The City is Flatter

Recent working paper:

This study describes the measurement of accessibility by automobile for the Minneapolis – Saint Paul (Twin Cities) region over the period from 1995 to 2005. In contrast to previous analyses of accessibility, this study uses travel time estimates derived, to the extent possible, from actual
observations of network performance by time of day. A set of cumulative opportunity measures are computed with
transportation analysis zones (TAZs) as the unit of analysis for 1995 and 2005. Analysis of the
changes in accessibility by location over the period of study reveals that, for the majority of locations in the
region, accessibility increased over this period, though the increases were not uniform. A “flattening” or
convergence of levels of accessibility across locations was observed over time, with faster-growing suburban
locations gaining the most in terms of employment accessibility. An effort to decompose the causes of changes in
accessibility into components related to transportation network structure and land use (opportunity location) reveal
that both causes make a contribution to increasing accessibility, though the effects of changes to the transportation
network tend to be more location-specific. Overall, the results of the study demonstrate the feasibility and
relevance of using accessibility as a key performance measure to describe the regional transportation system.