technical issues IMC is already strongest. In Vancouver, the buses are largely gridded, and so it is generally clear where they go: they run on major streets like Broadway, King Edward, 41st, Arbutus, and MacDonald. But in Providence, it’s not always clear, especially in the seams between two networks. Broadway has a few choices of street connections toward Kennedy Plaza – do buses go on Sabin? Or Fountain? Or Empire to Washington? Westminster has no clear connection – do buses turn left or right on Franklin/Dave Gavitt Way? Wire helps make it clear for the confused passenger who doesn’t live in town, or who lives on the East Side and isn’t familiar with the Federal Hill street network.

This can be better than light rail

RIPTA is interested in making its highest-intensity route, now the R and in the future the N12, into a light rail line. I get where it’s coming from, but I have some worries. Providence development is frustratingly almost linear, but not quite; the train station is in a street loop off Main, and on the map above, the N12 veers off the straight path to connect to it. I don’t know what the optimal way is of serving such a destination, and it’s likely the answer will change over time based on changes in the technology and in other connections.

IMC can be good precisely for this. If the route is partly wired, then small deviations based on changes in the plan are viable, albeit at the cost of legibility. The same goes for uncertainty over which routes connect to which: the R today interlines the old 99 on North Main to Pawtucket and the old 11 on Broad to South Providence, but the plan is to instead connect South Providence to Downcity via the Jewelry District using the N8, and instead have the N12 primary route continue southwest to Warwick via Elmwood and Reservoir. Such changes require a commitment to mode: swaps are fine as long as both routes use the same mode – if they’re both light rail then it is viable and the same is true if they’re both buses, but not if one is rail and the other is bus. IMC downgrades both to a bus, but in a way that permits higher ride quality to some extent and lower emissions at very low costs.