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Transportation accessibility


“The proper metrics will ensure that transportation agencies are doing the right thing, not just doing the thing right”


scores for various neighborhoods can then be compared, as can, for example, accessibility by transit versus accessibility by automobile. An average can be calculated for a metropoli- tan region by calculating the average, weighting the acces- sibility for each neighborhood (or traffic analysis zone, or other small area) by the population in that neighborhood. The trend can then be tracked over time. Comparing different regions is more difficult, because the


number of jobs varies from region to region. One approach that focuses on transportation may be to normalize the metric for each region by calculating the percentage, rather than the absolute number, of jobs in the region that the average resident can reach within 30 minutes.


North America Vol 8 No 3


BARRIERS TO IMPLEMENTATION There is a growing awareness of the limitations of mobility metrics alone, and of accessibility as a concept, however this has yet to translate into widespread practice. If accessibility is such a useful concept, why isn’t it more widely used? There are two reasons. First, until recently, it was very difficult to collect the necessary data and conduct the analyses. Data was rarely readily available in an appropriate electronic format, and proprietary Geographic Information Systems (GIS) or transportation planning toolsets were required. Second, the metric crosses the divide between the planning and opera- tions communities. The rapid growth in open data (eg, for transit schedule


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