2008-7-13
This is the VOA Special English Development Report.
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. The material is hard enough to support the trucks that use the alleys to collect trash. But permeable pavement has openings that let water pass through the surface and into the soil below.
Specially formulated asphalt, concrete or pavers can be used. City officials say the material lets as much as eighty percent of rainwater pass through.
Also, sunlight bounces off the light-colored surface, so it stays cool on hot days. Densely built areas of cities trap heat. This is known as the urban heat-island effect.
The Green Alley program also uses recycled materials. And it uses energy-saving streetlights. These direct light downward to reduce light pollution at night.
Research for the project began in two thousand four. No businesses own any patents on the materials used in the Green Alley program.
Not all Chicago alleys need replacing. Program head Janet Attarian says sixty-two alleys will have been renewed or rebuilt by the end of this year. City officials are also starting to use the environmentally friendly technologies for parking areas and low-traffic roads.
Permeable pavement is not very good for roads with a lot of traffic. Too much weight and travel over the material can damage it.
Within six months of pouring Chicago's first permeable concrete alley, the cost of the new concrete had dropped more than sixty percent.
Chicago has "more miles of alleyways than any other city in the world," says Mayor Richard M. Daley in the Green Alley Handbook. We'll post a link to the program at testbig.com.
And that's the VOA Special English Development Report, written by Jill Moss.
This is the VOA Special English Development Report.