The impacts of accessibility measure choice on public transit project evaluation: A comparative study of cumulative, gravity-based, and hybrid approaches

Document Type

Journal Article

Publication Date

2023

Subject Area

mode - bus rapid transit, place - north america, place - urban, technology - geographic information systems, planning - methods

Keywords

Bus rapid transit, Transit system redesign, Transit project appraisal, Spatial accessibility, GIS

Abstract

This paper investigates whether different types of accessibility measures can perform similarly when evaluating changes in accessibility before and after transport interventions. Specifically, we compare three types of placed-based accessibility approaches: 1) cumulative-opportunity, 2) gravity-based, and 3) hybrid of the two. We conduct a comprehensive comparison of 12 accessibility measures by combining different operational forms, impedance functions, and parameters to see if the results of project appraisals are sensitive to the choice of accessibility measure. For case studies, we consider two scenarios in Canada: new bus rapid transit (BRT) services in Vancouver and transit system redesign (TSR) in Edmonton. We carry out high spatio-temporal resolution accessibility analyses based on General Transit Feed Specification (GTFS) datasets through an open-source transit analytics tool. Results demonstrate that the three types of measures perform differently when evaluating changes in accessibility pre and post transit interventions. Accessibility change scores generated by cumulative-opportunity measures are notably different from those produced by gravity-based and hybrid measures. Also, the capability of cumulative-opportunity approach in capturing the geographic extent of areas affected by transit interventions is limited. We found that the project appraisal results can even change from positive to negative or vice versa, depending on the chosen accessibility measure. We recommend an analyst test several types of accessibility measure with a range of parameters for a more robust evaluation on the impacts of new public transit services on accessibility. We share our code and data to promote reproducible transportation science in planning practice.

Rights

Permission to publish the abstract has been given by Elsevier, copyright remains with them.

Comments

Journal of Transport Geography home Page:

http://www.sciencedirect.com/science/journal/09666923

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