Street Design

 

The United States is experiencing a paradigm shift in neighborhood design. Individuals and groups are developing innovative strategies by which to make new or existing neighborhoods  more walkable, enjoyable and livable. After years of neglect, street design is regaining its status as a vital element of neighborhood and town planning.

The reasons for this status are self-evident: people want to live on streets where there are low traffic volumes, slow speeds and minimal noise. Residents also seek proximity to parks, schools and other facilities for their children, while many baby boomers’ changing mobility means new desire for sidewalks, trails, greenways and open space. However, the streets and neighborhoods built since the 1950s have often created the opposite conditions: wide streets full of fast, noisy traffic and subdivisions that encourage automobile dependence. The walk to the corner store for a pound of bread has, for many, been replaced with a drive in a 2 ton vehicle. Even when stores lie close to homes, land uses are separated to such an extent that it’s often impossible to reach them without a motor vehicle.

This separation of uses is common in modern zoning codes. The typical layout of a conventional community (as shown on the right side of the diagram below) locates residential, commercial and civic buildings in distinct enclaves that are often connected only through larger arterial roadways As a result, the child living in the residential subdivision to the bottom right of the diagram cannot visit the local park unless she is driven there. The same is true of most other trips an individual or family wants to make. Therefore, most trips require use of a car, thereby exacerbating already congested arterial roadways.

Traditional vs Conventional Development Diagram

In contrast, the traditional neighborhood seen on the left side of the diagram places houses, schools, shops and offices in close proximity to each other. Its street design provides a fully connected travel network with multiple routes to destinations. A child can comfortably walk or ride a bike to the park without confronting any 8- or 10-lane arterial roadways .

The contrast between these two models extends even further. Because streets in the conventional neighborhood are longer and serve more people than those in the traditional neighborhood, they tend to be wider and thus to allow higher traffic speeds. The emphasis on motor vehicle capacity has encouraged traffic engineers to design streets with minimal obstacles for errant drivers, so trees are often set at a distance from the roadway and on-street parking is discouraged. The resulting wide streets and long blocks, then, literally encourage speeding and discourage walking and biking. A 1998 study of 20,000 accidents over a 20-year period by Swift & Associates of Longmont, Colorado found a direct correlation between street width and accident rates. The safest streets were roughly 24 feet wide. As streets gained width the number of accidents (per mile, per year) increased. Therefore, higher traffic speeds that often result from wider streets may account for this rise in traffic accidents.

The traditional neighborhood street, however, is narrow and lined with trees that not only help calm traffic but also increase comfort for walkers and cyclists. Many residents and local officials are recognizing that these traditional streets help form more livable neighborhoods. As a result, efforts are underway to design or retrofit more streets to mirror these characteristics, including such measures as ‘traffic calming.’ The latter denotes a set of mostly physical treatments to roadways that help manage traffic flow and encourage safer, more civil driver behavior within districts and neighborhoods. Traffic speed, noise and volume are often reduced, and traffic distribution rebalanced, via such measures. The LGC has published a detailed guide to traffic calming that explains the technical and collaborative processes required for its implementation.

Meanwhile, the New Urbanist movement, advocating neotraditional neighborhood design that incorporates features of older, mixed-use, traditional communities, continues to grow. The LGC’s Street Design Guidelines for Healthy Neighborhoods discusses in detail many of the design principles and techniques involved in this type of planning.

Resources

The Local Government Commission has developed several guidebooks that discuss how to design or retrofit streets and neighborhoods to make them more supportive of walking and bicycling.

Our series of 4-page illustrated fact sheets with a Focus on Livable Communities provide a brief, easy-to-read overview on the following key topics related to walkable communities:

Single copies of these fact sheets are available free from the LGC and can also be downloaded in PDF format from our web page. Bulk copies for wider distribution are also available at a nominal fee.

An additional fact sheet, The “Transportation Tools to Improve Children’s Health and Mobility”, highlights engineering solutions for more walkable communities.

Web Links

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