Environmental Justice Implications of Roadway Topography

Project ID: CTEDD 019-09

Author(s): Franklin Gbologah, Georgia Institute of Technology

Co-Author(s): Michael Rogers, Georgia Institute of Technology

CTEDD Funding Year: 2019 General RFP

Project Status: Complete

UTC Funding: $61,297

End Date: August 31, 2020


Automobile emissions from highways are known to have harmful effects on the public. These harmful effects also raise concerns of environmental justice because their severity is highest near the transportation network. Established methodologies used in regional planning to identify the critical extent of emission dispersal from the highway and also to demarcate the boundaries of population group that is most at risk uses a fixed distance buffer analysis. These established methodologies also do not account for the effect of roadway topography on amount of emissions.

However, recent studies have shown that roadway topography can result in overestimation or underestimation of the quantity of emissions. The spatial concentration of pollutants depends to a large extent on quantity emitted. Therefore, it is possible, depending on local conditions, that a fixed distance buffer analysis could overestimate or underestimate the boundaries of the affected population.

This proposed research will investigate the implications of roadway topography on the ubiquitous fixed distance of 200 m that is usually used in analysis. It will use Vissim simulation to generate grade modified vehicle activity data over high traffic highway corridor and use the vehicle activity data to estimate emission inventories. The estimated emissions will be used as input in an air dispersal model to investigate the spatial concentration of the pollutant from the highway in order to verify the adequacy or inadequacy of the fixed critical distance.

The findings from this research will be beneficial to decision makers at Metropolitan Planning Organizations (MPOs) and city governments who have to consider environmental justice effects of their transportation plans. This research is significant because it will increase our understanding on whether existing methodologies are doing enough to accurately account for populations that are exposed to the detrimental effects of automobile emissions.