The publisher of Human Transit, Island Press, is holding a big sale on their titles through September 30, so if you've been putting off buying the book, now is a great time to pick up a copy. The hardback is marked down to $35.00. the paperback just $17.50!
Island Press has my book Human Transit on sale now- get a phyiscal paperback copy for as little as $17.50, or splurge and pick up the hardback for $35.00! This is half the normal retail price on both, and if you haven't had a chance to buy the book yet, you are unlikely to find the print version any cheaper.
Follow the link to Island Press to buy now. No telling when the sale will end, so act fast!
This is not a balanced book review. While I will start with some general praise of this new book, I must focus on a few passages about public transit that are both misleading and potentially harmful. I do this not to challenge these authors in particular, but because these mistakes are so common in urbanist writing and need to be called out wherever they appear.
Reid Ewing and Keith Bartholomew, both at the University of Utah, have a new large-format paperback offering a concise overview of the basics on Pedestrian and Transit-Oriented design. If you want a good glossary of key urbanist concepts such as imageability and coherence, or you want a good and well-cited argument for local street connectivity, this is your book.
Very usefully, the book is organized as a series of checklists: Here are the features that you must have to be considered transit-oriented design, here are others that are desirable. It's designed to be handy to the time-crunched developer or policy person. In fact, it meets one of the most important standards for an influential book in our distracted age: You can get most of the message by just looking at the pictures and reading the section headings.
The writing is good, too, clear and with careful attention to explaining and demystefying concepts. With one exception, I could recommend this as a good reference guide to the key concepts of pedestrian-oriented design.
As a guide to transit-oriented design, however, it has a fatal flaw: The authors make recommendations about transit that make sense from a design and development point of view but are nonsense to many experienced transit planners. These recommendations will sound elitist and tone-deaf if you present them to your transit agency. As always, I emphasize sound; I've talked with enough urbanist writers to know how good their intentions are; they are mostly genuinely surprised when their comments about transit backfire. But it's not a hard mistake to avoid. I am going to take apart a critical passage in the book not because it's typical -- it's an unusual flaw in a good book -- but because it illustrates a lingering problem with urbanist discussions of transit in general, one that I hope we are close to moving beyond.
Ewing and Bartholomew lead off their transit discussion with this tired old chestnut:
In the quest for efficiency, transit has become dull and utilitarian, part of the problem reather than the solution to today's lifeless streetscapes (Coppe 1991). [p 82]
If this generalization is really about "today," then how is it bolstered by a 22-year old citation? Obviously it's true to a degree, more in some cities than others, but there has been transformative progress in the last two decades. Fleet, facilities, and technology have been upgraded across the developed world, often with the input of great designers. Do transit agencies get no credit for the evolution in the comfort, openness and access that have happened over the last generation?
More fundamentally, this line conveys disinterest of the nature of transit's success, a disinterest that is tragically common in urbanist professions. The word efficiency is used as though all readers would agree it's a misguided goal. But when working under any fixed budget as transit agencies do, efficiency is the same thing as abundance. (When something called efficiency is genuinely destructive or unsustainable, it should be called false efficiency. Freeways, fracking, and industrial farming may be less efficient than they look because of externalized negative impacts. Questioning those things doesn't amount to questioning efficiency.)
As for the word utilitarian, it has a technical meaning in philosophy but here it's a dismissive word meaning useful. Anything that scales to a vast network that's potentially useful to thousands or millions of people can be called utilitarian. Great transit agencies wear this term as a badge of honor. What's more they prove that usefulness is beautiful.
But the authors dig themselves deeper. After showing us pictures of charming, distinctive bus shelters in two wealthy communities that can afford them, they write:
In some cases, transit operators might do better by putting fewer buses on the street at times of low demand, and diverting the money they save into bus stop amenities and fleet facelifts.
This, urbanist friends, crosses a bright red line called upward redistribution of wealth.
This book appears at a time when many US transit agencies have been slashing transit service for the last five years, driving away legions of riders. Portland, for example, has had its inner city grid network gutted -- mostly cut to 20 minute frequencies at which the connections on which it relies are almost impossible -- even though frequent transit service is a foundational element in the City of Portland's neighborhood development policies.
Any "low-ridership" services that have survived all that carnage are serving popular and important non-ridership goals. They are not going to be cut to build nicer bus shelters. Doing so could also be illegal in the US if you're using Federal funds: US Title VI legislation (part of the 1964 Civil Rights Act) is designed to prevent exactly this kind of upward redistribution of the benefits resulting from public investment. All US transit agencies that receive Federal funds must do extensive analysis to prove they are treating low-income and minority riders fairly in both service and infrastructure.
So if you follow this book's advice, and tell your transit agency they should cut service and force lower income riders to buy cars so you can pay for nicer bus shelters, it doesn't matter how noble your intentions are. You will sound elitist. You will sound especially hostile to the burgeoning environmental justice agenda that is already embodied in civil rights legislation, and that has its own strong nexus with the ultimate outcomes that we call sustainability. If you prevail in guiding the policy of your transit agency, that agency could be exposed to civil rights lawsuits as a result. Do you really want this many enemies?
It doesn't help that in suggesting service cuts at "times [rather than places] of low demand," the authors are just repeating a common misconception. Ridership at different times of day is interdependent, if only for the obvious reason that most transit trips are round trips. If you cut service and thus reject a customer at one time of day, you'll likely lose their business in the other direction as well. The most obvious "time of low demand," the late evening, is also a "guaranteed ride home," which means it affects the overall attractiveness of the product. Finally, lower-income riders who form the bedrock on which transit grows are especially likely to be travelling in the evening; cut their service, force them to spend their scarce money on cars, and you've shoved them further into poverty.
A consistent pattern of all-day service (including "times of low demand") is a powerful tool for fostering lower vehicle ownership. That's is why many transit agencies are now committing to a policy "Frequent Network" that guarantees service over a certain span regardless of trip-by-trip ridership. (These policies, important in guiding true Transit-oriented Development at regionwide scale, deserved a mention. Policies in the Portland and Vancouver BC regions could both have been cited. Indeed, the book is silent on the urgent question of how to recognize a suitable site for TOD.)
I love distinctive transit shelters as much as anyone, but not if they are defined as an alternative to the sheer quantities of service that cities need and that ridership would reward. (Canadian midsized cities, for example, generally have about twice the ridership per capita of similar US cities, not becuase their shelters are cuter but becuase they run about twice as much service per capita.)
Distinctive, adorable shelters can still come about in one of three entirely reasonable ways. Either:
Developer-funding (also endorsed in the book) is often the purest nexus of all, but city funding is also a healthy trend. City governments are much better placed than regional transit agencies to make investments that express civic identity and character. Most US cities can also do improvement districts that focus the cost on the landowners who will most benefit. Still, it's usually wealthier communities that can afford to do this, so it's deeply misleading to present these specialized shelters as realistic examples for cities in general, let alone to suggest that cash-strapped agencies should reject existing riders in order to pay for them.
It's hard to even criticize Ewing and Bartholomew for these howlers. As long as I've been in the business, I've heard leading urbanists lecturing transit planners about how they should abandon their obsession with abundant service and focus on aesthetics instead. As someone with serious credentials in the arts, my response is always that I understand the aesthetic values that the urbanist is describing, but that their recommendation is pointless until they own the consequences of the cuts they are implicitly proposing to fund these things.
To be fair, transit agencies have been slow to engage urbanists in their own language, which requires staff with appropriate expertise. This, however, has improved dramatically over the last decade. Most leading transit agencies in major US cities have design and land use professionals on staff. Working urban designers and architects are responding constructively to transit agency input, and respectful conversations between the fields are happening more than ever. Most urban design and architecture professonals that I deal with are sensitive to real-world transit issues and open to learning about transit agency perspectives, so we can hope for a continued spread of insight on these issues.
Indeed, Ewing's and Bartholomew's book shows how far the urbanist discourse has come in respecting transit and the diversity of its riders. They speak mostly of "transit," avoiding rail vs. bus arguments, and their photos show buses as accepted parts of the urban landscape deserving of attention. This is real progress, still controversial in some quarters. It was partly in the context of this larger sensitivity that the passages quoted above were so shocking.
In the long run, urbanist thinkers who discuss transit must learn to respect transit network design and policy as a genuine expertise -- something that's worth learning about before you comment on it. Again, my own experience suggests that the practice is ahead of the literature in this regard. This book -- very useful on all subjects except transit policy -- shows how far urbanists' respect for transit agencies has come since the early days of the New Urbanism, and how much -- or perhaps how little -- remains to be done.
"Once in a while, a book comes along that summarizes most of what's important about a particular subject, and does so in a way that's lucid and effortless. One such book is Jarrett Walker's Human Transit."
I specifically like Bill's praise for the earliest CNU conferences, where everything happened in plenary and as a result, people had to listen to things they might not want to hear.
From the book's co-author:
I was glad that you urged "lazy students" via your Human Transit blog to read The Death and Life of Great American Cities, and I enjoyed reading your thoughtful commentary for the City Builder's Book Club on Jane Jacobs and transportation!
I thought I'd let you know about a book that might have escaped your notice called Genius of Common Sense: Jane Jacobs and the Story of "The Death and Life of Great American Cities." It's just come out in paperback with a new cover featuring a heretofore unpublished 1963 photo of Jane alongside her main mode of transportation – her bicycle – on the streets of New York.
Genius of Common Sense was originally intended for young adults but has caught the attention of the likes of Robert Caro, Jason Epstein, and Robert Campbell as a solid introduction to the life and work of Jane Jacobs for adults too. With more than 100 images, it follows her through the publication of Death and Life and her New York battles against urban renewal and expressways.
Sounds interesting! Anyone want to write a review as a guest post?
Taras Grescoe. Straphanger: Saving Our Cities and Ourselves from the Automobile. Macmillan, 2012.
When the publisher of Taras Grescoe’s Straphanger asked me to review the book, I felt the usual apprehension. Shelves are full of books that discuss transit from a journalist’s perspective. They often get crucial things wrong, as do many journalists’ articles on the topic. I wondered I was going to endure another four hours of watching readers being innocently misled on issues that matter.
Grescoe does a little of that, but he also shows why spectacular writing compensates for many problems of detail. Straphanger is a tour de force of compelling journalism and “travel writing” – friendly, entertaining, funny, pointed, and (almost always) compelling. Like any good explainer, he announces his prejudice at once:
I admit it: I ride the bus. What’s more, I frequently find myself on subways, streetcars, light rail, metros and high-speed trains. Though I have a driver’s license, I’ve never owned an automobile, and apart from the occasional car rental, I’ve reached my mid forties by relying on bicycles, my feet, and public transportation for my day-to-day travel … I am a straphanger, and I intend to remain one as long as my legs will carry me to the corner bus stop.
Grescoe and I have almost all of this in common, but I felt a pang of regret at this posture. To the mainstream, car-dependent people who most need this book’s message, Grescoe has just announced that he’s a space alien with three arms and a penchant for eating rocks. But there’s a positive side: once you decide you’re not in danger, eccentric tourguides can be fun. Perhaps I have a poor dataset from living in “officially weird” Portland, and before that in San Francisco, but in a culture that seems increasingly welcoming of eccentricity and difference, there may be an audience for Grescoe among the motoring set.
Because this is what Grescoe is at heart: A great tourguide, in this case a travel writer, showing you around some fascinating cities, exploring intriguing transit systems, and introducing us to vivid and engaging characters, all while having fun and sometimes dangerous adventures. These last are important; Grescoe has had enough traumatic and confronting experiences that he can describe straphanging as a form of endorphin-rich adventure analogous to mountain climbing or skydiving. I look forward to the movie.
Statistics are cited lightly but to great (and usually accurate) effect. Effective and quotable jabs are everywhere:
“The personal automobile has, dramatically and enduringly, broadened our horizons. In the process, however, it has completely paved them over.
Grescoe has a great eye for characters, too. Who can fail to be charmed, for example, by this portrait of a character I hadn’t known: Bogotà mayor Antanas Mockus, alter-ego of his successor, the aggressive and practical Enrique Peñalosa:
Working with a tiny budget and no support from district councillors, Mockus focused on … undermining cycles of violence through jester-like interventions in daily life. He dismissed the notoriously corrupt traffic police and hired four hundred mimes to shame drivers into stopping at crosswalks. ... Taxis drivers were encouraged to become “Gentlemen of the Crosswalks,” and every new traffic fatality was marked with a black star prominently painted on the pavement. To discourage road rage and honking, he distributed World Cup-style penalty cards to pedestrians and motorists, a red thumb’s down to signify disapproval, a green thumbs up to express thanks for a kind act … Seeing tangible evidence of municipal progress, citizens once again began to pay their property taxes … and the once-bankrupt city’s finances began to recover.
What’s wrong with this book? Well, if it’s travel writing, nothing; travel writing is about the adventure, and while you learn things from it, you expect to learn subjective, unquantifiable things that may be inseparable from the character of your guide. Journalism, on the other hand, has to get its facts right, or at least state its biases. Grescoe gets a pass on his largest biases, mostly because he’s entirely aware of them and happy to point them out.
But there are a few mistakes. Like many commentators, Grescoe throws around meaningless or misleading data about urban densities. Here’s a typical slip:
Thanks largely to the RER, the metropolitan area of Paris, with over 10.2 million residents, takes up no more space on the Earth’s surface than Jacksonville, Florida, a freeway-formed city with fewer than 800,000 residents.
This doesn’t seem to check out, unless some subtle and uncited definition of metro area is being used. (Wikipedia tells me that the City of Jacksonville is 882 sq mi in area while the Paris with 10.3 million residents is 1098 sq mi.) But even if it did, this is the classic “city limits problem.” Jacksonville is a consolidated city-county whose “city limits” encompass vast rural area outside the city, whereas “metro Paris” is by definition a contiguous area that is entirely urbanized. An accurate comparison with metro Paris would look only at the built-up area of Jacksonville, which is tiny compared to Paris. The point is that any talk about metro areas or cities is prone to so many different definitions, including some really unhelpful ones, that it’s wrong to cite any urban density without footnoting to clarify exactly what you mean, and how it’s measured. Grescoe is far from alone in sliding into these quicksands.
As with many journalists, Grescoe’s sense of what would be a good transit network is strongly governed by his emotional response to transit vehicles and technologies. Grescoe is very enamored with rapid transit or “metro” service to the point that he sometimes misses how technologies work together for an optimal and liberating network.
He claims, for example, that there should be circular metro lines around Los Angeles, Chicago, and Toronto. In fact, circular or “orbital” services (regardless of technology) rely not just on network effects but also on being radial services into major secondary centers. This is why the Chicago Circle Line made no sense: Chicago is so massively single-centered that there are few major secondary centres sufficient to anchor a metro line until you get way out into the suburbs, at which point concentrations of jobs are laid out in such transit-unfriendly ways that no one line could serve them anyway. Chicago is going the right direction by improving the speed and usefulness of its urban grid pattern of service – a mathematically ideal network form that fits well with the shape of the city. Toronto has similar geography and issues. As for Los Angeles, this is a place with so many “centers” that the concepts of radial vs orbital service are meaningless. Especially here, where travel is going so many directions and downtown’s role is so small, the strong grid, not the circle, is the key to great transit.
Grescoe is clear enough about his strongest bias:
“I don’t like buses. … Actually, I hate them.”
Despite his opening statement that “I ride the bus,” Grescoe repeatedly associates buses with losers, and with unpleasant experiences. In correspondence with me, he wrote: “The anti-bus bias you perceive was a concession to North American readers whose experience of buses tends to be negative.” Again, this is understandable as travel writing, but it’s tricky as journalism and very tricky if the purpose is advocacy. When you presume a bias on the part of your reader, with the intent of later countering it, you can’t really control whether you’ve dislodged the bias or reinforced it. I felt the bias being reinforced; other readers may have different responses.
Again, the problem with anti-bus bias is not that I don’t share it. The problem is that if you set transit technologies in competition with one another, the effect is to undermine the notion that technologies should work together as part of a complete network. If you want a network that will give you access to all the riches of your city, buses are almost certain to be part of it – even if, as in inner Paris, you have the densest subway system in the world. Hating buses – if that becomes your primary focus -- means hating complete networks.
When it comes to Bus Rapid Transit, Grescoe accepts the common North American assumption that the place to see BRT is Bogotà or Curitíba. So he comes back from Bogotà with the near-universal reaction of North American junketers there: The massive structuring BRT is really impressive in the numbers it carries, but hey, this is the developing world. Not only is car ownership low but it’s more authoritarian in its politics, giving mayors the power to effect massive transformation fast without much consultation. What’s more, these massive busways are effective but really unpleasant as urban design – not something I’d want in my city. Respecting the effectiveness and utility of the Bogotà busways, Grescoe does endorse Bus Rapid Transit in secondary corridors, but he has not seen busways done completely for a developed-world audience.
North Americans who want to experience successful Bus Rapid Transit in a developed-world context should skip South America and visit Brisbane, Australia, where a wealthy modern city moves, in part, on a complete network of beautifully designed, landscaped, and highly functional busways that flow into an underground segment right through the heart of downtown, and that are designed to provide an extremely frequent rapid-transit experience. There are some European pieces of good busway, such as Amsterdam’s Zuidtangent. But you have to go to Brisbane to see an uncompromised developed-world busway network, one that provides reliable operations end to end.
While Straphanger’s flirtation with anti-bus stereotypes was troubling to me, there’s a limit to how much Grescoe can be criticized for this. This is journalism of its time, and the bus=loser stereotype is still of our time in some cities. It’s up to each of us to decide whether to seek experiences that confirm our stereotypes or those that might contradict them, but nobody can challenge all of their stereotypes at once. Grescoe does eagerly challenge many other destructive attitudes throughout the book, and the brilliance of a book lies in the way it brings delight and confidence to the experience of both using and advocating transit and great urbanism. I heartily recommend this fun, enlightening, and inspiring read.
I will be appearing with Darrin Thursday Wednesday night in Seattle, to promote both of our books. Details in the far-right column under my photo.
For my review of Darrin's previous book, My Kind of Transit, see here. Note that Darrin is such a classy guy that he links to my review on his website, even though my review raised major objections to that book.
Darrin is a great writer, a keen observer, and a committed urbanist. While we have utterly different perspectives (compared by Treehugger's Lloyd Alter here and by Slate's Tom Vanderbilt here) we agree about almost everything that really matters. I look forward to reading and reviewing his new book, and meeting him again in Seattle on Wednesday.
In his 2010 book Transport for Suburbia, Paul Mees notices a fallacy that seems to be shared by sustainable transport advocates and car advocates. Both sides of this great debate agree that effective transit requires high density.
Sustainability advocates want higher urban densities for a range of reasons, but viability of public transit is certainly one of them. Meanwhile, advocates of car-dominance want to argue that existing low densities are a fact of life; since transit needs high density, they say, there’s just no point in investing in transit for those areas, so it’s best to go on planning for the dominance of cars.
Mees calls on his fellow transit advocates to let go of the idea that good transit requires high densities:
The central argument of this book is that density is not destiny. Transport policy itself has a bigger impact on transport patterns than urban planners have realized, and suburbs don’t have to be totally reliant on the car. Planners who insist that car dominance can only be addressed by impossibly large increases in density may actually be entrenching the problem they are trying to solve.
Transit does depend on density, but there are three problems with saying that “transit requires high density.”
Mees is right that “density is not destiny.” Cities of any density can make better or worse transit choices and achieve significantly different outcomes as a result. But density is still an overwhelming force in determining the possibilities and outcomes of transit, and we can’t begin to make good transit decisions until we understand it.
Density is hard to talk about for two reasons: It’s very emotional and it’s hard to define and measure.
The emotions are inevitable: Whenever we talk about urban form, people hear us making judgments about their homes. I can stand in front of a group of citizens and talk about how a certain kind of development pattern implies certain consequences for transit, and thus for sustainability, and thus for civilization. As we talk, it may appear that we’re having a thoughtful and educational discussion about good and bad design. But some people in the audience have chosen to make their homes in the very development pattern that I’m describing, and to those people, I’m saying that their home is good or bad.
Once you hear that, you’re likely to have a strong emotional reaction that makes you deaf to rational argument. On some level, consciously or unconsciously, you’re going to feel as though I’d walked into your own livingroom and told you that your decor is not just ugly but a threat to civilization. We all feel defensive about home.
But emotions often hide inside things that look like facts, and density "facts" are a great example. In transit arguments, people say things like “the net density of Toronto is ###/hectare,” because this sounds like a fact and therefore conveys some authority to their argument. In reality, though, there are several possible meanings of “density” in that sentence, as well as several possible definitions of “net” and ”Toronto.” Briefly:
So the statement “the net density of Toronto is ###/hectare” is really as subjective as the statement “I think that cities should have more open space, narrower streets, and should have single governments covering the entire urban area.” Because each of those opinions can affect how you choose to define “net,” “density,” and “Toronto,” which in turn determines the number that you declare, with cold factual authority, to be the net density of Toronto.
At the core of Mees’s book, for example, is a table that compares the gross residential density of a bunch of urban areas with the transit performance in each area. The point of the table is to show that there’s really no relationship between the two. Before we look at some fun facts from this table, remember that definitions are everything. So in this case:
So with those cautions, here’s a taste of Mees’s scandalous numbers:
|Metro Area||Density (pop/ha)||Transit
mode share for work trips.
The density figures are calculated to shock. Los Angeles is denser than New York? Yes, that’s what happens when you average over a huge contiguous metro area. Your own impression of “New York” is probably formed by the massed and soaring towers of Manhattan, but New York is a dense city surrounded by a lot of very low-density suburbs that are all included in this concept of “metro New York.” Likewise, your stereotype of Los Angeles may be a ranch-style house with a big pool on a cul-de-sac, which implies a very low density, but in fact much of greater Los Angeles is four-story apartment buildings lined up for mile after mile. Obviously, our impression of the density of a city is based on the part of it we choose to remember, or that we tend to see on television. The average density of the whole urban area may be entirely different.
To me, Mees’s table proves that average density over a whole urban area is the wrong kind of density for understanding transit. The impression you probably have of the densities of these cities is actually closer to the kind of density that matters.
Transit reacts mainly with the density right around its stations. It is in the nature of transit to serve an area very unevenly, providing a concentrated value around its stops and stations and less value elsewhere. So what matters for transit is the density right where the transit is, not the aggregate density of the whole urban area.
Of course, what matters even more precisely is how much stuff is within walking distance of a station, so it's not just density (the amount of stuff in a fixed radius) but the completeness of the pedestrian network. A poorly connected pedestrian network can ensure that much of the stuff that's within a 400m radius is not in a 400m walk.
Consider Las Vegas, which Mees finds to be denser than highrise Vancouver. The Las Vegas economy is based on hospitality and entertainment, labor-intensive industries with low average wages. So the city needs a lot of housing suited for lower incomes. The Las Vegas way is to build utterly car-dependent apartment buildings on a vast scale, achieving all of the disadvantages of density with none of its benefits. Consider:
For scale, the width of this entire image is about 0.55 miles, or 0.9 km. The arterials along the south and west edges of the image are the only streets straight and fast enough for efficient transit. Note how these large apartment developments are soundwalled from most direct access to these arterials, and how the accesses they have tend to come out at points where there's no controlled intersection, so the arterial is dangerous to cross. (Two-way transit trips always require stops on both sides of the street, so if you can't cross the street, you don't really have access.)
So yes, Las Vegas has massive quantities of apartment buildings, which yield a high average density. But at two levels of scale, these are deployed in patterns that make effective transit difficult. On a macro level, Las Vegas is mostly midrise apartments spread over a large area, requiring transit to cover more distance to serve them; this is the most obvious explanation for Las Vegas's low transit performance compared to highrise Vancouver. But the micro explanation is important too. In the details of street pattern and pedestrian circulation, typical Las Vegas urban fabric is designed for motorists and hostile to pedestrians. Average urban density says nothing about either of these factors, even though they are what really determine the transit experience in each city.
It's inevitable that in comparisons between cities, we're going to hear average density figures. These figures are better than nothing when it comes to making global comparisons. The famous databases created by Jeffrey Kenworthy and Peter Newman, for example, are useful in showing how a range of sustainability outcomes vary with density.
But averages are dangerous, especially in transit. Averaging sounds like a credible way to draw a simple fact out of a huge and diverse reality, but often, averages are just not the fact that matters. In a recent post on the perils of average success, I pointed out that no transit customer really cares about average frequency, or average lateness, or average crowding. By the same token, transit advocates need to be suspicious of average density. What matters is the density around the transit system. How can we best measure that?
 Fig 4.1 p 60
 In the US, “an ‘urbanized area’ is defined for each metropolitan region, made up by combining adjacent ‘census blocks’ (the smallest units for which data are collected) with more than 1000 residents per square mile, or 386 per square kilometre. … Canada defines “urban area” on an almost identical basis to the US, using a density threshold of 400 [residents] per square kilometre.” The data is from 2006 census in Canada, 2000 in the US.
Richard Gilbert and Anthony Perl. Transport Revolutions: Moving People and Freight without Oil [2nd edition]. Earthscan and New Society Publishers, 2010.
As you’ve probably heard by now, the world is starting to run out of readily-accessible oil, and most rational predictions are that oil prices will continue to rise to reflect the increasing difficulty and risk involved in pursuing new supplies. How will that change our transport system? What kinds of change are needed? What technologies most urgently need research? And who will lead these changes?
Transport Revolutions: Moving People and Freight without Oil, is one of the most through analyses of this problem available to the general reader. While plenty of frightening books on this topic are available, Transport Revolutions is an essential counterpoint: it takes the kind of gentle and optimistic tone that you’d use to coax a suicidal friend off the ledge, or for that matter to pry anyone off of long-held but doomed opinions.
But the book goes further. The message is still that we need a revolution, but not quite the one that many of us have in mind.
Car-based thinking is so dominant in the US that attention has focused mostly on ways to solve the problem that let us still have lots of cars and not much limit on where we can drive them. These solutions include biofuels, diesel-electric hybrids, various kinds of battery technology, and hydrogen. One by one, Perl and Gilbert knock down all of them, predicting that each will develop but remain marginal to the real scale of the problem.
It looks pretty clear that the long-term answer is some form of electric motor, both because electricity can come from sustainable sources and because electric motors are highly efficient and give off little or no noise or pollution. But Perl and Gilbert argue that the crux of the problem is not sustainable power generation, but rather the means of storing energy for portable use; in other words, batteries. And the hard fact is that there just isn’t a battery, or even a sound technical basis to hope for a battery, that approaches the efficiency of internal combustion.
The crux of the crux is that petroleum has a very high energy density, which can be thought of as the energy stored divided by the mass required to store it. Batteries, by comparison, are just too heavy compared to the amount of energy that they can deliver, so when you put them in a mobile vehicle, they lose a lot of their efficiency to the work of transporting their own weight, and don’t have much left over to transport us or our cargo.
All this is carefully explained, and leads Gilbert and Perl to a striking conclusion: We will need to shift most of our mechanical transport to “grid-connected vehicles” (GCVs), vehicles -- like trolleybuses and electric rail lines – that can draw power from the grid continuously (and increasingly, return surplus energy back to the grid as well). At first, this may sound like a revolution in the direction of passenger transit, and much of it is. Gilbert and Perl call for high-speed rail replacing intercity aviation, growth of urban public transit, and so on.
But their vision goes further, to a network of “grid connected” roads, and a crucial moment, this vision turns into something that looks to the authors like Personal Rapid Transit (PRT).
Here’s the transition:
One [possible pathway toward implementation of a GCV-based land transport system] is via the plug-in hybrid car … Extensive operation of such vehicles could lead drivers to want more use of their electric motors. To facilitate this, governments or entrepreneurs could provide means of powering htem along major routes, accessible by appropriately equipped vehicles while in motion. When such en-route powering is sufficiently extensive, [electric vehicles] with only batteries and retract able connectors could prevail over plug in hybrids. As the grid-connection expands, the needf or off-grid movement would decline. Roads could be supplemented and even replaced by lower-cost guideway infrastructure. At the same time, vehicles would evolve to move only on the guideways. They would be as light as possible and, where appropriate, be assembled into trains. They would comprise PRT.
Another pathway could involve the evolution of public transport toward supplementation of or even replacement by PRT. This could be driven by PRT’s low energy cost and, perhaps even more, by its potentially low infrastructure cost. … An analysis for Corby, UK, compared costs of PRT and lighter ail. For similar initial investment, operating costs, and fare structure, PRT would carry almost twice as many passengers annually …
The second of these paths is almost certainly an illusion. You can do all kinds of comparisons of existing transit technology with proposed PRT technology, but none of these changes the physical fact that PRT requires carrying people in more vehicles, which means hauling around more metal per passenger. If higher oil prices caused a huge shift in demand to some form of automated transit, PRT would have to move more metal per passenger than conventional transit would do, and that would almost certainly be the decisive factor in its ultimate energy-efficiency. (An argument against this point would need to show that PRT is so dramatically lighter in weight than lightweight conventional transit [e.g. Vancouver’s SkyTrain] that it ends up moving fewer tons of metal per passenger. And this comparison would have to be against lightweight rapid transit alternatives. If anyone has made that argument, please point me to it.)
But the first path is probably worth contemplating at least as a thought experiment. Suppose we keep our current levels of car use, but gradually convert to grid connected cars. I guess we’re to imagine giant catenary systems above every street and highway, and something like trolley poles or pantographs on top of each private vehicle. However much they might love the freedom of the open road, motorists with hybrid vehicles would be motivated to connect to these catenaries at every opportunity, because their off-wire power options would be so expensive.
At that point, all we need is an automated system to combine cars into “trains” and we have PRT. I suppose we could arrive at that route, but this is so unlike the station-based PRT being proposed today that I’m not sure the term is even useful in understanding it.
[One nasty technical detail: grid-connected vehicles on tires need to route both directions of the electric circuit through the overhead catenary. That’s why trolley buses have two wires, while overhead-powered rail has only one. With two wires, you have to connect to them with poles, because the two sides of the circuit have to be kept apart. Trains, by contrast, are grounded through the rails and therefore need only one wire above. That means trains can meet this wire with a large horizontal structure -- called a pantograph -– which easily accommodates lateral motion. It’s a fine joke, really, by the technology gods: The power source that offers the most lateral flexibility works only on rails, which have the least need for it.
So grid-connected cars, if they run on tires, will need a power-supply system that supplies both current and ground from above – like the double-wire of trolleybuses. This is a fairly delicate technology even when all the drivers using it work for the transit agency, and even then the buses can’t pass each other. Will someone invent a system for grounding all of these private “trolley-cars” to the earth, maybe with some kind of continuous metal strip in the pavement that the car continues to touch? That would allow for zero lateral motion as well, so doesn’t really solve the problem. At times like these I’m so glad not to be an engineer!]
To sum up, I think we need to be reluctant to derive “PRT” from this path, because the result would be so unlike what anyone today means by PRT that we are only creating confusion by using the term.
I have delved on PRT because it’s a topic of interest on the blog, but the larger import of Gilbert and Perl’s book remains fascinating and timely. If the future lies in grid-connected vehicles, transit agencies should be getting out ahead by expanding trolleybus systems, and certainly not removing them.
Trolleybus infrastructure may be one of those investments that would make total sense in a world that correctly priced its carbon impacts, and other externalities. So long as the market is distorted, though, government simply has to override those market considerations in its own purchasing and planning decisions. Yet another reason that government, not just private industry, will need to drive this next “transport revolution.”
It's hard to pick much of a quarrel with the Environmental Defense Fund's new report Reinventing Transit, which invites us to admire 11 US "case studies" where a major mobility improvement has been achieved fast and affordably. The cases are:
We could disagree whether these are really the "top 11," but that's part of the point, just as it is in those lists of "top livable cities." By quarreling with the list we engage in the kind of thinking that the authors want to encourage. In this case, the goal is to inspire the general reader with the range of innovation occurring in the American transit industry. As the authors state:
Darrin Nordahl. My Kind of Transit: Rethinking Public Transportation in America. Center for American Places, 2008.
Like streets themselves, transit stations and vehicles are part of the common space of a city, and the experience of using them tells us a great deal, often at a crucial subconscious level, about our city and our place in it.
One of the great challenges of the transit business is to make every rider feel welcomed. It's easy to do this if you're running a few buses in a small town; there, you have so few riders that you can greet them all by name. But the challenge of big-city transit is to give a welcoming sensation to huge masses of people at once. The great cathedral-like train stations of American railroad era did this; many great European stations still do, and contemporary station design is finding its way back to those principles.