Quantifying GHG emissions is an important step in the process of integrating climate change into the transportation planning process. Transportation agencies, like State or local DOTs, Metropolitan Planning Organizations (MPOs) and transit agencies can estimate tailpipe GHG emissions in a variety of ways, from using fuel and vehicle travel data, to using travel models and scenario planning techniques. Transportation agencies also need to determine the scope of their inventory and measurement work, specifically whether they want to be inclusive of emissions from materials, fuels, construction, and maintenance.

When establishing measures and targets, a common first step is to develop a baseline. Many states have developed a GHG inventory, which may include total GHG emissions attributed to activities in the state, not just transportation. Transportation agencies can take different approaches to developing performance measures and setting reduction targets. The NCHRP report Assessing Mechanisms for Integrating Transportation-Related Greenhouse Gas Reduction Objectives into Transportation Decision Making describes two types of reduction targets—total quantity and per capita—and addresses different baseline types. More information on tools and methodologies can be found on the USDOT GHG Analysis Resources and Tools website.


Step one of the transportation planning process- goals, objectives, performance measures, and targets- is an important step to integrate GHG considerations into. (Credit: FHWA)


The Oregon DOT has multiple performance measures focused on reducing GHG emissions that are highlighted in an appendix of the Oregon Transportation Plan. Many of these measures are pulled from Oregon DOT’s Statewide Transportation Strategy and include GHG emissions for ground passenger and commercial services, emissions for freight, measures for improving the energy efficiency of Oregon’s vehicle fleet, and more. Oregon developed key performance targets for three main lenses the agency wants decisions to be made through – safety, equity, and climate. The climate targets include reducing passenger vehicle miles travelled per capita by 20 percent and transitioning to cleaner vehicles and fuels to reduce carbon dioxide equivalent per mile by 77 percent.

In June 2022, the National Capital Region Transportation Board (TPB), the MPO for the Washington D.C. area, established targets to reduce on-road GHG emissions by 50 percent from 2005 levels by 2030. These targets were integrated into the Visualize 2045 long-range transportation plan. TPB is among the first MPOs to voluntarily adopt transportation specific GHG emissions reduction targets.

To learn more about Integrating GHG Assessment and Reduction Targets in Transportation Planning, contact David D’Onofrio, FHWA Office of Natural Environment, or Jim Thorne, FHWA Office of Planning, or subscribe to the team’s e-newsletter.

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