Chicago Goes Green in Its Alleys (1/2)

An environmental project in the American city of Chicago, Illinois, could offer ideas for cities around the world. The project is gaining ground -- and it is the ground itself that is involved.

Two years ago, the city's Transportation Department launched a program to improve surface wear and reduce flooding in alleyways. An alley is a narrow roadway through the middle of a block. The Green Alley program uses new technologies to help protect the environment, save energy and reduce heat in the city.

Chicago has three thousand kilometers of public alleys -- about thirteen thousand alleys in all. Many were built without connections to Chicago's combined sewer and storm water systems.

Alleys are being rebuilt or renewed with permeable pavement" class="hjdict" word="pavement" target=_blank>pavement. The material is hard enough to support the trucks that use the alleys to collect trash. But permeablepavement has openings that let water pass through the surface and into the soil below. Specially formulatedasphalt" class="hjdict" word="asphalt" target=_blank>asphalt, concrete" class="hjdict" word="concrete" target=_blank>concrete or pavers can be used. City officials say the material lets as much as eighty percent of rainwater pass through.