Cities have become socially divisive and environmentally hazardous. And if we in Britain think that our problems of pollution, congestion and inner-city decay are appalling, look at the massive changes that are overwhelming the cities of the developing world.
In 1990, of the 35 cities with populations over 5 million, 22 were in the developing world. By the year 2000 the number of cities in the developing worldwill double. Two billion people are expected to be added to the urban population of the developing world within 30 years. And this, even though at least half of the new urban population will be living in shanty towns with no running water, no electricity, no sanitation and no hope.
I have highlighted some of the environmental problems our cities are now facing. But what also needs to be stressed is that social and environmental issues are not distinct. Strategies to improve the sustainability of our environment can fundamentally improve the social life of our cities. Sustainability means healthier, livelier and more open-minded cities. The key to making cities more sustainable lies, in my view, in reinterpreting - re-inventing the dense and diverse urban city.
It is worth remembering why dense cities went out of favour. The industrial cities of the 19th century were hell. They suffered extremes of over-crowding, poverty and ill-health. Foul-smelling open sewers meant cholera and typhoid. Life expectancy in many cities was less than 20 years. Lack of housing meant you could find families living 10 to a room. The majority of the population scarcely had any access to parks so ordinary people needed to get out of the city just to breathe fresh air. It was in the face of these inequities that planners proposed decanting populations into less dense, greener surroundings - Garden Cities and New Towns.
Today, with heavy industry already gone from developed cities, with coal- burning banished, with state-of-the-art public transport systems and virtually clean power generation available, the dense city - at least theoretically - is no longer a health hazard. This means we can reconsider the case for close-proximity living. We should be reinvesting in the idea of a dense and socially diverse city - shaping cities into compact forms and focusing communities around lively neighbourhoods. Yet today, the clich of the North American city - downtown office zones, out-of-town shopping malls, housing ghettoes and residential suburbs, all linked by polluting and socially divisive highways - is still the dominating "urban image" worldwide.
There are a number of factors motivating the expansion of the city and the segregation of its activities. Even on the small scale, builders are turning their backs on mixed-use building. These buildings, in which studios sit over family homes, which sit over offices, which sit over shops, bring life to streets and reduce the need to drive for every daily need. But these create complex tenancies which local authorities find hard to manage and developers hard to sell. Both prefer big open sites where they can construct whole housing estates or business parks, with minimal planning restrictions and maximum standardisation.
The second destroyer of communal life in the city is the car. Just as the elevator made the skyscraper possible, so the car has enabled citizens to drive away from polluted city centres, and has made viable the whole concept of dividing our everyday activities into segregated zones of offices, shops and homes. As cities spread out, it becomes uneconomic to expand public transport systems, and they therefore fail to provide an adequate alternative to driving.
The car is perhaps the century's most liberating technological product. On the face of it, the car is cheap, practical and promises freedom and status. Simple logistics show how increasing car ownership transforms the city. Public space is taken over by parked cars. An efficient parking standard requires 20 square metres for a single car. If only one in 10 citizens owns a car, in a city of 10 million people, you need an area twice the size of central London, just to park their cars. Start up those million cars, and drive off, and you saturate the city with pollution and congestion. Just the anticipation of high levels of car use has made city planners design new cities around road specifications, ignoring most other human needs. The tail is wagging the dog.
The new form of dense and diverse city is the Compact City. The first benefit of the compact approach is that the countryside is protected from the encroachment of urban development. For the citizen living in the city the compactness is relieved by a network of public spaces and parks. The Compact City would grow around centres of social and commercial activity. London's historic structure of towns, villages and parks is typical of this polycentric pattern of development - a social structure which focuses communities around neighbourhoods.
These neighbourhoods would include a diversity of private activities and bring public services, including education and public transport as well as local work opportunities within convenient reach of the community. This proximity would reduce the need for driving for everyday needs, and make trams, light rail, electric buses, cycling and walking more pleasant and more effective. It would also increase conviviality, and restore the natural policing of streets by an increased presence of people and decreased congestion and pollution from cars.
Proximity and the consequent reduction in congestion, the presence of landscape and the exploitation of new urban technologies can radically improve air quality in the city. The concentration of buildings can make for more efficient distribution of power.
Sustainable cities of this sort could, I contend, reassert the city as the physical embodiment of a community-based society.
In 1991 my practice was invited by the Shanghai authorities to propose a strategic framework for a new district of the city. This offered us the chance to explore and apply the principles of the Compact City.
Traditionally Chinese cities and their agricultural hinterland were considered an interdependent totality. Even today Shanghai is nearly self-sufficient in vegetables and grain. But in the rush to industrialise and urbanise, the ecology has suffered. Five of the world's 10 most air-polluted cities are in China, four of China's seven most important river systems are contaminated and acid rain has spread to 29 per cent of China's territory.
In 1990 Shanghai, the world's fifth largest city, had a population of 13 million. In five years it will have more than 17 million. The city's ambition is to consolidate its role as the principle commercial centre of China and a major force in world finance. To do so the authorities intend to follow the Western model, expanding the city and motorising the 7 million or so cyclists who fill the already crowded streets.
Shanghai opens on to the famous tree-lined riverside of the Bund - it is a waterside to rival the elegance of the Promenade des Anglais in Nice or the power of Liverpool's great river frontage. The Bund has been the first casualty in the drive to convert the city to accommodate more motor cars. Watching the lines of mature trees being chainsawed to be replaced by a continuous two-storey car park (on the very edge of the river) I was filled with a deep sense of foreboding.
The Huangpo river is almost a kilometre wide and crisscrossed by merchant shipping. Beyond the river is the Pudong, a vast expanse of land covering thousands of hectares and immediately opposite the heart of old Shanghai is the site of the new district - a teardrop shaped, 1km square site, of remarkable similarity to London's Isle of Dogs. Intended as a pure office development for 500,000 workers, the new district has been envisaged as a Canary Wharf-type development but over 10 times larger.
The development proposed by the Shanghai authorities turned its back on the diversity of the old city. The new district was aimed at international office users and planned around the car. The local traffic engineers planned for intense rush hours which meant massive roads, sometimes double - and triple-decked and a network of pedestrian underpasses and bridges. So dominating were the roads that only one-third of the site was left for buildings - an average road coverage three times greater than that of New York with less than half as much building. And with each building isolated by highways, the result would be a district of stand-alone individual skyscrapers surrounded by acres of cars: socially and environmentally unsustainable in every aspect of its design.
By contrast, our approach was to create not a financial ghetto separated from the life of the city but a vibrant, mixed, commercial and residential quarter capable of acting as a focus for the whole Pudong, and of driving its economy. This approach also avoids vulnerability to the boom-bust cycle of the international office market, which bankrupted single-function developments such as Canary Wharf. Most fundamentally we aimed at establishing an environmentally sustainable community.
Our transport engineers calculated that with a broader mix of activities, and a greater emphasis on public transport the area taken up by roads could be reduced by as much as 60 per cent. Air pollution was dramatically reduced and we were able to transform single-use roads into multi-use public space - vastly expanding the network of pedestrian-biased streets, cycle paths, market places, avenues and making possible a substantial central park. These public spaces were carefully linked to create a single interconnected web of movement. The overall aim was to locate the community's everyday needs including public transport within comfortable walking distance and away from through traffic.
Woven into the public domain and focused on the six main transport interchanges were the neighbourhoods, each with a different character and all within 10 to 15 minutes' walk of the park and an adjoining neighbourhood. Predominantly commercial offices and retail were located closer to the busy underground stations.
With less need for road space, buildings could be joined together to form streets and squares. By varying the heights of buildings we could optimise daylight into buildings and focus sunlight into the streets, squares and avenues. The result was a city profile crowned by a series of towers.
Whether Shanghai itself will pursue any of these proposals is an open question. Political and commercial pressures have already led to the sale of isolated sites. And the highest building in the East is to be erected in the very centre of our unbuilt park. This will lead to the construction of roads to service the new buildings and will generate the classic market- driven form of the modern commercial city.
Yet for a huge number of the world's new urban dwellers, the shanty town is their first and usually only experience of modern city life.
Shanty settlements, which are normally illegal, in some cases house as much as 75 per cent of a city's population and these shanty towns mostly lack even the most rudimentary services such as drainage, electricity and clean water. In Bombay 5 million people - the population of inner London - are shanty dwellers. Yet in some rare cases squatters have displayed a degree of social cohesiveness and resourcefulness and have created viable low-cost towns. It is now widely accepted that - in the absence of a fairer distribution of wealth - the best way of helping squatter settlements is to encourage self-help and to provide vision and technical support.
There are success stories. Curitiba, in south-east Brazil, once a desperate shanty town but now a vibrant city with more than 2 million residents, has made self-reliance the spirit of its daily life and environmental sustainability is its top priority. Recycling has become an integral part of the Curitiban lifestyle - the parks are lit with lamps made from Fanta soda bottles, and domestic garbage is handed in to central refuse yards in exchange for fresh vegetables. The town was once covered in festering garbage. It is now planned around a network of parks and squares. Twenty years ago Curitiba had half a square metre of open space per citizen, today it has 100 times more. Clearly the extraordinary problems that shanty towns face must be primarily tackled from within the community.
Cities have become parasitic additions to the landscape - huge organisms drawing their sustenance from the world over, relentless consumers, relentless polluters. In the beginning we built cities to overcome our environment. In the future we must build cities to nurture it.Reuse content