Green Alley

The majority of residential alleys have low traffic and infrequent repaving cycles, resulting in back roads with potholes and puddling that are uninviting or unattractive. Green alleys use sustainable materials, pervious pavements, and effective drainage to create an inviting public space for people to walk, play, and interact.¹

Recommendations

1Construct green alleys with low-impact pavement materials, such as pervious pavements with high reflectivity to reduce heat island effects.

2Alleys may be operated as pedestrian-only environments or as shared streets. Use bollards, signs, and design features that make clear the intended alley users.

Alley greening and maintenance may be initiated and carried out by local residents or neighborhood associations.²

3To avoid puddling, stormwater run-off should be infiltrated in-place using permeable paving or rain gardens at the edge of the pedestrian path.³

4To maintain a safe environment, green alleys should have adequate lighting. Pedestrian scale light fixtures that focus their illumination toward the ground and minimize light pollution are recommended. Public safety is of paramount consideration for all new and existing alleys. Good lighting is an essential prerequisite to a feeling of public safety in alleys.

5Green alleys often run parallel to the larger street network, making them ideal low-speed, low-volume links for cyclists.

Alleys provide direct property access and eliminate the need for driveways along main roads where people are walking and biking. Consider the use of alleys in all new developments and renovations to existing properties.⁴

Green alleys may present certain unconventional maintenance responsibilities. Use of textured pavements and other materials may be challenging to existing street sweepers and snowplows. Similar to shared streets, alleys may benefit from the application of snowplow compatible materials and provisions for maintenance equipment access.

DETROIT, MI
This alley in Detroit was transformed to manage stormwater using pervious pavement and native plants along the walkway.

1. Chicago’s Green Alley Handbook provides guidance on alleyway design and suggestions for green alley adjacent properties.
   The Chicago Green Alley Handbook, (Chicago: Chicago Department of Transportation, 2010).
   
   Seattle’s Integrated Alley Handbook estimates that the city contains 217,500 square feet of alleys, of which 85% are underused. This handbook provides excellent alley prototypes based on a variety of land uses. For more information, see:
   Mary Fialko and Jennifer Hampton, Seattle Integrated Alley Handbook: Activating Alleys for a Lively City, (Seattle: University of Washington, 2011). ↩︎
2. The City of Baltimore’s Alley Gating and Greening Program enables neighbors adjacent to an alleyway to decide if they would like to partially or fully close the alleyway for greening projects.
   “Alley Gating & Greening Program,” City of Baltimore, accessed May 31, 2013, http://www.baltimorecity.gov/Government/AgenciesDepartments/GeneralServices/AlleyGatingGreeningProgram.aspx. ↩︎
3. The U.S. Environmental Protection Agency provides a wealth of literature related to green infrastructure, including bioswales, rain gardens, and other techniques for reducing the impact of large quantities of water during storms. For more information see the EPA’s website on Green Infrastructure.
   “What is Green Infrastructure?,” U.S. Environmental Protection Agency, accessed May 31, 2013, http://water.epa.gov/infrastructure/greeninfrastructure/index.cfm.
   
   The City of Seattle’s Street Edge Alternative Program’s primary objective is to restore natural drainage patterns to manage stormwater and prevent flooding. The program achieves these objectives through the reduction of impervious surfaces and increases in planting and other natural elements. “Street Edge Alternatives,” City of Seattle, accessed May 31, 2013, http://www.seattle.gov/util/environmentconservation/projects/drainagesystem/greenstormwaterinfrastructure/completedgsiprojects/streetedgealternatives/. ↩︎
4. Street and Site Plan Design Standards, (Chicago: Department of Transportation, 2007), 23. ↩︎

Urban Street Stormwater Guide

Learn more about stormwater in NACTO’s Urban Street Stormwater Guide

Read the Guide