Reducing Transport Sector GHG Emissions in a Medium-Sized US City


Research the leading methods for quantifying urban transportation-related greenhouse gas (GHG) emissions, as well as the processes for moving from GHG inventories to the design and implementation of sustainable transportation plans. For a selected medium-size US city, design and draft a comprehensive sustainable transportation plan.


On a US national level, greenhouse gas (GHG) emissions from the transportation sector contribute about one third of total emissions. In a large city such as New York, buildings contribute 75%, and the transportation sector about 20%. What about the many fast-growing US cities in the 60,000 to 200,000 population range? One might hypothesize that their transport sectors contribute a relatively larger share of GHG emissions, given that mass transit is often less developed than in major urban centers. Undoubtedly, for any medium-size US city embarking on a sustainability plan that measures GHG emissions, transportation-related emissions must be a central concern. That said, quantifying transportation-related emissions on any scale is a challenging endeavor.  By its nature, transportation involves passage of vehicles—autos, trucks, buses, trains, and airplanes—across city boundaries and indeed across state and sometimes national boundaries. Which emissions should be counted, and how? What emissions allocation methods are called for in a given urban context?  Different conceptual models have been proposed, e.g., transboundary infrastructure supply chain (TBIS) footprinting, and consumption-based footprinting. In creating a transportation-related GHG inventory for a city, a number of quantification methodologies need to be considered.[1] An optimal methodology (or customized variant) must be selected and consistently executed, if a city’s sustainable transportation planning is to have real and lasting GHG emissions-reduction results. This project will explore these issues, analyze options, and develop a recommended course of action for a selected medium-size US city.

Suggested Approaches

(i)  Conduct an initial literature review with the goal of becoming familiar with the leading conceptual models and quantification methodologies relevant to creating an urban transportation-related GHG inventory.

(ii)  Select and investigate as case studies the transportation planning of some medium-size US cities (e.g., Boulder, CO; Portland, OR; etc.) that appear to be leaders in sustainable transportation planning. Analyze the models and methodologies they use in developing transportation-related GHG inventories. Then review and analyze the essential follow-through processes by which these cities move from GHG inventories to the design and implementation of sustainable transportation plans.

(iii)  Select a medium-size US city for detailed transportation-planning analysis. Based on the prior research (into GHG inventory models/methodologies and design and implementation strategies), design and draft a comprehensive sustainable transportation plan for that city. The plan should consider projected urban growth, financial costs, and environmental impacts in the process of deriving plausible transportation-related GHG emission reduction scenarios.

[1]  See, e.g., a paper of the World Resources Institute, “Citywide Transportation Greenhouse Gas Emissions Inventories: A Review of Selected Methodologies,”….