Ten features of walkable communities

The following features of walkable communities were presented this week by Wade Walker, a transportation engineer with Kittelson & Associates. This is a great list, although not definitive; other lists of 10 could be made. Here's Walker’s list, with my comments.

1. Small block size. The average block size in a walkable place should be no more than six acres, preferably 2-3 acres, or even smaller. Portland, Oregon, is famously walkable, with blocks downtown only about an acre in size. Small blocks provide so much interest and variety—the corners are where the action is. This feature may be counter-intuitive because smaller blocks mean more streets to cross. In theory, that might impede walking with small blocks, but it doesn't. A lifetime of walking cities and towns assures me that the smaller the block, the more walkable the place. I can’t argue with walker placing this feature number one on the list.
2. Buildings fronting the street. This is Urbanism 101. Streets are humanized by buildings that form active, urban frontages such as storefronts, porches, and stoops. In walkable communities, buildings form the walls of outdoor rooms, and the frontages support human activities. 
3. Mixed land use. Communities without mixed use are boring to walk, and the destinations are too far away and often separated by barriers from living spaces. Walkable communities are, by definition, mixed-use; if there is nothing to walk to, the place cannot be walkable.
4. Connected streets. In the 1960s, Christopher Alexander wrote A City is Not a Tree. The famous essay made the case for connected street networks, as opposed to cul-de-sacs branching off of arterial roads of suburbia. A connected street network is a close cousin of small block size. The first thing I look for in walkable places is the (sometimes modified) street grid.
5. On-street parking. This feature may be controversial because it includes cars. And yet, most great streets have on-street parking, which slows traffic and provides a barrier between moving vehicles and pedestrians on the sidewalk. On-street parking is also the most efficient way to share parking 24/7, and is vastly superior to parking lots from the walkability standpoint.
6. Street trees. Street trees make everything better. They provide shade and cooling, beauty, pollution mitigation, store rainwater, calm traffic, and more. 
7. Sidewalks. This one is obvious. Separate the pedestrians from the motor vehicles. 
8. Narrow streets. New urbanists have pushed for narrow streets to create walkable places for 30 years, a plea often ignored by traffic engineers. Research has recently been published from Johns Hopkins University that supports the safety of narrow travel lanes, attracting attention to this issue. Narrow streets are almost synonymous with walkability.
9. Lower traffic speeds. There is no more reliable way to make a street more walkable than to lower traffic speeds. This is the most important element of any complete street project.
10. Traffic volumes. In a landmark study from 1981, Donald Appleyard determined that those who live on low-volume streets had three times more friends (in the neighborhood) than those living on heavily trafficked streets.

Walker presented this list in an On the Park Bench presentation on Planning for Physical Activity. He pointed out that most features are associated with urban design and planning—and only traffic speeds and volumes (the final two on the list) are the exclusive province of transportation engineers. But if you want to create a walkable place or improve walkability anywhere, boosting these characteristics will probably help.