Rethinking Prism Anchors: Investigating Space-Time Fixity and Flexibility of Activities using Smartphone-Based Activity-Travel Survey Data

Authors: Yaxuan Zhang*, University of Minnesota, Ying Song, University of Minnesota, Yingling Fan, University of Minnesota
Topics: Spatial Analysis & Modeling, Temporal GIS, Geographic Information Science and Systems
Keywords: Time Geography, Space-Time Anchor, Human Activity Dynamics, Trajectory Analysis
Session Type: Virtual Paper
Day: 4/10/2021
Start / End Time: 1:30 PM / 2:45 PM
Room: Virtual 9
Presentation File: No File Uploaded

The space-time prism is a fundamental concept in time geography that delineates all accessible locations given individuals' scheduling constraints. Following the concept, at-home, work, and school activities are often considered as prism anchors that are usually fixed in both space and time. Other activities such as shopping and recreation are relatively flexible and therefore scheduled between fixed activities. But this fixed-flexible dichotomy ignores that different social-economic and demographic status of individuals may lead to distinct views on how flexible an activity is in their daily schedules. This paper investigates the space-time fixity and flexibility of various types of activities from a data-driven perspective. For spatial fixity, we first examine the stationarity of an activity type, and then the location variations of stationary activities and the route variations of non-stationary activities. For temporal fixity, we examine whether the time allocation for an activity type is fragmented or condensed within one day. For space-time fixity, we focus on stationary activities that have no significant variations in space and time, which can be used to define anchors of prisms. To illustrate our methods, we use multi-day activity-travel survey data collected by a smartphone application, Daynamica, from residents in the Twin Cities metropolitan area in 2016-2017. The results suggest that at-home, work, and school activities are not often fixed in space or time, while other activities may have more fixed schedules.

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