A few feet

Because of President-elect Obama's plans to spend billions of dollars on infrastructure, some recent discussion of smart growth has focused on proposals for huge projects, such as rebuilding America's rail network.

But walkability often depends on much smaller steps, steps that require changes in tiny increments of space.

For example, take a typical tree-lined, upper-class suburban neighborhood, such as the fancier blocks of Atlanta's Buckhead.   A four-foot wide sidewalk, although not ideal, can make such a neighborhood very pleasant and walkable.  (For an example, see http://atlantaphotos.fotopic.net/p14704743.html )

Now substitute a strip of lawn for the sidewalk. (For examples, see http://atlantaphotos.fotopic.net/p44263562.html and http://atlantaphotos.fotopic.net/p14008023.html ) The neighborhood is not so inviting to pedestrians; although it is certainly possible to walk on this strip of lawn, the lawn can be muddy in rough weather, and a pedestrian might feel uncomfortable walking on something that is not obviously public space.  Nevertheless, a city that cannot afford to build new sidewalks would be well advised to encourage homeowners to allow a small easement on their lawn for pedestrians, since the lawn strip is better than the alternative, which is

Nothing.  In much of Atlanta, homeowners allow trees and bushes to go right up to the street, rather than flanking the street with lawns.  (For an example, see http://atlantaphotos.fotopic.net/p14010314.html ) As a result, pedestrians must walk on the street, sharing that street with vehicles. 

In sum, the fate of one or two strips of land just four feet wide makes the difference between a reasonably walkable residential street, a somewhat pedestrian-unfriendly street, and a street that virtually excludes pedestrians.

Even in the latter situation, a few feet makes a difference between the worst possible street and a merely bad one.  On many sidewalk-less residential streets, cars go 40 miles per hour, creating a very risky situation for pedestrians.  By contrast, when I visited my parents' vacation house in the mountains of North Carolina, people routinely hiked in the middle of the street.  Why?  Because the street was narrow enough that vehicle traffic was relatively slow, thus allowing pedestrians to reclaim the street to some extent.  Again, a few feet made a big difference.