Uncovering JAPA

Assessing Who, Where, and Why Individuals Walk

In recent years, urban planners, policymakers, and the general public have become interested in walking especially in light of the ongoing pandemic and its spatial consequences. Walkability-based concepts and interventions, such as the 15– or 20–minute city, are increasingly attractive. However, the empirical foundations of such ideas, specifically the drivers, constraints, and actual lengths of walk trips, remain underexplored.

Walkability Study Assesses Trip Distances Empirically

In "Redrawing the Planners' Circle: Analyzing Trip-Level Walk Distances Across Two National Surveys" (Journal of the American Planning Association, Vol. 87, No. 4), authors Louis A. Merlin, Denis Teoman, Marco Viola, Hailey Vaughn, and Ralph Buehler attempt to fill this gap by assessing patterns of walk trips across the United States and Germany. They investigate whether the so-called planners' circle or walkshed of one-quarter mile — frequently drawn on maps to indicate walk distances — should expand or contract.

Prior research has identified several determinants of walking behavior found in the body of published literature — from issues of density and perceived comfort to demographic and attitudinal factors. Merlin et al. built on this work using the national household travel surveys (often shortened to NHTSs) from the U.S. and Germany to tease out variables that influence walk-trip distance.

Walk Lengths Vary Based on Culture

Given the large datasets, all variables were found to be statistically significant, but two showed the largest differentiations across categories: age of walker and trip purpose. Interestingly, the youngest cohort in the U.S. walks the most distance, while their German counterpart walks the least. Purpose of trip was also found to be an important predictor of trip length: work and school commutes are similar across the countries (about 0.60 and 0.52 miles, respectively in both), but leisure and errand trips are substantially longer in Germany. Based on this, the authors theorize that cultural factors, as opposed to the physical ability of the walker, are the predominant influencers of walking behavior.

The authors conclude with a plea for planners to consider the diversity of walkers, walk lengths, and walk purposes, and to plan for longer — if less frequent walk trips. (The 90th percentile of leisure trips in the U.S., for example, approaches one mile in length.) I thought an even more compelling conclusion was the authors' admission that different cultural, aesthetic, and historical conditions among the countries can explain the divergent walking behaviors, though those factors are difficult to measure and control for in studies. It might be interesting to find ways to measure those intangible but highly influential aspects of cities. Indeed, having spent a lot of time over the years in a handful of German cities, it's clear an attractive, eclectic, and exciting streetscape is an important factor in getting people to walk, and to walk further distances. Or, to continue with the authors' metaphor, it can be a key source of expanding the planners' circle.

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About the author
Akiva Blander is a Master of Urban Planning candidate at Harvard University.

November 18, 2021

By Akiva Blander