Sidewalks play a vital role in city life. As conduits for pedestrian movement and access, they enhance connectivity and promote walking. As public spaces, sidewalks serve as the front steps to the city, activating streets socially and economically. Safe, accessible, and well-maintained sidewalks are a fundamental and necessary investment for cities, and have been found to enhance general public health and maximize social capital.
Just as roadway expansions and improvements have historically enhanced travel for motorists, superior sidewalk design can encourage walking by making it more attractive.
The sidewalk is the area where people interface with one another and with businesses most directly in an urban environment.
Façades and storefronts should be designed to cater to the eye level of pedestrians.
See Interim Design Strategies
Street trees enhance city streets both functionally and aesthetically. Trees provide shade to homes, businesses, and pedestrians. Street trees also have the potential to slow traffic speeds, especially when placed on a curb extension in line with on-street parking, and may increase pavement life by avoiding extreme heat. Aesthetically, street trees frame the street and the sidewalk as discrete public realms, enriching each with a sense of rhythm and human scale.
Requirements for tree spacing depend upon a number of key factors and should be tailored to the chosen species, standard (or desired) tree pit size, fixed property lines, setback from curb, and integration with street lights and other furniture.
Street trees may be removed to satisfy sight distance or clear zone requirements only in extreme cases, where the installation of traffic control devices has been precluded. Larger trees protect pedestrians from errant vehicles.
The concept of “clear zones” is sometimes cited in the highway design process. A clear zone represents an unobstructed, traversable area beyond the traveled way, often a paved or planted shoulder or a short setback on the sidewalk.9 Clear zones provide a run-off zone for errant vehicles that have deviated from the main roadway and are intended to decrease the frequency and severity of fixed-object roadside crashes, forgiving driver error.10
See Design Speed
While clear zones are applicable as a safety parameter for the Interstate and freeway system, in urban settings, delineation of a minimum set back from the curb is not a required element. To the greatest extent possible, the lateral distance between the traveled way and the sidewalk (or parking lane) should be minimized, providing ample space for sidewalks and other amenities.11
Removal of roadside impediments (trees, street furniture, etc.) has an ambiguous safety record in urban environments and is at odds with city policies striving to increase pedestrian traffic and spur economic activity. Street trees and other roadside features are superior to wide shoulders or run-off zones, as they can decrease overall speeds and encourage a more pedestrian-friendly environment.
Bill Ryan, “Let’s Talk Business: Ideas for Expanding Retails and Services in Your Community,” UW Extension, July 2003.
Shannon H. Rogers, John M. Halstead, Kevin M. Gardner, and Cynthia H. Carlson, “Examining Walkability and Social Capital as Indicators of Quality of Life at the Municipal and Neighborhood Scales,” Applied Research Quality of Life 6 (2010): 201–213.
Design and Engineering Manual (Washington, D.C.: D.C. Department of Transportation, 2009): 29–3.
Americans With Disabilities Act of 1990.
A Policy on Geometric Design of Highways and Streets, 4th Edition (Washington, D.C.: AASHTO, 2001).
Roadside Design Guide, 4th Edition (Washington, D.C.: AASHTO, 2011).
Adapted from the Urban Street Design Guide, published by Island Press.