Public space in cities has become a battleground for this century. Environment Editor Frank McDonald visits Copenhagen, where it's safe to stroll and cycle

What do we mean by public space? For most people, it would be a park or a square, a new civic plaza or a promenade. But the truth is that at least four-fifths of all public space in any city consists of its streets. And how we apportion their use says a lot about our urban sensibilities.

It's no coincidence that a conference this month on Public Spaces, Public Life was held in Copenhagen.

The Danish capital was the first to introduce the concept of a pedestrian street way back in 1962. Since then, Stroget - literally "strolling street" - has become a template for many others all over the world.

The Danes have built on the 1.5km-long Stroget by extending it into adjoining streets as well as creating a seamless network of generously wide cycleways throughout the urban area. It's no wonder that Copenhagen is Europe's foremost "bike city", with a staggering 36 per cent of all commuters cycling to work.

Very few wear helmets; they don't need to, because cycling is quite safe there. Similarly, pedestrians don't have to wait endlessly on footpaths; at most crossings, they get the same amount of time as the traffic (30 seconds each). At College Street in Dublin, it's eight seconds for pedestrians and 96 seconds for traffic.

Copenhagen won the title European City of the Year from the Royal Institute of British Architects in 2005 primarily because it is a "people-dominated city", according to former RIBA president George Ferguson.

The city council even has a department of pedestrians, public spaces and public life, and an action plan to pursue.

The plan, adopted last year, aims to further improve conditions for pedestrians, making the city accessible to all, as well as creating more spaces for playgrounds and leisure activities, such as the new promenade fringing the edge of an artificial island and lagoon on the Oresund, with 12 wind turbines offshore.

But then, Copenhagen is remarkably civilised. It has none of Dublin's traffic congestion, or any sign of road rage; in five days, I heard one car driver honking his horn.

Another remarkable thing is that there isn't a single European flag flying from any public building. That's shows their independent-minded, Scandinavian streak.

Jan Gehl, the Copenhagen-based veteran architect and urban designer, was the first to draw attention to the whole issue of public space in the city in his influential book, Life Between Buildings, published in 1971. He still firmly believes that cities need to be "re-conquered" to roll back the invasion of cars.

"If we want more sustainable cities, we need public realm, public transport and people living closer together", he said. "As we get older, we'll have more time, so there will be more need for meeting fellow citizens, of all age groups. And to meet face-to-face and smile to each other makes for a much safer society."

The primary function of public space is as a meeting place, he told the conference. "Some awful spaces are still being made because there are quite a few architects who never found out what it's all about. Others are being made with great care because we're getting better at it, but we really need to understand the issues."

According to Oslo-based architect Peter Butenschon, public space is "the central battleground of our civilisation" and he wondered why it was not so hotly debated as "opera houses, motorways and the secret life of celebrities". Maybe, he speculated, "it seems too polite, something nice to have when you can afford it".

The issue of public space needed to be "politicised", as the first thing any dictatorship does is to ban the right to demonstrate. "We also need to battle against the perfect architectural project, with slick spaces that contain culture," he said, citing the Casa da Musica in Porto by Rem Koolhaas as one overblown example.

Fred Kent, a New York-based consultant, told the conference that the movement to recreate public space as a "dynamic human function, the essence of true democracy" was now a worldwide one. And he defined place-making as "turning somewhere from a place you can't wait to get through to one you never want to leave".

He himself has been involved in the transformation of Bryant Park in New York from a drug-dealing enclave into "one of the city's great gathering places". He also cited Rockefeller Center as a once sterile place which had now become a fun venue for events and exhibitions, a "town square for New York City and the US".

More dramatic, because it's city-wide rather than "acupuncturist" in approach, is the transformation of "dead and deserted" Melbourne into Australia's "most interesting and vibrant city" - in the words of Rob Adams, the South African-born architect who has been working on it for 20 years and is now its "director of design and culture".

His mission, outlined in a 1985 strategic plan, was to turn Melbourne's central business district into a "central activities district" by creating good places to live and making it both financially viable and environmentally sustainable.

"If we can design good streets, we will have good cities" is his simple motto - and it clearly works.

Nearly 10,000 new apartments have been provided in recent years, streets are alive with new shops and outdoor cafes, there are 75 festivals a year and the city has a major public art programme, including the "Travellers" memorial to Australia's waves of migration - giant stainless steel sculptures that move across a bridge.

One of Adams' proudest boasts is that Melbourne has "taken out 20 hectares [ 48 acres] of asphalt", in the form of roads and freeways. A new levy on inner city commuter parking will raise 19 million Australian dollars (€11.2million) in 2006 and twice as much again next year to fund transport initiatives, including bus and cycle lanes.

Any city can have plans, but they're only good if they produce results.

Equally, as Steffan Gulmann told the conference, international branding is fine as far as it goes - but a city must live up to its "brand image".

The vision must also be effectively communicated to the citizens, so that everyone is given a chance to buy into it.

Landscape architect Stig Andersson emphasised that urban public spaces must offer "texture, colour and sensuousness" - giving people different experiences as they move through the city, by day and by night; a public life survey in Copenhagen last year showed that a third of all activities in the city are happening at night.

Even though Dublin is teeming both day and night, we still don't have a concept of public space, and not much of an idea about what to do with it.