There is general scientific consensus that the earth is experiencing a long-term warming trend and that human-induced increases in atmospheric greenhouse gases (GHGs) are the predominant cause. The combustion of fossil fuels is by far the biggest source of GHG emissions. In the United States, transportation is the largest source of GHG emissions, after electricity generation. Within the transportation sector, cars and trucks account for a majority of emissions.
Opportunities to reduce GHG emissions from transportation include switching to alternative fuels, using more fuel efficient vehicles, and reducing the total number of miles driven. Each of these options requires a mixture of public and private sector involvement. Transportation planning activities, which influence how transportation systems are built and operated, can contribute to these strategies.
In addition to contributing to climate change, transportation will likely also be affected by climate change. Transportation infrastructure is vulnerable to predicted changes in sea levels and increases in severe weather and extreme high temperatures. Long-term transportation planning will need to respond to these threats.
The objective of this study is to advance the practice and application of transportation planning among state, regional, and local transportation planning agencies to successfully meet growing concerns about the relationship between transportation and climate change. This report explores the possibilities for integrating climate change considerations into long range transportation planning at state DOTs and MPOs. The report reviews the experience of a number of DOTs and MPOs that are already incorporating climate change into their transportation planning processes and identifies their successes as well as challenges faced by these agencies.
Our research for this report was conducted in four stages. First, we reviewed typical long-range transportation planning practices. We examined the inputs and outputs of each major step in transportation planning for relevance to climate change planning. We consider broadly how transportation planning could be enhanced to take account of GHG emissions and the risk posed to transportation systems by climate change.
Second, we reviewed federal regulations and statutes that govern transportation planning. While current regulations do not mention climate change or GHG emissions, parts of regulations can be interpreted as relevant to climate change. We point out these interpretations and general opportunities to link federal regulation of transportation planning to climate change.
Third, we reviewed a sample of current planning documents from state DOTs and MPOs for incorporation of climate change. We initially reviewed documents from 12 DOTs and 18 MPOs nationwide. We included a mix of small and large organizations from all regions of the country. We analyzed both long-range transportation plans (LRTPs) and related documents for integration of climate change.
Finally, we conducted interviews with four DOTs and eight MPOs that are working to incorporate climate change into long range transportation planning. We probed for successes, barriers and solutions, and common approaches. We identified trends across agencies' experiences with planning for climate change.
Note that opinions stated in this memo represent the viewpoints of individual staff members at DOTs and MPOs and are not necessarily official agency positions.
The remainder of this report presents our research findings. Section 2 contains our review of planning practices and federal regulations. Section 3 presents a summary of current practices among state DOTs and MPOs. Section 4 discusses the integration of climate change into the text of LRTPs. Each of Sections 5-8 focuses on a specific trend or topic area in planning for climate change. We describe current practices, barriers, and needs, and provide supporting examples from specific DOTs and MPOs. Section 9 discusses issues for future research.