Walking to Public Transport: Rethinking Catchment Areas Considering Topography and Surrogate Buffers

Service, or catchment areas of public transport stops are traditionally assessed using Euclidean or network distances, often neglecting other relevant factors such as topography. This study proposes a refined approach that integrates network-based accessibility with terrain variations and the effect they have on walking time and on the physical effort required for pedestrian movement. Using geographic information systems-based analysis that include walking time and walking energy cost models, the impact of topography on accessibility to public transport is evaluated in a case study of the hilly city of Coimbra, Portugal. Results show that, as compared to their flat counterparts, network distance-based service areas that consider hilliness, exhibit a decrease in accessibility of circa 10% in terms of area covered and population affected. These findings highlight the need for more realistic accessibility assessments to support more realistic and equitable public transport planning. Because extensive network datasets are not always available to decision-makers, this article also introduces the concept of surrogate buffers as a practical alternative for obtaining catchment areas, summarized by the “0.7/0.6R rule”.