by Roxanne Warren, AIA

A Response to Ed Anderson’s various critiques of the Appendix to my book, The Urban Oasis (McGraw-Hill, 1997)

The debate about PRT between Anderson and myself hinges in the first place on the issue of density — whether medium to high densities can be made desirable, and whether such changes to our current land use would be beneficial or even possible within a free and democratic society.

Anderson sees PRT as a tool for making urban sprawl more workable. I see automation in transit as a potential instrument for both curbing and modifying sprawl, by creating, through targeted financial incentives, distinct channels of new, higher density, but landscaped, development within existing metropolitan areas — in order to absorb new population growth within existing cities and suburbs, and for this purpose, far simpler systems than PRT should be sufficient.

In other words, I see the primary issue as one of modifying our land use, before one can even consider what types of transportation technology are needed. The arguments for more compact development are not less compelling for their familiarity. They include:

our escalating per capita scale of consumption and paving-over of virgin and agricultural land; the consequent setting up of flooding conditions and interference with the recharging of underground aquifers; and the destruction of wildlife habitats;

our profligate consumption of fuel for motoring; its corresponding impacts on air quality, global warming, on our international relations and on our military policies;

our loss of walkable communities, and the resulting isolation of non-motorists and social alienation of our youth; and our increasing national problem of overweight and related ill health, much of which is attributable to a sedentary lifestyle.

Anderson notes that "The auto genie is (already) out of the bottle..." and remarks that "It is too late to worry now about how autos help or hurt our cities." I would beg to differ.

We are not helpless pawns in the face of urban sprawl. Humans have created sprawl, and humans can transform it, even at this late date. Nor is this pattern the "inevitable" result of free choice and the free market. It was, rather, the traditional city that resulted from the free market. The so-called Iron Law of Urban Decay is an artifact of political choice and not of nature. Sprawl could not have occurred in its present dimensions without the massive government and corporate-sponsored investments and subsidies that have encouraged private motoring, and a tax code in which an anti-urban bias has played a central role. The past and present influence of these investments and subsidies, and the potential for shifting our future financial support toward new priorities, cannot be dismissed in any discussion of the subject.

We erroneously equate private motoring with personal freedom, and assume that sprawl is the inevitable outcome of technological progress. But transportation facilities and investments in them have always been a central determinant of land use — far more important than zoning or codes. If moratoria were placed on the widening of roads and the construction of new ones on the urban fringe, sprawl could loose its momentum in a decade or so. If a region can control nothing else, re-orienting its priorities in transportation investments should still be an adequate tool to reform the use of land.


Anderson quotes Kenneth Orski that ".....the issue of sprawl does not energize the electorate (and that)’s the prospect of higher densities that brings out citizen opposition." In fact, the results of sprawl — the frustrations of traffic congestion and the loss of open land — are issues that are indeed energizing the electorate. This was witnessed by the results of over 200 ballot initiatives in the 1998 elections, in which voters across the country and across party lines passed multi-million dollar initiatives to protect open land, to establish urban growth boundaries, and to build mass transit in conjunction with incentives for denser, transit-oriented development. Even in Texas — where it used to be considered distinctly left-wing to oppose growth in a highly publicized statewide poll last year, more than half of the respondents named sprawl as a major concern.

The true test of these initiatives to curb urban sprawl will, of course, come as population growth forces the issue of density in each locale. The obstacles should not be underestimated; their pervasive nature suggests that, if more than mere lip service is to be paid toward curbing urban sprawl, we will need strong public initiatives and public interventions in the market, as has historically been the case with other non-profitable essentials such as education, health care, and basic urban infrastructure.


Real estate economics: The steam roller of sprawl is fueled by the fact that land speculation has, since the days of George Washington’s activities as a land surveyor in Virginia, been one of the most lucrative and politically protected undertakings of the powerful. There is the well-known "factor of five", by which the wholesale price of land beyond the urban fringe is commonly roughly quintupled as urban development approaches. When this land is furnished with infrastructural "improvements" (roads, sewer lines, water and electrical supplies) and with services, its value is further multiplied, again frequently by a factor of five. Speculators buy in anticipation of the extension of highways and utilities, or upon rezoning or subdivision, and willingly pay higher prices as soon as these events are committed.1

Augmenting factors: This potent stimulus to decentralization is reinforced by bidding wars for taxable businesses between states and municipalities, and by what can be called the spatial/environmental component of our car-culture. With conventional planning, which provides ubiquitous accommodations for automobiles immediately adjacent to buildings, the predominance of automobiles (which are some 25 times as voluminous as human beings) bring traffic congestion and paving of the environment as densities rise. The resulting inefficiencies and loss of greenery only encourage further migration to lower-density areas.

Land consumption, and the centrifugal momentum of urban sprawl: By 1970, our automobile-dependent development was already consuming some five to nine times as much land per person as was typical of societies from early Roman times until the advent of cars.2 Three decades later, the least populated of US counties are growing 60% faster than the most heavily populated counties, while converting nearly three times as much land per migrating household from rural to suburban use. As a result, we are depleting our farmland, forests and wildlife habitats at an unprecedented rate. We are losing irrevocably an estimated average of nearly 20 hectares (50 acres) of prime and unique farmland every hour, every day to suburban/ exurban development. If this rate continues, it is calculated that, by the year 2050, we will have lost 13% of our best farmland, and that by 2060 we could well become a net importer, rather than exporter of food.3

Continuing the trend: Typically, the migration of housing follows the migration of jobs, and in this respect the signs are not good for curbing urban sprawl. For example, despite the fact that the New York City area has by far the most extensive and best patronized public transit system in the US, its outer fringe of development — the newer suburbs and exurbs, where virtually every trip is by car — are projected to receive nearly half of the expected regional job growth over the next 20 years, if present land use trends continue. That will comprise an approximate 28% increase in the region’s jobs that will be totally dependent upon private motoring.4


Political/economic perspective: To artificially lower, through public policy, the cost of living and working on or outside the urban fringe, is an open invitation to the ever-increasing consumption of land and fuel for motoring to ever widely-dispersed destinations. And as the days of cheaply available petroleum draw to a close, our voracious appetite for this commodity makes it an ever more critical component of our economy and determinant of our foreign and military policy.

Ecological perspective: It was observed by Alexis DeTocqueville more than 150 years ago that the tremendous wealth and prosperity achievable on the North American continent were not derived from individual initiative alone, but depended for their base upon the endowment of an extraordinarily rich natural environment — the "exploitation of a boundless wilderness".5 It is only a little more than two centuries since we Americans began to avidly exploit this natural endowment. We are now faced with a choice of whether to protect or to further squander the richness that remains. The scaling back of our use of land need not, in fact, be viewed as a curtailment of our freedoms, but rather as a more reasoned and prudent husbanding of natural resources. For if we continue to degrade our environment at the present pace, we surely will degrade, and even devastate, the economic health and social order upon which these freedoms are based.

Sociological perspective: It has been argued that the cybernetic revolution now allows not only residences, but much employment to be located as remotely as an entrepreneur might wish. While this is clearly the case, it is equally certain that social seclusion is not a universally coveted state. With urban sprawl and the scattering of our population, we have been fulfilling a disturbing scenario that was presaged by deTocqueville — that of a society of households in space, isolated and alienated from one another — this is more true now in the US than at any other time in human history. With work stations more insular, there may be all the more reason why many individuals and families would opt for the sociabilities of higher-density, pedestrian-based, and walkable communities. These could dovetail with, and support vital societal needs, such as the need for less alienating environments for our youth, and less isolating conditions for our elderly.

Health negatives of automobile dependency: In addition to the air pollution and greenhouse gases generated, the side effects of the car-culture lifestyle on our general health could stand some scrutiny. American families living in automobile-dependent areas make an average of 10 trips per day by car, trips that are growing longer and taking larger percentages of peoples’ waking hours. One direct result is an enormous national problem with overweight among all ages, including more than one half of American adults, with associated problems of heart disease and an alarming recent escalation of diabetes, attributed by physicians as much to lack of exercise as to diet. The human animal was never designed for such a sedentary life. Perhaps there is some way that the costs of medical treatment for these illnesses could be factored into any cost/ benefit analyses of the relative benefits of new highways versus public transit systems with transit-oriented development.


But if democratic progress is to be made in combating urban sprawl, those factors which induce people to desert our cities and follow the developers to outlying areas must be explicitly examined and publicly discussed: As towns become cities and megacities, several basic elements become essential to their quality of life and fluid functioning. Speaking only of the physical environment (and over and above such exigencies as the need for adequate funding and upgrading of urban schools), the megacity’s neighborhoods and districts need to be interconnected via uncongested, and physically and financially accessible transportation systems. I know that this is the intent of the designers of PRT. However, there is another ingredient — one that is required to breathe health and beauty into the living environment — that of natural vegetation; its presence or absence can help define the very quality of a neighborhood and a city. It will not be enough to simply overlay the existing paved environment with a network of automated transit. In the absence of both of these vital components, the decline of our physical environment has preceded, and will continue to lead the way for the urban exodus and decline of socio/economic conditions in our cities.

Even if all of our cars were converted to fuel cell technology tomorrow, it would not solve the basic problem, which is one of space. Because of the very scale of the automobile, any program of relief from urban sprawl must begin with traffic restraints. As enclaves in the midst of surrounding automotive movement, communities and urban centers that are both environmentally benign and walkable will be key to retaining populations within already built-up areas.

There are two different types of traffic restraints that are already well-established — traffic calming for a wide range of densities, and downtown pedestrian zones. There is also a potential for a third type, which was the subject of my book,

1) Traffic calming is the very simplest and least expensive form of traffic restraint, and can be applied to a very wide range of densities, including the low-densities that characterize the majority of our existing residential development. Street networks are restructured to limit traffic in the neighborhood, with such devices as speed humps, culs-de-sac, planters, and neck-downs — all types of traffic being permitted, as long as they don’t exceed walking speed. But it is the pedestrian who has priority, while cars enter only as "guests". Traffic calming tends to be strongly supported by local residents; numerous projects worldwide over the past 20 years have amply demonstrated how, with very few resources, the simple act of detouring through-traffic can make a dramatic difference to a community’s environment and social solidarity.6

2) But as densities rise, as in downtowns, off-site parking and transit become all the more important. For humanizing our economically viable downtowns, we can look to European models of well-designed and maintained pedestrian zones, served by compatible transit such as light rail and/or underground metros. At least three components are necessary to ensure the success of such zones: a) an adequate number of pedestrians to populate the street, b) a high quality of design and maintenance of the public areas, and c) compatible and readily available public transit to and within the zone. The failure of a number of pedestrianized streets in the US has occurred due to the lack of one or more of these ingredients.7, 8, 9

When downtown pedestrian zones have been clearly conceived, incorporating these three elements, they have proven unexpectedly popular with respect to both expressed public reactions and to the very practical gauges of increased retail sales and property values. For example, commercial real estate on the auto-free streets of Cologne, Essen, Bremen, and Nürnberg is now considered prime property, and is virtually unattainable for purchase.10 In Florence, merchants who had originally opposed a plan for a 40-block auto-free "blue zone" subsequently favored it, and those who were located just outside the zone were pressing to have it enlarged to include them.11

Where light rail runs at-grade through pedestrian zones, it is generally limited to speeds of 30 km/hr to reduce the possibility of accidents. Amsterdam, Gothenburg, Strasbourg, Bremen, Heidelberg, Kassel, Linz, and Zürich are prime examples. Zürich’s Bahnhofstrasse has functioned over the past three decades as a prime, high-end shopping boulevard, with light rail running at-grade for its entire length and interfacing with regional rail of all kinds. Zürich’s citizens, including the merchants and real estate owners, voted this past spring (2000) to apply the same treatment to another of the city’s major shopping streets, and the negative vote was less than one percent.12

3) A need for a third type of traffic restraint—landscaped, APM-oriented development: In the US, urban sprawl and our vehicles miles traveled continue to increase, relative to population growth, at an accelerated rate, with our car population growing approximately twice as fast as the human population. At the same time, we have downtowns that are in serious decline and in need of "gut" rehabilitation, as well as vast, neglected urban acreage and brownfields on the fringes of our cities — all in serious need of redevelopment and revival. Surely a match is possible between the two. The objective should be to devise new models for accommodating this human growth within existing urban areas, rather than on virgin land, and without environmental blight.

The option of greening compact new development: Given our association of high-density development with paved landscapes and environmental blight, we need to be considering means of radically redefining compact development. What is explicitly needed is the pairing of 1) more effective local circulation systems to serve as integral links for access by pedestrians to longer-distance modes, whether these be rail or simply express bus systems; and 2) mixed-use, residentially-based development that, while incorporating higher densities, can be abundantly landscaped.

The very frequent and around-the-clock service capabilities of automated people movers (APMs) now open up possibilities for moving space-eating parking facilities to the peripheries of development clusters, to parking structures and/or ring road locations, creating either traffic-calmed or fully auto-free zones around the stations of APMs. Such a regrouping can, even for compact development, allow abundant landscaping, while convenient connected to the parking and to longer-distance transit.

Because the automation of APMs makes affordable their frequent service and around-the-clock operation, they can be especially effective armatures for auto-free development. Combining traffic restraints and landscaping with the ready accessibility of automation will create pockets of relief from both congestion and environmental blight.


Residential development as the major consumer of land and generator of trips: It is new housing, in particular, that consumes by far the largest share of land developed annually in the US — some 43%, according to the latest surveys (HUD, 2000). Therefore, if we are to conserve open land and ecosystems, an emphasis needs to be placed on creating new, compact development with a strong residential component. High-density commercial development is not enough.

Furthermore, since a) the great majority of all kinds of trips either begin or end at home, and since b) when a car is needed on either end of a trip, the natural tendency is to drive it all the way to one’s destination, and since c) certain minimal densities are required to justify the provision of regular, frequent and dependable public transit — it is in more compact residentially-based development that the key lies to the greater use of transit.

While Anderson advocates PRT as a solution for ".....vast, already-settled (currently automobile-dependent) portions of urban areas.....", it seems doubtful, indeed, that a sophisticated, automated guideway system could be afforded in (conventionally planned) areas which are sufficiently low-density to provide a truly green residential environment — or, indeed, that in such areas, an elevated guideway carrying a publicly accessible transit system would even be welcome.

The densities that I showed in my book ranged between 19 and 50 dwelling units per acre (47 and 124 units per hectare) for each cluster of development. Densities can vary considerably within the cluster, being more compact and transit-oriented at the station in the center, and more closely approaching our car-culture at the outskirts. A variation on this model would have parking for up to one half of the households located on a ring road.

Richly landscaped, basically auto-free APM-related TOD, or urban oases, would resolve some apparently conflicting factors:

The problems of access, congestion, and the walking environment at the suburban stations of regional rail: Because most passenger access to metros and commuter rail in the suburbs, particularly in the US, is by automobile, rather than on foot, the capacities of these costly systems are artificially limited by the capacities of their parking facilities and access roads. I would agree with Anderson that their resulting underuse puts an onus on even the relevance of regional rail. A train may be faster into the city than driving there through traffic, but only if you can easily get to the station.

There is also a collision of purpose between the need to build transit-oriented development (TOD) for regional transit networks and the need to provide ample parking facilities at these systems’ outlying stations in order to attract riders from surrounding low-density areas. The parking function, by exploding the scale of the station area and filling it with cars, blights it as a walking-and-living environment, making TOD there less desirable. So neither park-and-ride nor TOD is working optimally for transit. A series of APMs built as feeders to rail networks from landscaped urban oases would correct this problem.

Irrelevance of the New Urbanism to these concerns: Although it advocates TOD and walkable communities, the New Urbanism fails to dynamically engage these issues. The movement primarily addresses the public’s aversion to mega-scale and loss of community, while largely ignoring current issues of population growth, transportation complexities, and the fundamental changes that have occurred to the world’s statistical conditions. Humanity cannot retreat to a relative few select, nostalgic, pre-industrial-style villages. To imagine otherwise seems wishful thinking. Furthermore, notes author and urban journalist Alex Marshall:

The New Urbanists shun the label "suburban" and call their creations dug out of farm fields "urban". That these places, located miles from the center city, low in density, completely isolated, limited in their affordability, dependent upon the car, composed almost entirely of home owners and with few if any businesses, could be called urban is the height of absurdity. Even worse is the idea that they will help solve sprawl. They are sprawl. 13


Anderson remarks, in support of PRT’s small-sized vehicles, that "It does not take much experience riding in large-vehicle transit to note how deliberately most people avoid eye contact...(and that)...On city buses at late hours assault is a common occurrence. I have seen the data."

One might consider that, in the heyday of rail travel, transit was not less popular because its vehicles were shared with strangers. Surveys on the opinions of travelers need to be evaluated in terms of who is composing the questions, and who is answering them, before the data derived from them is taken at face value. As a non-city dweller, Anderson and other suburbanites/ exurbanites (who presumably include the female subjects of the studies to which he alludes) may well find themselves ill-at-ease in close proximity to other people, whether on transit or not. However, I can affirm that, as a city dweller, as a woman, and as a small person to boot, I am perfectly at ease taking mass transit, even in the evening, as long as it’s going through a safe neighborhood. And, declining to frequent unsafe neighborhoods, in 40 years of living in Manhattan I have never witnessed an assault on a bus. In other words, it’s the character of the neighborhood that matters, not the size of the vehicle.

Furthermore, while it is true that we who are regular transit riders do not, under most circumstances, make eye contact with our fellow passengers, this is not a matter of avoidance; rather, many of us look at our time on transit as a welcome, uninterrupted chance to read or do paperwork. Why should we intrude on others’ privacy, or they on ours? I suppose this reflects the old adage that one actually has more privacy in the city than in the suburbs. It’s a matter of choice, and whether one feels comfortable and friendly in the first place toward one’s fellow city-dwellers.

It is also worth noting that on Lille’s VAL system, where the VAL vehicles (which Anderson would consider quite large) have been operating in neighborhoods that were unsafe, these neighborhoods have actually become more safe since VAL’s operations began; no doubt, TV surveillance has been an effective component of this success.14 Nevertheless, this is a stellar example of courageous pro-city transportation investment decisions in "mass" transit that have had highly positive results.


1. Real Estate Research Corporation. 1974. The Costs of Sprawl: Environmental and Economic Costs of Alternative Residential Patterns at the Urban Fringe, Chapter VI: Land Cost Analysis, report prepared for the Council of Environmental Quality, the Office of Policy Development and Research, Department of Housing and Urban Development, and the Office of Planning and Management, Environmental Protection Agency, Washington, DC.

2. Pushkarev, B.S. and J.M. Zupan. 1977. Public Transportation and Land Use Policy. Bloomington: Indiana University Press. Regional Plan Association: pp. 4-7.

3. Sorensen, A.A., P.P. Greene and K. Russ. March 1997. Farming on the Edge, DeKalb, Illinois: American Farmland Trust, Northern Illinois Univ.: pp. 2-23.

4. Shore, W.B. April 15-19, 2000. Institute of Public Administration. Presentation, Session on International Perspectives on the Land Use/Transportation Connection, National Planning Conference of the American Planning Association, New York, NY. Information from The Four World Cities Transport Study: London, New York, Paris, Tokyo. Jan. 1999. Bernan, Lanham, MD.

5. DeTocqueville, Alexis. 1988. Democracy in America. First published in 1835. Translated from the 1848 edition by George Lawrence. Harper & Row Publishers, New York.

6. Institute for Community Design Analysis. 1994. "Improving the Viability of Two Dayton Communities: Five Oaks and Dunbar Manor." Great Neck, NY.

7. The Palisades Consulting Group, Inc., ITE Technical Committee 6A-47. September 1996. Final Draft Report: Update of Transit and Pedestrian Malls in 13 U.S. Cities: Table 6 - Project Effectiveness in Meeting Objectives. 24 Railroad Avenue, Suite 161, Tenefly, NJ 07670: p. 11.

8. Barnett, Jonathan. Spring, 1977. "What's New in Downtown Planning". Urban Design. RC Publications, Inc., New York.

9. Vizard, Mary McAleer. December 29, 1991. "Cars Trickle Back to Pedestrian Malls: Some Downtown Malls Are Coming Full Circle"; The New York Times, Sections 9 & 10: pp. 1 , 7.

10. Cobet, Hannelore. 26 October 1991. "Retail Development in Germany". Urban Land. Urban Land Institute, Washington, DC: pp. 25, 26.

11. TEST. May 1988. Quality Streets: How Traditional Urban Centers Benefit from Traffic Calming. Researched and published by TEST, 177 Arlington Road, London NW1, 7EY.

12. Discussion with Ruedi Ott, Head of Traffic Management (Leiter, Verkersplanning Zürich). 12 July 2000. Büro 224, Wermülestrasse 3, Zürich.

13. Marshall, Alex. May 10-11, 2000. "Wrestling the Beast Called Sprawl." Critics Talk About Smart Growth: Proceedings of a Colloquium on Reversing Sprawl/ Redefining Suburbs/Revitalizing Cities. Pocantico Conference Center, Sponsored by the Lincoln Institute of Land Policy in cooperation with the Institute for Urban Design, New York, NY.

14. Matra Transport International. June 1996. Field trip and briefing by Operations Department of VAL system, Lille, part of the 5th International Conference on Automated People Movers, Pairs, France.



Last modified: September 27, 2000