The paper is an outline of empirical gaps on the subject of transportation and greenhouse gas (GHG) emissions, both mitigation and adaptation, which future research might be able to fill in. It's an important subject, since 28% of U.S. GHG emissions come from the transportation sector, and many types of transportation infrastructure are vulnerable to the effects of climate change. It's humbling to realize how much we have yet to learn on the subject. I've decided to quote the conclusion in its entirety:
"Public interest and policy attention on GHG emissions and climate change will likely become even greater in the coming years than they are today. Given that the transportation sector is a major contributor to GHG emissions and that much of our transportation system is vulnerable to changes in climate and local weather conditions, transportation officials will be heavily involved in the strategies for both mitigation and adaptation. Most national transportation officials and energy experts agree that the major source of GHG emissions reduction will come from vehicle and fuel technologies, that is, cleaner vehicles. However, attention will also be focused on transportation and land use strategies that will in the aggregate contribute to lower GHG emissions, or in the case of climate adaptation, deal with the effects of changing environmental conditions. A great deal is unknown about the role that transportation and land use actions can play as part of a comprehensive GHG strategy, and most importantly in reducing GHG emissions.
"I have identified several topics requiring research if transportation officials and planners are to have the tools and information they need to understand and manage many different aspects of climate change and GHG emissions reduction. I focused on the following particularly important research topics related to GHG mitigation: improved lifecycle analysis and cost effectiveness methods, incorporating other societal benefits and costs into evaluation, enhanced understanding of the relationship between land use and VMT and the corresponding implications for GHG emissions, and incorporating formal methods for handling risk and uncertainty into the analysis process. In addition, I emphasized the importance of learning from experience, both from prior policies and programs with similar characteristics here in the United States and from other countries.
"With respect to adaptation, I identified four major topics needing additional research: improved methods for identifying vulnerable transportation system assets, identification of appropriate strategies for dealing with a changing environment, methods for incorporating risk and uncertainty into analysis, and approaches to monitoring environmental conditions and feeding this information back into the decision making process.
"Finally, I also offered research topics related to specific questions that transportation planners will face as they consider GHG emission reduction strategies. Greenhouse gas emissions and climate change must be incorporated into the transportation planning process in different ways at each step in the process. Systems planning (including, among other things, visioning, choosing goals and objectives, data analysis, modeling, evaluation, and plan development), should consider GHG emissions in very different ways than project development. For example, project-level planning requires much more specific estimates of GHG emissions for each project option and mitigation strategies necessary for that particular location. Research should aim to answer the following important questions: What scale of GHG analysis is appropriate? What assumptions should be used in the GHG analysis? What methodologies, models, and data sources should be used? How should different GHG reduction strategies be evaluated? What variables have the greatest influence on GHG emissions, and what ranges of values should be tested? Should lifecycle GHG estimates be analyzed? How should GHG emissions be considered in prioritizing projects? How can transportation staff make the GHG analysis transparent to decision makers, other agencies, stakeholders, and the public? The answers to these questions could provide an important foundation for considering GHG emissions and climate change in the transportation decision making process."
Good work, you made it to the end :)