Chicago’s Green Alley program is an environmentally friendly initiative to reconstruct alleys, creating a greener, more sustainable environment. Chicago has about 1,900 miles of public alleys, one of the largest alley networks of any city in the world. Many of the alleys are not connected to the city’s storm sewer system and are prone to flooding. The Green Alley program was created to improve stormwater drainage, reduce heat, and conserve energy in alleys.

Techniques include, but are not limited to: 

• Permeable pavements that allow storm water to filter though the pavement and drain into the ground.
• Drainage system to alleviate flooding. 
• Underground detention to store rainwater under the alley until the sewer system can handle the flow 
• High-albedo concrete for surface reflectivity to reduce heat island effect. 
• Recycled materials (concrete aggregate, slag, etc.)
• Proper grading and pitch to facilitate drainage.  

CDOT has installed more than 400 green alleys in Chicago since 2007 and has accelerated the pace of installation in recent years thanks to dedicated funding for the program in Chicago’s Capital Bond program. Each ward selects one green alley location per year to be constructed.

The handbook below provides an overview of CDOT's Green Alley program.

Green Alley Handbook (PDF)