Everyday Cycling in Urban Environments: Understanding Behaviors and Constraints in Space-Time - Computational Approaches for Urban Environments - page 187

be relevant to the investigation. Sampling cyclists for a particular cycling research
project is a challenging task for researchers (Krizek et al. 2009 ). The sampling
criteria for the study are articulated as follows: any adult utility cyclist who is more
than 19 years and willing to freely volunteer as a participant; should be a utility
cyclist and commute by bicycle at least once a day in a week; must have home,
work, or school location within Newcastle upon Tyne geographic area; and must be
willing to carry a personal GPS device continuously for 1 week. A week is defined
as 7 days of the week which is from Monday to Sunday.

8.4.1.3 Space-Time Cube-Based Data Processing

Space-time cube (STC)-based processing is the idea of exploiting and using the
STC space construct, as originally proposed by Hägerstrand ( 1970 ) and adopted by
Kapler and Wright ( 2004 ), to edit raw GPS data by mainly visual inspection with
additional data (Yeboah 2014 ; Yeboah and Alvanides 2013 ; Yeboah et al. 2012 ). By
using the STC in this way, the applicability and usability of the cube achieve a com-
plete cycling of data cleaning, analysis, and visualization (Fig. 8.3 ). The raw GPS
data - after some basic checks on time zone, column headers, and coordinate system
using the QTravel Software which comes with the GPS device - is imported into an
STC using GeoTime software ( www.geotime.com ) and its link into the ArcMap
environment. The basic check is also to ensure that the raw GPS data is properly
downloaded with correct time zone settings. In the process of export/transfer, the
attributes of the data are mapped to enable GeoTime to load all attributes of
the raw data to enable further selection and visual inspection in STC space in
GeoTime. Additional secondary information, such as OpenStreetMap ( http://wiki.
openstreetmap.org ) basemap, is loaded in ArcMap, and this reflects automatically in
the GeoTime STC space. It is at this point that travel diaries are consulted to identify
cycle trips in a particular date and time. The identified information is visually

Fig. 8.3 Space-time cube
usability cycle ( Source:
adapted from Yeboah ( 2014 ))