"Sprawl" is a term of American origin, which sums up a complex problem that threatens the long term viability of cities around the world. Sprawl is driven by the ubiquity of oil-based transport, but it is also the result of a century of disconnected, Cartesian thinking about cities—modernist thinking, which is increasingly discredited. In the last fifty years, office parks, business parks, residential culs-de-sac, superstores, hypermarkets and peripheral motorways have covered much of Europe and have become adaily experience of life.
     European planners and academics have long recognised sprawl development as a difficult issue, but so far little has been done and it is not high in the public consciousness. In the US by contrast, commentators¹ and organisations² have made continuous public attacks on sprawl, bringing it to the forefront of public debate. A broadly based group gathering planners, architects, developers, environmentalists and members of the public behind the banner of "new urbanism" has been working hard to develop practical solutions to the problem. The movement focuses on physical design and practical action supported by public involvement, and has made rapid progress, reaching nearly 5% of the very large US development market in its first decade. The movement's aim is to reduce the dependence on oil in the transport sector. It is neither nostalgic nor romantic, but based on a principled theoretical position. Let us first examine what we are building now.
     In the specialised world of modernist planning, shopping areas are separated from residential areas, residential areas from office parks, office parks from industrial estates, and so on. Traffic engineering rules prohibit the creation of interconnected networks. These patterns are supported by zoning in which industrial "pods"—the zones industrielles of France and the industrial estates of Britain—are separated physically from the places where people live. The net effect of these decisions—individually defensible from internally consistent criteria—is greatly to increase the number and length of trips required for daily life, whether on foot or by car.
     The origin of this relentless separation of uses can be traced, I believe, to the 19th century success in improving public health by technical means, starting with the separation of sewers and water supplies. This fed paranoia about cleanliness—"next to godliness" in the British aphorism—and about tidiness and order.
     Planning soon sought the authority implied in the rationalist and "scientific" approach. Experts began to define their areas of expertise, as generalisms withered. Analyses were made of residential density, traffic flows, healthiness and occupation, first as research and then as regulation. The various experts began to attempt to rationalise city form—the ultimate expression of the diversity and complexity of human life—into the simplistic terms possible with limited conceptual structures and crude controls.
     The emergence of large numbers of cars led to the discipline of traffic engineering, first in the US and Germany, and then elsewhere. Traffic engineers applied simplistic Cartesian thinking to problems of traffic flow across systems as complex as whole cities. The limitations of classical mathematics meant that the equations were basic. It was not possible to quantify flows on a sophisticated network, so the system was imagined as a series of self-contained pods. From analysis, it was a short step to planning over-simplified, diagrammatic road layouts. Traffic flows could be quantified, and that meant certainty in a litigious world.



CAR-DEPENDENT PLANNING is based on an assumption of oil use that is clearly unsupportable in the long term. The production of oil has now peaked and is expected to begin a gradual decline over the 21st century. Clearly, cities and regions dependent on the private car will be likely to suffer, as transport becomes increasingly expensive. Many low-income households in urban peripheries—out of walking range of services—which must own and maintain one or more cars in order to carry out their daily lives will be reduced to poverty.
     The dominance of car-dependent planning is revealed by current movement statistics, which show that the private car is the main means of transport in urban areas of Europe, although a much higher percentage of trips are made by walking and cycling than in the US. There is no single reason for this, but it must be assumed that the survival of walkable street networks in the centres of traditional European cities is a major reason. Unlike the blighted inner cities of the US, city centres in Europe are mostly well populated, if largely gentrified.
     Most development in the world today is suburban sprawl, or what is known in the US as conventional suburban development (CSD). This is not a natural response to freedom of choice—as some critics such as the ubiquitous Randall O'Toole of the Thoreau Institute would have it—but rather the result of a fragmented and regimented planning and construction process dominated by a technocratic expert culture of specialisms.
     CSD emerges in the absence of a clear consensus about future development. The process starts with developers buying up farmland in an accessible site, even if it is not zoned for development. In the US, sites near highway exits are commonly sought after, even when not contiguous with city boundaries. Planning typically begins with an environmental scientist designating which areas of land are to be reserved for the preservation of rare species and habitats. Next come traffic engineers following quasi-scientific requirements for smooth traffic flows and parking provisions based on worst-case scenarios established by statute on the basis of limited and dated research. Then follow land surveyors, who allocate the maximum number of minimal plots permitted according to residential zones established by planning regulation. Finally come the volume house builders, allocating designs to plots at random and following rules for front and side setback established by planning regulation, and providing car parking at rates either demanded by regulation or the market. In the US this means one car per occupant, and houses with a frontage entirely devoted to carports—so-called "snout-houses"—are commonplace. Office developers build the office park, at some remove from the housing, and commercial developers the industrial estate, similarly separated. The whole system is commonly funded by the managers of pension schemes, who have little interest in built product.
     In the CSD system, houses, offices, shops, factories and schools are all rigidly segregated with their own pattern of roads connected only to an arterial road. The rigid separation of uses and the dendritic street pattern produced, mans very long travel distances for the necessities of daily life. Most journeys are by car, as few people can be bothered walking the long distances created by the culs-de-sac and hierarchical road system, or through the dismal pedestrian environments typical of CSD. Parents (usually mothers) become taxi drivers for their offspring.



HOW CAN WE OVERTURN this massively entrenched system? Is it inevitable that our cities and towns become sprawl? Some architects and planners think not, and are drawing lessons from the structure of successful traditional cities.
     Much derives, I believe, from the urban conservation movement. Conservation is an idea with its origins in the earliest manifestations of Enlightenment pluralism. The architects of the Renaissance in Italy were sure that their buildings were superior to the Gothic. But seventeenth century Tory observers often lamented the modernisation of mediaeval houses, and by the 18th century a widespread reassessment of the value of ancient monuments was under way. In that period, coming full circle from the Renaissance, repair and maintenance of Gothic cathedrals was sometimes undertaken in a sympathetic rather than a contrasting style.
     The gathering pace of construction and redevelopment in the buoyant years after 1840 triggered others to consider the nature of interventions in historic cities. William Morris argued that:

It has been most truly said… that these old buildings do not belong to us only; that they have belonged to our forefathers and they will belong to our descendants unless we play them false. They are not in any sense our property, to do with as we like. We are only trustees for those who come after us.³

This was an important conceptual step, and it was greatly influential on attitudes to conservation. But it was also essentially a modernist view, and it suggested that an unbridgeable gap lay between "then" and "now."
     From 1882 legal status was given to designated ancient monuments in the UK, a procedure gradually emulated in other countries, at first only for buildings of great antiquity. War damage was repaired rather than rebuilt in most European cities in the early postwar years: conservation and reconstruction were one and the same. Even where widespread demolition and rebuilding were undertaken, important monuments were preserved. St Giles church was preserved in the centre of the Barbican in London of 1959-79 and the Marienkirche was marooned in Alexanderplatz in Berlin of c.1965. However, the appearance of these isolated buildings was soon seen to have been greatly diminished when stripped of their historic context.
     The Venice Charter of 1964, produced by the treaty organisation International Conference on Monuments and Sites (ICOMOS), was at the time a revolutionary commitment to conservation with which most countries chose to comply. In France, André Malraux began declaring whole towns as conservation zones. However, the Charter provisions included a requirement that there be a distinct junction between newly built and historic elements of a building. The clause was written with good intentions, but had unintended consequences on a huge scale. It was soon interpreted by modernist architects to mean that new buildings, and additions to listed buildings, should not harmonise or blend with existing buildings but should rather be designed to be a deliberate contrast.
     By the late 20th century, citizen activism against demolition and rebuilding on a large scale led by public demand to the replacement of the system of individual listings by a broader approach that emphasised the continuity of historic districts. This was a significant break with modern conceptions of the building as individual statement: now urban "fabric" was seen as a tissue composed of many contributing parts. The strength of opposition to modernist planning brought something of a crisis for architects. During the 1970s, the construction of groups of vaguely traditional buildings around retained monuments, as in the Nikolaiviertel of 1977-87 in Berlin, can be seen as a response to this crisis.
     Meanwhile, guidelines for the design of what became known as "infill" buildings in conservation areas directed architects to adopt alignments, heights, fenestration patterns, colours, materials and roof shapes of adjoining buildings. In many cities, detailed regulations required infill buildings to be deliberately bland, so as to emphasise the "genuine" historic buildings.



WORKING AS A government heritage advisor in the early 1990s, I was required to administer the Venice charter. Many applicants, having read the guidelines, would enthusiastically present a design that was a reasonable paraphrase of a traditional building. We had to tell them they were not permitted to match historical details, unless in simplified manner. Unsurprisingly, this drew a bemused response from applicants, who found it difficult to understand why, if existing buildings were so good as to have been listed, more of the same wouldn't also be good.
     For many architects, infill building was the first time they had been required to comply with urban design codes, and build to a defined envelope. Many found the experience a point of crisis, as it became clear that their efforts stood up poorly against their historic backgrounds. Some rebelled against what they saw as the strictures of context-sensitive design. Others took the context as a challenge, and put more time into studying the traditional architecture of their region. Many of this latter group began to question the relevance of their modernist teachings, and to become full-time traditional architects.
     For other architects and planners, such regulations represented an affront. Central to modernist architecture is a belief in the necessity of making an authentic statement of contemporaneity. Baudelaire defined the essential condition of modernity—modernism—as a self-conscious response to the ephemeral, the fleeting and the contingent: what Foucault later called "the 'heroic' aspect of the present moment." For Bauldelaide, Foucault wrote, modernity "is not a phenomenon of sensitivity to the fleeting present; it is the will to 'heroise' the present".⁴ The belief presupposes that traditional architecture is not a valid contemporary style, a view that I believe reflects a naïve and teleological view of the history of art and architecture. Certainly the demand for novelty became a burden to modernist architecture, as options for novelty were exhausted in the heavy mannerism of the 1970s.



POST-MODERNISM BROUGHT an epistemological critique of modernism that was situated outside this triangulation. To a postmodernist, modernist architecture itself is just another historical style, and not an inevitable response to the demands of contemporaneity. In the architecture of the late 1970s are visible the first architectural elements deliberately borrowed from the classical and other traditions. Initially elements were used with a mannerist attitude to rules of composition, as in the work of Venturi and Rauch, Rossi, Tigerman, Stirling and Farrell. Later, with the evident enthusiasm for the rediscovered language came more serious-minded works, of a type described by British architect Robert Adam as "literate continuity." This challenged the Venice charter idea of contrast in traditional cities.
     The attitude of "why not?" which infused the architecture of the late 1980s made the implicit "why?" of modernism seem hopelessly old-fashioned.⁵ At the same time, the Cartesian reductionism and Newtonian mathematics that that had supported modernism found themselves under attack from a new mathematics of complexity, which made possible the analysis of highly complex networks up to the scale of traditional cities. The new mathematics provides the theoretical understanding for the emergence of very complex but ordered structures built from a very limited number of simple "cells" or elements. This can be seen to explain the fractal nature of the traditional city, with its replications of self-same elements at a range of scales and its complex landscape built from the non-identical replication of simple elements. The traditional city, governed as it is by these simple yet complex structures, is seen by the mathematician and philosopher Nikos Salingaros to be a profoundly "natural" phenomenon, formed by quasi-biological processes. By contrast, the large-scale order of the modernist city is essentially non-living, what Salingaros calls "the geometry of death."⁶
     Interest in the reconstruction of the European city began with a series of theoretical projects published by the Krier brothers in the late 1970s. At the same time, Christopher Alexander's "A Pattern Language"⁷ of 1977—a profound reflection on traditional design—drew on studies of vernacular architecture and proved widely influential. The movement received encouragement in May 1984 from the Prince of Wales's speech to the 150th anniversary of the Royal Institute of British Architects. The trenchant criticism of modernist architecture that formed the core of the speech was widely reported around the globe. But the speech was made in the context of a much wider debate about the future of cities. It seems no coincidence that it was also the year in which Duany and Plater-Zyberk (DPZ, pronounced DeePeeZee) began work on the new Florida resort town of Seaside.⁸
     Andres Duany explained recently that his realisation of the value of traditional urbanism had come following a speech by Léon Krier. Duany was then working for Arquitectonica, a Miami architectural firm famous in the 1980s for its huge, brightly coloured apartment buildings⁹ featuring a variety of flamboyant motifs perhaps derived from the work of the Russian constructivists.¹⁰
     Duany recalls that he was at first outraged by Krier's insistence that modernism was worthless, then suffered agonies of doubt as he realised that his work to date had been, in Krier's terms, a waste of time. Shortly after this, Duany left the firm and with his wife Elizabeth Plater-Zyberk founded DPZ, an architectural and town planning firm based in Miami which has been highly influential.
     In the early 1980s, DPZ was approached by Robert Davis, a Florida developer whose family owned seafront land in the panhandle region, to build a new traditional holiday resort. DPZ suggested that they should draw upon the villages in the area, in which residents used open front verandahs as a respite from the heat of the evening, and walked barefoot to the beach on sandy paths running between the houses. The resulting development included a radial arrangement of streets around an octagonal central square, sandy walkways leading down to the beach between the houses, and a strict code to regulate construction and encourage a more open style of houses.
     DPZ's scheme included a dense mix of traditional detached houses and small apartment blocks on individual plots of land. Controlling the development was a series of strict design codes covering elements of the buildings from site coverage to proportion of windows. Driveways and garages were eliminated from the street frontage by the introduction of a system of rear access lanes. There was no stylistic constraint, and the seaside code permitted modernist buildings as well as traditional ones, provided that they met the detailed guidelines. Key buildings, however, were more strictly composed in a range of eclectic styles. As it developed, the project spawned many imitations including one in Coolum in Australia that even took the same name. A new adjoining development, "Watercolour," is currently under construction. Duany is philosophical about this, observing recently that successful resorts historically often form the nucleus of cities.
     Duany's idea was to codify the basis of Krier's European city project into a series of rules that could be applied by the middle-rank bureaucrats and building designers and thus affect the huge mass of building with which architects have little to do. The resulting planning documents include a comprehensive urban design masterplan, building design codes and pattern books. The approach has proved widely successful and the process is rapidly being refined and developed.
     On the west coast of the US, Peter Calthorpe's work on what he later called "transit-oriented developments" (TODs) set a paradigm of compact urban centres based around public transport stops (rail or tram) which was similarly influential. Some of these developments revive the grand urban geometries of the "city beautiful" movement originated by Chicago city planner Daniel Burnham, while others are more vernacular in feeling. Research into the developments constructed so far suggests that residents of TODs, while keeping their cars, make significantly more trips on foot.
     In the UK, the Duchy of Cornwall has since 1990 been building Poundbury, a significant extension to the county town of Dorchester, designed by Léon Krier and Alan Baxter Associates. Poundbury draws on the vernacular architecture of Dorset to produce a highly scenographic townscape at a density of at least double that of British CSD. More than 20% of the housing at Poundbury is for low-income families, rented from the Guinness Trust, and distributed indistinguishably among the housing for sale and for private rental. New houses in Poundbury sell at medium prices compared with similar developments in Dorchester. As in Seaside, parking is located behind dwellings and accessible from a back courtyard. The development uses clever street design to limit vehicle speeds to 20km/h without the need for intrusive signage.
     When Poundbury was first launched in 1992, it was ridiculed by the architectural press in the UK, because of the traditional style of the buildings. Every insult which could be ascribed to traditional architecture was brought out, as the project faltered in the slump of the mid 1990s. Since then, in an improved market, the development has proved a marked success. It was mentioned favourably in Richard Rogers' "urban renaissance" of 1999—though no illustrations were included—and has since been cited as a model development by the British government's planning authority, the office of the deputy prime minister (ODPM).
A key feature of all new traditional urban planning is the central involvement of the public through a participatory planning process known by the term "charrette." In a charrette, a team of architects and planners works directly with representatives of the local population, politicians and bureaucrats. Participants are encouraged to put pen to paper, with the aim of developing a binding plan. The technique has proved very successful at resolving complex and intractable conflicts between developers and local residents. It is also a useful way of developing public support for planning proposals. In the UK, the ODPM has recently recommended that all major new development include a charrette, or "enquiry by design" as it is termed in Britain. Design codes produced by such consultation are popular among residents, as they are an authentic means of citizen control and act as a check on neighbouring development. But they are often unpopular with commercial proprietors who see them as interference in private property rights.



IN THE EARLY 1990s, working with a small group of colleagues, DPZ began running conferences on urbanism. This new focus on city building was soon dubbed "new urbanism." In 1994, DPZ were part of the group that established the congress for the new urbanism (CNU). The CNU was founded around the charter for the new urbanism, a twelve-point programme for the re-establishment of urbanism in the United States.¹¹
     In Europe, the movement began to form in the emotionally charged development world of the mid 20th century, as dissatisfaction with destructive modernist interventions in historic cities crystallised in public protests. In Brussels from 1959, developer Charles Depauw and local politician Paul Vanden Boeynants began wholesale demolition of the historic Quartier Nord, intending to replace the traditional neighbourhood with Corbusian tower blocks and highways. The plan was widely condemned and the term "Bruxellisation" became the antonym of the movement for urban conservation. A similar proposal to level London's much-loved Covent Garden was defeated in 1968. Paris was not so lucky, and the soixante-huitards were unable to save Les Halles (demolished in August 1970) or prevent the construction of the hated east-west expressway on the banks of the Seine.



IN TRADITIONAL SETTLEMENTS, the buildings themselves define the roads. The reason for such compact development is clearly due to the high land values within walking distance of a town centre. Beyond this distance, land values fell to a level below which land was rarely fully developed. This is to be a feature of all human urbanism, defined by the distance people are prepared to walk on a regular basis, about 400 metres or a five minute walk.¹² Traditional cities tend to develop as a series of neighbourhoods or "urban quarters" of around 800 metres in diameter, or about 40 hectares. Studies of traditional cities around the world demonstrate the ubiquity of this pattern. The boundaries of neighbourhoods are not usually physically defined, but their centres—typically comprising a parish church, town hall, market, school and other public buildings—are usually found to be around 800m apart. This seems to be a relatively constant factor of human urbanism, defined by the limits of the body itself.
     New traditional urbanism seeks a return to urban form in which daily necessities are placed within walking distance of houses and offices, following this elemental principle. It is clear that a reasonable density is required to support such facilities. Similarly, an interconnected network of streets is necessary to minimise walking distances between all points in the urban quarter, as we cannot hope to predict where so many people will want to go. This is a seemingly obvious point, but one that is missed in the dendritic circulation patterns of CSD. These two elements—the 40 hectare neighbourhood and the interconnected network of streets—are fundamental elements of all new traditional urbanism. The "walking city" of new traditional urbanism is not a modernist fantasy of control, but a principle which gives dignity and mobility to people young and old, rich and poor.



THE SPRAWLING CAR-DEPENDANT CITIES developed in the post-war period can already be seen to be failing in economic terms in peripheral areas of Europe. The conurbation of Glasgow, for example, a shining paradigm of modernist planning—high rise towers in green parks, the last inner-city motorway programme in Europe, if not the world—has lost a third of its population in the last 30 years. The unwalkability and placelessness of car-dependent sprawl cities leaves them unable to attract the mobile young professional people considered important as generators of new economic activity. Conversely, those areas in which walkable street networks have been preserved have been able to survive for thousands of years. The new traditional urbanist principles of permeable street networks and neighbourhoods based on walkable dimensions can be successfully applied to solve many of the problems introduced into European cities by traffic engineering and planning based on zoning.¹³



SOLVING THE SPRAWL PROBLEM—which took most of the last century to create—will be a major issue for city and national governments in the coming century. We don't have a choice, as the world's oil is running out, and alternatives such as hydrogen fuel cells seem likely to prolong the system for only a limited time and at high cost. The principle of connectivity embodied in walkable networks, supported by a clear definition of private and public realm, provides maximum opportunity for the development of the range of individual paths and connections that are necessary to the development of individual lives.
     The problems facing cities around the world are self-evidently diverse, but the sustainability of all cities is threatened by the ubiquity of car-dependent sprawl development. European regions with strong industrial economies have become those with the ugliest landscapes of car-dependent sprawl. Here, regional economies are based on tightly knit groups of small companies, which rely almost without exception upon road transport for the delivery of goods and products. Their location in mono-functional sprawl requires most of their employees to drive to and from work.
     But the industrial era in Europe is already nearing and end. Northern England, Northern France, much of Belgium, the Ruhrgebeit in Germany and the industrial areas of Eastern Europe are already in severe difficulty. In the Veneto, the Po Valley, the Paris basin, the Netherlands, South-East England, the Alpine valleys of Switzerland, Austria, France and Italy, and around countless other European cities, sprawl landscapes are actively under construction. Cities shrinking in population are at the same time expanding in physical size.
     The future of sprawl Europe, with its disconnected street networks, car-dependency and unattractive places, seems very doubtful in the long term. The historic centres of European cities are robust and sustainable, as their great longevity makes clear, but 20th century damage to their walkable street networks will require careful repair if they are to survive. Conversely, the landscapes of the peripheries and areas with poorly performing economies—central France, parts of Spain, the west of England and Wales, the agricultural parts of Eastern Europe—retain compact settlements, coherent road networks and minimal urban sprawl, and have great potential for sustainable urban development in future.



TRADITIONAL URBANISM is a complex system of simple parts that can be combined to produce an infinite variety of urban places—and which can be easily replicated. It is so resilient and adaptable that traditional cities have been more or less continuously inhabited for some 2 millennia. It is straightforward enough to be simply taught, and simple enough to be understood and adapted by successive generations. Furthermore, the individual elements of traditional urbanism—the houses and buildings—are made of simple materials that, though not necessarily particularly durable, can be readily repaired with materials that are easily found or simply made and used over a period of thousands of years. Progressive modifications to small elements have not damaged the viability of the whole.
     There are encouraging signs of the re-establishment of urban life as an aspirational ideal among young people worldwide. This generation owes future generations a duty to build cities that will be as durable and sustainable as those we have inherited from the past.

MATTHEW HARDY
Dr Hardy holds a PhD in Architectural History from the University of Wales (1999) and a Bachelor of Architecture from the University of Adelaide (1980). He is an Alumnus of The Prince of Wales's Institute of Architecture (1994-1999).