Architecture: Imagine towns of beauty, it's easy if you try: Richard MacCormac says urban designers need a vision of how places could be - and teamwork to achieve it

LOCAL and central government need to take a fresh approach to change and development in our towns and cities. 'Urban Design in Action', a new exhibition at the Royal Institute of British Architects, explains what is needed and why.

Few architects are blind or deaf to the dismay the public feels at what it perceives as thoughtless and rapacious changes in its surroundings. Forty years of traffic engineering have helped destroy the familiar order of towns and cities by pushing highways through the middle of them. On either side of these roads, huge buildings have risen: incongruous islands in a no man's land of useless space.

Yet consider Birmingham, which used to be a city dedicated to highways - given over to people who wanted to be somewhere else. Today, by reviving the sense of what it is like to experience civic space, Birmingham has begun to restore the experience of what it is to be a citizen.

Centenary and Victoria squares are being transformed through design, landscaping and the integration of art and architecture, and linked by a lively pedestrian network. Birmingham recognises that highway engineering, so often answerable only to itself, has to be subsumed into the disciplines of planning, architecture and landscape.

To blame the damage done to our cities in the name of development solely on 'modern architecture' is to miss the point that there is no machinery for collaboration between planners, traffic engineers and architects to create an overview of a locality. Decisions are taken piecemeal. The result is a fragmented environment. In an attempt to demonstrate how such fragmentation can be overcome, Riba has explored the nature of urban design in its 'Vision For Britain' programme, which has held weekend workshops in 18 cities, including Glasgow, Birmingham, Liverpool and Cambridge.

Each has studied sites within the host city and brought together architects, landscape designers, engineers, artists, residents, businesses and councillors. Practical and visionary proposals for highly complex situations have been made with surprising speed, quite unlike the realities of local government.

A successful urban environment can only arise if it is shaped by an imaginative collective vision, but collective thinking does not seem to appeal to the Government. With its doctrine of unrestricted freedom in commerce, it lost faith in visionary planning and in so doing it has encouraged chaos, such as we see in London's Docklands.

It was not all chaos in the Eighties. Enlightened private development brought commercial estates into being, including Stockley Park at Heathrow and Broadgate in the City of London. These echo the ethos of coherent urban design demonstrated by the great 18th-century London developments, such as the Bedford Estate in Bloomsbury. The lesson is that individual commercial buildings should be designed as parts of a whole. And the 'whole' includes the public space in which the buildings are set.

These exemplary private developments were possible because the developers owned areas of land large enough to be built up as complete 'localities'. These same people also recognised that skilful urban design provides aesthetic gain, which translates into added commercial value for the property.

The architectural debate about cities has concentrated too much on style, and a false opposition has been set up between architecture of the past and the present. Urban design can include stylistic prescriptions, but its primary function is to create good places rather than control the appearance of individual buildings. Done properly, an urban design analysis of an area establishes fundamental conventions for architects to follow that are based on observations of the way cities have traditionally been organised.

Think, for example, of a cross-section through the Thames that continues through the Savoy Hotel and then across the Strand, Maiden Lane, Covent Garden, Floral Street and Long Acre. The Thames has the symmetry of great public and private buildings of symbolic power facing each other across the river. The Savoy looks out to the river as one of these powerful buildings, but on the side facing away from the river, the scale is different. The Savoy becomes part of the pattern of the street with the shops, restaurants and other buildings typical of the Strand. The scale then falls away to the flats and chambers of Maiden Lane and rises again with the symmetry of Covent Garden. The scale and intensity subsides in Floral Street only to rise again in Long Acre.

In all of this there is richness and complexity; it is a form of urban ecology entirely lacking in monolithic developments such as those that have taken place in Docklands or in other swathes of urban modernisation. Too many modern buildings monopolise whole blocks with a single function, and provide the same frontage on all sides, regardless of the scale of the streets that bound them.

Urban design offers a critical process for quickly evaluating planning policies and the ambitions of developers. It examines three- dimensional consequences before detailed design is undertaken. In this way, it is possible to pre-empt time-consuming and expensive confrontation.

Information and ideas provided by urban design studies can be explained by drawings, models, videos and computer images. Such tools can convey the experience of walking through a new development before it is built. The ideal of urban design - the harnessing of collective public aspirations for a town, city or locality - will remain elusive until local government uses its powers to apply urban design analysis. The creativity and vision to resolve the effects of urban change exist, but are stranded in a political vacuum.

The author concludes his two years as president of Riba this month.

(Photographs omitted)