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VIEW POINT Transportation accessibility


“As long as traffic moves freely, it doesn’t matter, according to these measures, how long the total trip time is, or, in fact, whether or not the trip is even necessary”


information and street maps), improved traffic speed and travel time data for arterials and other streets, and new free tools, such as OpenTripPlanner Analyst, have greatly reduced the technical barriers. For example, the Brookings Institu- tion made extensive use of transit schedule data available in the standard General Transit Feed Specification (GTFS) for- mat for their comprehensive study of transit-based access to jobs in 100 cities across America. The open source OpenTripPlanner project, originally


developed to provide transit agencies with a tool trip plan- ning tool for riders, has added OpenTripPlanner Analyst to support, among other things, accessibility analysis. What remains are the institutional divides. “There is an institutional divide between transportation


planning and management and land planning and man- agement. Mobility measures still dominate discussions of system performance in transportation. Also transportation agencies feel they do not control land use, so that including it in the performance measures is not helpful, while land plan- ning agencies feel they do not control transportation,” states Professor David Levinson, RP Braun CTS Chair in Trans- portation at the University of Minnesota. However, even within the planning community, there is a large variance in the extent to which agencies are utilizing


Who has the Better Commute?


According to the study Driven Apart, drivers in Charlotte, North Carolina encounter an average delay of 9.6 minutes and have a Travel Time Index of 1.25, while Chicago drivers encounter an average delay of 9.8 minutes and have a Travel Time Index of 1.43. Based on these conventional congestion metrics, Charlotte commuters are better off. But this is just part of the picture. Chicago commuters tend to live closer to their jobs, and their average commute times are just 32.6minutes, whereas the average Charlotte worker spends 48 minutes traveling to his or her job. Most commuters would gladly choose a slightly more congested trip if, in fact, that trip took 30 per cent less time.


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Performance metrics should capture all possible solutions


accessibility metrics in their activities. Some planning agen- cies have adopted these metrics. Montgomery County, Mar- yland, for example, includes “Mean Travel Time to Work” as a metric. The Sacramento Area Regional Council of Govern- ments has long included accessibility as an explicit metric in their planning activities. At the same time, other planning agencies fail to make a clear distinction between mobility and accessibility. “There is still more talk about accessibility as a goal than


actual measures of accessibility, as there is still no standard practice on this,” reports Dr Susan Handy, the Director of the Sustainable Transportation Center at the University of California Davis.


A VISION FOR THE FUTURE Performance-based management should be built around outcomes, and accessibility is one of the best available met- rics for assessing how well a region’s transportation networks provide the desired outcomes. Increases in the availabil- ity of data in usable, electronic form, combined with more powerful and less expensive processing tools have signifi- cantly lowered the barriers to routine use of accessibility as a performance metric, offering hope that accessibility may become a more widely used. This shift could be accelerated by AASHTO and/or the USDOT recognizing accessibility as a key performance metric under MAP-21 and related efforts. As Professor Levinson and his colleague, Emilia Istrate have written, “A recommended federal measure would provide a benchmark for the state and local agencies, which then could develop their own accessibility metrics.”


thinkinghighways.com Vol 8 No 3 North America


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