The Professional Geographer (2002) 54(2): 226-240.
Bringing Time Back In:
A Study on the Influence of Travel Time Variations
and Facility Opening Hours on Individual Accessibility
Joseph Weber and Mei-Po Kwan
Abstract: Although recent studies of individual accessibility
have used detailed representations of urban street networks, unrealistic
measures of travel time based on assumptions about constant travel speeds
through the network were often used. Utilizing constant travel times does not
allow for daily congestion and assumes that the effects of congestion are
uniform throughout the city and affect all people equally. This research
measures individual space-time accessibility in order to show that the
incorporation of locally specific travel times within a street network allows a
significant increase in the ability to realistically evaluate individual
accessibility within cities. The results show that the accessibility of
individuals within cities is not homogenous, and neither does access to
employment or shopping opportunities vary according to common expectations about
urban form and human behavior. Instead, the role of distance in predicting
accessibility variations within cities is quite limited. This article also shows
that incorporating time into accessibility measures in the form of congestion
and business hours leads to additional (and highly spatially uneven) reductions
in accessibility, revealing that the temporal dimension is very important to
accurately assessing individual accessibility.
Key Words: accessibility, geographic information systems, time.
View Full Paper .
Return to Kwan's Homepage