The aim of European Car-Free Day, which is having its Irish manifestation tomorrow, is to promote awareness and debate about the future form of urban transport.
It is widely supported, but inadequate public transport, notably in Dublin, has led some to claim many people will simply be stranded by lack of an alternative means of transport - and surrounding streets will be choked even more than usual.
Earlier this year, the Minister for the Environment, Mr Dempsey, signed the European CarFree Day charter, pledging the Government's commitment to the idea. Local authorities in Dublin, Galway, Cork, Limerick and Portlaoise will be responsible for organising their car-free days with the support of the Irish Energy Centre.
European Car-Free Day emerged from an initiative begun in France in 1998, En Ville Sans Ma Voiture (in town without my car). It was part of a series of measures taken by the French government to deal with air pollution in large cities.
Research on the success of carfree days in France and in carmad Italy, where rates of car ownership are among the highest in Europe, indicates a dramatic change of attitude in favour of making central districts permanently off-limits to traffic. Although Dublin is taking part, Dublin Corporation has watered down the concept by blocking the city centre to cars only during off-peak hours.
The corporation's director of traffic, Mr Owen Keegan, said the authority was very judicious in terms of restrictions put in place; it was not stopping people from coming in by car on the day if they wanted to.
"The novelty of having car-free streets will appeal to an awful lot of people. While some may be inconvenienced, I don't think we should forget there are a lot of people walking around the city who, on a daily basis, have to put up with the negative impact of car traffic."
Mr Conor Faughnan, a spokesman for the AA, welcomed the plan to block off the city centre to cars only during the off-peak period as "a highly sensible concession to practicality", which contrasted with the European Commission's desire that cities would block cars from centres throughout day.
The sub-text of the car-free day, however, was to shame motorists into believing that if it were not for the use of their cars the city would be a better place, he said. "I think that's a terrible message to send to people who are trapped in their cars for want of a better alternative."
Mr Pat Delaney, director of the Small Firms' Association, said the car-free plans did not take into account the concerns of business. "From a social perspective, it's a good thing. From an economic perspective, it's madness."
Fine Gael's national road traffic spokeswoman, Ms Olivia Mitchell, described the day as "nonsensical" and called for it to be scrapped until there was a proper public transport system in place. "There is no synchronising of increased public transport supply with increased disincentives to use the private motor car."
A spokesman for Galway Corporation said while there were plans to close off areas of the city centre to private cars, they were not going to be too draconian. However, he was confident the initiative would be welcomed by citizens, judging from the positive response to pedestrianisation of areas of the city.
Mr Brian Motherway of the Irish Energy Centre said the main objective of the day was to allow people to experience a car-free urban environment for a few hours and to stimulate debate about the future of urban transport.
Emphasising the experimental nature of the event, he was nonetheless confident that any concerns about disruption would be assuaged by what was being done to provide alternative transport. He noted Galway Corporation was laying on park-and-ride facilities for the day.
"Obviously the system is not in place for a permanent change from cars to public transport, but the more debate there is about the issue, the smoother the transition will be."