Choice set formation with multiple flexible activities under space-time constraints

Xiang Chen, Mei Po Kwan

Research output: Contribution to journalArticlepeer-review


In classical time geography, an individual travel path is composed of a chain of visits, with each visit being a flexible activity between two fixed activities at two known stations. In reality, individuals tend to carry out trips with much variation and complexity, with multipurpose trips being a prominent and pervasive phenomenon. There is limited research to date on multipurpose trips in time-geographic analysis by geographic information system (GIS) scientists, or more specifically, multiple flexible activities between two fixed stations. To fill this gap, this article proposes four models for identifying the choice set with multiple flexible activities under space-time constraints. The models are derived through set-theoretic formalism based on the concept of trip chaining. The structure of the four models establishes a theoretical framework for conceptualizing trip-chaining behaviour with respect to the fixity of activities and the number of fixed stations as destinations or origins. They provide fundamental and rigorous apparatus for studying complex individual activity-travel patterns in many applied contexts when multipurpose trips are involved. This article also describes implementation of the models with a real transportation network as a way of validation.

Original languageEnglish (US)
Pages (from-to)941-961
Number of pages21
JournalInternational Journal of Geographical Information Science
Issue number5
StatePublished - May 2012
Externally publishedYes


  • choice set
  • multiple flexible activities
  • multipurpose trips
  • space-time constraints
  • trip chaining

ASJC Scopus subject areas

  • Information Systems
  • Geography, Planning and Development
  • Library and Information Sciences


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