Of bicycles and bipeds in Bogota. (Field Watch).

Enrique Penalosa's enthusiasm is contagious. When he began his three-year term in 1997 as mayor of Bogota, Colombia, the city was one of the most polluted and traffic-ensnarled in the world. Now that residents can ride their bicycles or take an innovative bus system to work, and enjoy more green public spaces, he travels worldwide with his message of making cities in developing countries more livable.

One of the tools he used to convince Bogota residents of the benefits of leaving their automobiles at home and taking public transport or riding a bike was the Car-free Day--an event organized with the help of non-governmental organizations (NGOs) and the United Nations, and their involvement together with local government is giving the movement for sustainable urban development and alternative transportation momentum, energy and direction.

A visiting Professor at New York University's Center of Latin American and Caribbean studies, Mr. Penalosa thinks cities in the developing world are at a critical moment when they can learn from the mistakes of industrialized nations and choose to develop in a more people-friendly way. He told the UN Chronicle that cities are "the most important places in the world--over the next thirty years there will be more than 2 billion people in cities" in the developing world.

"In order for these cities to prosper, they must provide happiness for their citizens", the former mayor said. "This happiness does not come from individual wealth, but quality of life. This is extremely crucial for the developing world because it is our competitive edge--we cannot give high income, but we can give quality of life", adding that this would enable the cities to retain their most educated citizens who might otherwise be tempted to move to developed countries where wages are much higher. He also said that one has to look at what wealthy people in developed countries do in their leisure time. "Maybe they like to take a walk in a park or ride a bike, or swim in an unpolluted river. Maybe we can achieve that in developing countries without being rich."

Reducing automobile use in cities is an effective way to provide a better quality of life for all citizens, said Mr. Penalosa, because it improves air quality and makes transport quicker and more efficient. Furthermore, public funds are not wasted on expensive road-building and maintenance programmes that only benefit car owners (a minority in the developing world), and they can be invested in improving public transport and bicycle paths, as well as public spaces.

"One of the most powerful instruments for creating an egalitarian society is by improving public space. A high-quality park never ceases to cause joy. People need to walk and be with people, and this is essential to their happiness. Parks, green spaces and libraries make enormous improvements for the lives of the poor and create a more just, egalitarian society." He said that he wanted to "create a city where people meet as equals. People from different parts of our highly hierarchical societies meet in public spaces, where, for instance, the apartment owner and the cleaning lady meet as equals. This deactivates a lot of tensions. If someone earns a million dollars a month but rides the subway, this creates a completely different kind of society."

This is more than just talk. As mayor, Mr. Penalosa limited private automobile use by 40 per cent during peak times, introduced a very efficient "surface subway" and a rapid bus transit system called Transmilenio, and laid 250 kilometres of bicycle paths (the longest network in the developing world). He also recuperated the city by constructing sidewalks where cars are not allowed to park, planted almost 70,000 trees, installed 183,651 planters, and greened 202 kilometres of roadside and 280 hectares of parks.

With the help of the United Nations and other NGOs, his Government held the world's largest car-free day. The entire city of 7 million people was closed to private automobiles, and residents used bicycles; buses and taxis to get to work and school. The event proved so popular that residents voted in a citywide referendum to hold it annually. "If I had asked them to have it once a month, they would have voted for it as well", said Mr. Penalosa.

You might ask yourself, "What is the use of one car-free day a year?" Ghazal Badiozamani of the UN Car-free Day Programme said the purpose is to start a dialogue and consider transportation alternatives. "A huge amount of momentum and awareness is created by the articles, editorials and discussions, and people begin to reflect on the long-term development of the city. This creates a mandate for action by city governments." She also said that car-free days are very effective because they focus on individual citizens' decision-making and "build community and a sense of ownership, giving people an opportunity to change their lives and the way the city is run. It is a symbolic act that can be very empowering. People begin to realize, 'oh, I can get to work riding a bus or bicycle', and that when the whole city does something, important things can get done."

Bogota's Car-free Day was so successful that other Colombian cities followed suit. In 2002, the event included a World Bank-sponsored seminar for mayors from other Latin American capitals, so that they could hold their own Car-free Days.

The Institute for Transportation and Development Policy (ITDP), a New York City-based NGO that promotes sustainable transport in cities around the world, has brought Mr. Penalosa to other countries as spokesperson for the movement. ITDP worked closely with the United Nations on the Committee for Sustainable Development 9--the last of a series of meetings that began in 1992 with the Earth Summit in Rio de Janeiro, Brazil and ended in 2002 with the World Summit on Sustainable Development in Johannesburg, South Africa. Oscar Diaz of ITDP said that "through the United Nations you can obtain important political goals that are necessary for sustainable transport", adding that it could play a key role in promoting sustainable transport by expanding the Car-free Day Programme and providing cities with resources to strengthen public transport and the use of bicycles.

This year's Car-free Day, held on 6 February, included an international seminar on human mobility organized by the Bogota-based NGO, Human City Foundation, in conjunction with the municipality, ITDP and the World Bank.

The 423 participants, which included mayors, ministers of transport and representatives from the United Nations and the World Bank, observed Bogota's innovative transport solutions firsthand, riding bicycles and the Transmilenio.

The Car-free Day, as Ms. Badiozamani said, stimulated discussion among the international participants about transport alternatives. Kleist Sykes, mayor of Dar-Es-Salaam, United Republic of Tanzania, said: "Until we have a decent, reliable public transport system, we cannot have a car-free day in our city." Paul Guitink of the World Bank praised the two mayors of Bogota, saying "Enrique Penalosa and [current mayor] Antanas Mockus have shown that you can make important changes with strong leadership". He also showed faith in Penalosa's vision for cities: "The presence of over thirty countries here is a testament to the fact that we can make cities for people and not for cars.