With humor, education, and tough laws, this Colombian city has dramatically reduced traffic injuries and deaths
Long branded as one of the world's most dangerous cities, Bogotá, Colombia, has won plaudits for cutting its murder rate by more than 70% during the past decade. But this city of 7 million people has received far less attention for a dramatic decline in a more common danger that plagues urban areas everywhere: traffic-related injuries and deaths.

With a combination of innovative education campaigns, an overhaul of its public transportation system, strict law enforcement, and redesign of streets and highways, Bogotá has made moving from place to place safer and more efficient. "In 1997, everything was a mess and we were losing the battle," says Dario Hildalgo, a transportation engineer from Bogotá who is now with the World Resources Institute in Washington, D.C. "To solve the problems, we needed a miracle. The miracle happened."

Mark Rosenberg, the former head of injury prevention at the U.S. Centers for Disease Control and Prevention in Atlanta, Georgia, says Bogotá is a model for the world. "Bogotá is not unique in having this problem, but it is unique in solving it," says Rosenberg, who now heads the nonprofit Task Force for Child Survival and Development in Decatur, Georgia.

On a clear, cloudless afternoon, Enrique Peñalosa, former mayor of Bogota, leaves his office early in order to pick up his 10-year-old son from school. As usual, he wears his black leather shoes and pinstriped trousers. As usual, he is joined by his two pistol-packing bodyguards. And, as usual, he travels not in the armoured SUV typical of most public figures in Colombia, but on a knobby-tired mountain bike.

Mr. Peñalosa pedals through the streets of Santa Barbara in Bogota's well-to-do north side. He jumps curbs and potholes, riding one-handed, weaving across the pavement, barking into his cellphone with barely a thought for the city's notoriously aggressive drivers.

On most days, this would be a radical and perhaps suicidal act. But today is special.

Ever since citizens voted to make it an annual affair in 2000, private cars have been banned entirely from this city of nearly eight million every Feb. 1. On Dia Sin Carro, Car Free Day, the roar of traffic subsides and the toxic haze thins. Buses are jam-packed and taxis hard to come by, but hundreds of thousands of people have followed Mr. Peñalosa's example and hit the streets under their own steam.