Where people walk: Two new studies improve “walkability” measurement

By Chris McCahill
In planning and designing for pedestrians, sidewalks are often a good start but rarely make a place walkable on their own. Measuring pedestrian accessibility (the topic of a recent SSTI webinar) depends on two important pieces of information: 1) where destinations are located, and 2) the quality of the walking network connecting to those places. This second point is the focus of two studies published in a recent issue of the Transportation Research Record: Journal of the Transportation Research Board.
Walk Score is a useful metric for beginning to understand if places are walkable based on the variety of nearby destinations and certain characteristics of the built environment. However, it only partially explains people’s tendency to walk, according to one new study in Montreal. This is because WalkScore doesn’t capture some important factors affecting people’s walking experience, such as surface parking and street trees.
In the Montreal study, researchers gathered information about the prevalence of parking lots and building setbacks from digital land use data and information about tree canopies from GIS data maintained by the city. Controlling for factors like automobile-orientation and demographics, they found that these additional characteristics significantly improve their ability to predict walking. Walking is less likely in places with more parking and larger setbacks, and more likely when there is good tree coverage.
Extending this concept further, researchers in Singapore developed a Pedestrian Accessibility Tool that accounts for how features and conditions like roadway characteristics, greenery, building frontage, crossings, and weather affect people’s perceived travel time while walking. These estimates are based on hundreds of carefully designed visual preference surveys administered online. Figure 1 shows the perceived difference between two similar roadways based on factors such as active building frontage, pedestrian cover, and greenery. Without those features, a person’s perceived travel time is more than twice as long, meaning they’re also less likely to walk along that route.

Figure 1. Differences in perceived travel time based on visual preference surveys in Singapore. Source: Erath et al., 2015.

Understanding these factors will be even more important as transportation agencies incorporate pedestrian accessibility metrics into decision making, as Virginia has done with its Smart Scale project prioritization process.
Chris McCahill is an Associate Researcher at SSTI.