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Green Accessibility

Accounting for Environmental Costs in Sustainable Transportation Planning
October 9, 2015

Recent advances in modern technologies such as mobile phones and Global Positioning Systems (GPS) make it possible to track movements in geographic space over time. The ever-increasing availability of the movement data marks the “Era of Big Data” and unprecedented interest in visualizing, analyzing, and utilizing these spatio-temporal datasets to support sustainable transportation planning. 

Time geography, a theory developed by the Swedish geographer Torsten Hägerstrand in 1970, has been widely applied to measure individuals’ space-time accessibility in an environment and opportunities within that environment. It can be used to represent individuals’ movements over space and time as they participate in different activities such as working and shopping during certain hours. Given the vast amount of empirical movement data now available, there are many possible ways to study where and when people move in their daily activities. However, most studies have focused on the mobility-related benefits, such as participating in social activities and accessing health services, but ignore the potential costs of such movements, such as fuel consumption, greenhouse gas emissions, traffic fatalities, and exposure to pollutants. 

Dr. Ying Song has developed an approach that can estimate the mobility-related costs of individuals’ movements over space and time. This research is part of a larger project entitled “Green Accessibility: Measuring the Environmental Costs of Space-time Prisms in Sustainable Transportation Planning” that is funded by National Science Foundation (NSF) and involves collaboration among geographers, civil engineers, and planners. This research can help us to understand individuals’ driving behaviors given their activity schedules, and the potential environment costs associated with them. The computational and analytical methods of her approach can be applied to other types of movements (e.g., animal movements) as well as various mobility-related costs. Dr. Song, a new Assistant Professor in the Department of Geography, Environment, & Society, is excited to explore further collaboration with other research centers (such as the Center for Transportation Studies and the Minnesota Population Center), as well as professionals at other institutions, agencies, and organizations in the Twin Cities in order to apply her research to the local area.