Getting Charlie Off the M.T.A.: A Method for Including Cost Constraints in Public Transit Accessibility Metrics

Accessibility metrics are used in public transport planning more and more frequently. An often-used accessibility metric is the cumulative opportunities metric, which sums opportunities available within a particular travel time cutoff. However, for low-income travelers, some of these opportunities may not be available because the transit fare exceeds their ability to pay (particularly with higher-cost services, such as commuter rail). In this article, the authors introduce a method to add a monetary cutoff to the cumulative opportunities metric, producing counts of opportunities accessible/subject to a maximum travel time and a maximum travel cost simultaneously. The key challenge with including fares in accessibility metrics (or any shortest-path algorithm) is that fares exhibit path dependence; the fare to ride a transit vehicle often depends on what fares have been paid previously (due to free or discounted transfers). The authors' method solves this challenge by also keeping track of the maximum potential discount at future transfer points within the shortest-path algorithm. This implementation allows an efficient multicriteria search, returning a Pareto set of travel time and monetary cost given a general transit fare system. Retaining the lowest-fare path even when a faster path exists confers an advantage over previous research that first finds the shortest path and then assigns a fare. Transfer incentives are included, an advantage over methods that assign a single generalized cost to each transit link. The algorithm is demonstrated using a case study in greater Boston, Massachusetts, USA.

  • Supplemental Notes:
    • This paper was sponsored by TRB committee AP030 Standing Committee on Public Transportation Marketing and Fare Policy.
  • Corporate Authors:

    Transportation Research Board

  • Authors:
    • Conway, Matthew Wigginton
    • Stewart, Anson F
  • Conference:
  • Date: 2019


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Maps; References;
  • Pagination: 5p

Subject/Index Terms

Filing Info

  • Accession Number: 01698003
  • Record Type: Publication
  • Report/Paper Numbers: 19-05048
  • Files: TRIS, TRB, ATRI
  • Created Date: Dec 7 2018 9:43AM