A new initiative will help make Chicago’s 1,900 miles (3,000 kilometers) of alleyways more sustainable. The miniature streets behind homes and buildings, used mainly for garbage collection and parking access, keep main roads cleaner and less congested but are prone to flooding. The cityâ€™s innovative Green Alley Program promotes improved construction techniques and materials that can improve drainage, reduce runoff, and relieve strain on the cityâ€™s aging sewer system. Model “green” alleyways in Chicago have been re-surfaced with permeable or porous pavement, a relatively new technology that allows water to seep through asphalt, concrete, stone, or plastic.
After filtering through a stone bed, the water can then recharge local water tables, instead of becoming polluted runoff that flows off the road into streams and rivers. The new alley surfaces are made with recycled material and light-colored pavement that reflects heat, keeping them cool on hot days and reducing the “urban heat effect.” The alleys also use energy-saving overhead lighting that directs light downward to minimize light pollution.