The Half-Mile Circle: Does It Best Represent Transit Station Catchments?

One-half mile has become the accepted distance for gauging a transit station’s catchment area in the U.S. It is the de facto standard for planning TODs (transit oriented developments) in America. Planners and researchers use transit catchment areas not only to make predictions about transit ridership and the land use and socioeconomic impacts of transit, but also to prescribe regulations, such as the relaxation of restrictive zoning, or carve out TOD financial plans. This radius is loosely based on the distance that people are willing to walk to transit, but this same reasoning has been used to justify other transit catchment areas. Using station-level variables from 1,449 high-capacity American transit stations in 21 cities, we aim to identify whether there is clear benchmark between distance and ridership that provides a norm for station-area planning and prediction. For the purposes of predicting station-level transit ridership, we find that different catchment areas have little influence on a model’s predictive power. This suggests that transit agencies should use the easiest and most readily available data when estimating direct demand models. For prescribing land-use policy, by contrast, the evidence is less clear. Nevertheless, we find some support for using a quarter-mile catchment area for jobs around transit and a half-mile catchment for population. While these distances will likely vary from place to place and depending on the study purpose, they are a good starting point for considering transit-oriented policy or collecting labor-intensive data, such as surveys, about transit-adjacent firms or households.