The City is flatter: Changing patterns of job and labor access

• Using Cumulative Opportunities Accessibility, we find the region is flatter, or more converged in 2005 than 1995.
• Suburban areas increased most rapidly in accessibility to jobs.
• Network changes are more localized, and land use changes have more regional effects.
• The center of access of the region has moved westward over this period.
• Overall the region has higher accessibility, despite higher congestion.

This study measures accessibility by automobile for the Minneapolis - Saint Paul (Twin Cities) region from 1995 to 2005. In contrast to most 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 transport 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 transport network structure and land use (opportunity location) reveals 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 transport system.