The urban screens movement is bringing communities together with artistic as well as practical aims, writes Haydn Shaughnessy

In the 1991 modern classic movie LA Story, comedian Steve Martin, as weatherman Harris Telemacher, takes critical life advice from a temporary traffic sign . . . and why not? Stranded, roadside, by problems under the bonnet, Martin is guided in his quest to find his true self and real love by a lonely alphanumeric block whose normal job is to signal a road repair warning.

It could have inspired a generation of road signs to greatness but belatedly it may be about to spawn a new genre of urban art.

In the Zuidplein area of Amsterdam, which this week hosts a major international conference on art and urban screens, planners from around the world will discuss a variation on Steve Martin's theme.

In the Zuidplein, planners are about to open a virtual museum. Not exactly a talking traffic sign but a giant screen, 35 metres square, which will display regular everyday commercials like a billboard does but mix this with the digital display of artworks.

It is one of a growing number of ideas to integrate art with architecture and to re-colour urban space. Participants in the new urban screens movement, gathering to share experience, believe we are about to enter a new relationship with the visual environment.

Those of us who walk the city streets will not only find its hues and colours changed, we will also relate in new ways to each other.

Urban screens, the subject of the Amsterdam conference, with follow-up events already pencilled in for Berlin in 2006 and possibly New York in 2007, offer a new degree of flexibility in the physical appearance of cities and in the images that city and town dwellers share.

Whatever visions architects and planners may have had for urban areas, whatever failings they have suffered, for the best part of a century now the urban landscape has been dominated by commercial imagery, from the Pecan tipping at a Guinness bottle, to the neon Coca Cola sign to the ever-changing billboards tacked to the side of buildings, to fly posters, shop signs, special offers. Myriad images have assailed the eye but with one basic purpose. To sell.

The arrival of the digital screen, in theory, changes that. The commercial does not need an exclusive patch. Digital screens can be shared.

In a growing number of cities theory is fast growing into practice. In Paris and St Etienne in France, in Ankara, Chicago, Moscow, Melbourne, Manchester, Liverpool, Vilnius and Berlin, among others, new urban screen projects are under way, promising a kind of time-share on the digital billboard and our imaginations.

In Amsterdam's Zuidplein, the giant screen will be shared between local community users, art groups and commercial advertisements. The proportion of commercial images to artistic ones will be 20 per cent to 80 per cent.

Already planners in the city have mounted one extended digital art exhibition in collaboration with the Amsterdam Stedelijk Museum (city Museum), the private enterprise PARK4DTV, The One Minutes Stichting, UNICEF, the Sandberg Institute, and the Zuidas Virtual Museum, all organisations interested in promoting new uses of the billboard. However, all is not without difficulty.

"It introduces a huge question over how to curate," says Berlin-based Mirjam Struppek, organiser of this week's Urban Screen conference and a leading expert in urban media, a term that embraces not only images but also urban sound installations and what she calls "locative" art - art on the mobile phone.

"If you imagine 80 per cent of the time is art then you have to know what you want to show. In some cities like Berlin they opt for movies, for example, in the Postdammerplatz or in small venues where people can draw up a chair. If it's not movies then you need to answer questions about how to curate and that's the inspiration for the conference, to find out what is going on and to share ideas of how to use urban screens."

The renewal of the urban visual world is also inspired by the more technologically driven information spaces that we now inhabit, even involuntarily. Whether we like it or not, we are assailed by on-screen information. From parking advice to mobile text, in railway stations and on buses and trams, a frustrated weatherman like Harris Telemacher is today surrounded by possible guardian angels.

The suspicion is, though, according to planners such as Struppek, that their interventions are predominantly unromantic and uninspiring - practical, pragmatic and spell-checked, but in the end hardly uplifting.

There is a new potential, though, and that is for urban spaces to display more of the artistic vision currently housed in vaults or in institutions that spiritually belong to the arts and humanities graduate. In addition, modern technology, which guides us to work with geo-positioning satellites, and lands us at desks that we need not leave for the following eight hours, owes us more. It is demoralising as well as improving to work and live in such close proximity to the machine's will.

On the other hand, the presence of screens can change our perceptions and our behaviour. When the BBC placed 10 screens around Britain for a series of concerts back in the summer of 2002, the screens lay idle for a few days waiting for the technical team to remove them.

"But they took on a life of their own," says Bill Morris, a project director with BBC Live Events. "People came to us and asked would we mind if they showed a film on them. And then groups came to us and asked if they could post local information."

As a result the BBC decided to experiment with a giant screen in Exchange Square, Manchester, in collaboration with Manchester City Council.

"The result was more positive than we might ever had dreamt," says Morris. "We run content through the screens 24 hours a day now. Video, text, data news tickers, listings. In fact, the Arts Council commissioned a series of films especially for public screens and we've now exhibited the first few of those."

From the Manchester experiment screens have now gone up in Liverpool, Hull and Birmingham and more are due soon. Their uses continue to surprise the team involved. After the death of Ken Bigley, the Liverpool man murdered in Iraq, Liverpudlians came together for a two-minute silence. Hundreds turned up at the screen to commemorate Bigley's life. Some even laid flowers there. For an inexplicable reason the screen brought people together.

Unlike the Amsterdam experiment, the BBC excludes advertising from its projects. Instead the screens are viewed by the Corporation and the local authority as a new amenity as important as the local leisure centre or swimming pool.

"In 10 years' time there may well be a digital canvas at the heart of every community," says Morris, who also helped organise the screening of digital images of Britain taken by viewers.

Experience is beginning to show that even though the media world is fragmenting and that people consume screen-based information in ever more private ways, for example on their mobile phones and computers, there is a new and popular requirement to come together around screens, even in large numbers.

There are plans in a number of European cities now to use screens to allow audiences to interact, beginning with inter-city virtual golf tournaments and virtual soccer, and leading to who knows where. As people move away from the television and the hearth, they are moving in mysterious ways in the city streets.

Harris Telemacher could not have imagined that his roadside breakdown would eventually lead to a whole generation of people craning their necks as they pass through urban squares and boulevards and, like Steve Martin's character, asking the inevitable question of the big screen: "Are you talking to me?" A growing number of artists and communicators want to answer: yes.