SLIDESHOW: When bikes rule the big city's streets

Click to view in full screen. For about four hours last April 17, there was a massive traffic jam in the streets of Metro Manila. But unlike most traffic jams, this one didn't produce black fumes or consume a single drop of gasoline. And instead of honking horns, the only noise it made was that of ringing bells. It was traffic made up of thousands of bicycles. Last Sunday, thousands of cyclists gathered for the 13th Tour of the Fireflies -- Metro Manila's biggest fun bicycle ride. The event, which is organized every year by the non-profit organization The Firefly Brigade, aims to raise public awareness about the virtues of the bicycle-- an eco-friendly form of transport that some believe to be a viable solution to Metro Manila's worsening air pollution and traffic. Women, children, older people, and even a few superheroes joined the ride to show what the city might look like if bikes instead of cars ruled the roads. The images were contributed by the Firefly Brigade's volunteer photographers. Slideshow produced by Pia Faustino. -RSJ/YA, GMA News Online