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Suggested Citation:"Chapter 1 Summary." National Academies of Sciences, Engineering, and Medicine. 2022. Methods for State DOTs to Reduce Greenhouse Gas Emissions from the Transportation Sector. Washington, DC: The National Academies Press. doi: 10.17226/26523.
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Page 1
Page 2
Suggested Citation:"Chapter 1 Summary." National Academies of Sciences, Engineering, and Medicine. 2022. Methods for State DOTs to Reduce Greenhouse Gas Emissions from the Transportation Sector. Washington, DC: The National Academies Press. doi: 10.17226/26523.
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Page 2
Page 3
Suggested Citation:"Chapter 1 Summary." National Academies of Sciences, Engineering, and Medicine. 2022. Methods for State DOTs to Reduce Greenhouse Gas Emissions from the Transportation Sector. Washington, DC: The National Academies Press. doi: 10.17226/26523.
×
Page 3
Page 4
Suggested Citation:"Chapter 1 Summary." National Academies of Sciences, Engineering, and Medicine. 2022. Methods for State DOTs to Reduce Greenhouse Gas Emissions from the Transportation Sector. Washington, DC: The National Academies Press. doi: 10.17226/26523.
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Page 4

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1 C H A P T E R 1 Summary Purpose of Project The objectives of the National Cooperative Highway Research Program (NCHRP) Project 25-56 were to develop a guide to assist State departments of transportation (DOT) in evaluating ways to reduce transportation greenhouse gas (GHG) emissions through their activities and decision-making, and to pilot test and improve this guide by working with a select number of DOTs and their local partners. The guide is published as NCHRP WebResource 1: Reducing Greenhouse Gas Emissions: A Guide for State DOTs. The guide aids DOTs by breaking down technical and institutional issues related to GHG estimation and reduction across the spectrum of an agency’s activities. The guide can be used by individual functional areas in contributing to an integrated agency effort. Each of the guide’s functional unit sections enables individuals to directly access the information they need in order to understand and affect GHG reduction strategies. The guide was not intended to duplicate existing materials on transportation GHG strategies and evaluation methods, but rather to cross-reference in-depth sources that already are available. Project Approach The project was scoped with eight tasks divided into three phases. At the conclusion of the first and second phase, an interim report was delivered to the Project Panel proposing a detailed timeline and workplan for the next phase. The first phase of work, which took place between the summer of 2018 and the winter of 2019, included a review of practice; an assessment of needs, opportunities, and barriers; and development of an annotated guide outline and Phase 2 outreach plan. Research methods included a survey of State DOTs, interviews with selected DOT staff, and a review of State DOT documents related to GHG emissions estimation and reduction. The second phase of work, which took place between the winter and summer of 2019, included the development of six initial sections of the draft guide; workshops with three State DOTs and partner agencies; an online briefing for a national State DOT audience; and development of a detailed Phase 3 workplan. The third phase of work, which took place between the fall of 2019 and the winter of 2021, included development of the full guide; virtual workshops and other technical assistance with four State DOTs and partners to test and implement the draft guide; and finalization of the guide and project report. Key Findings Regarding State DOTs and GHG Reduction A “level of engagement” framework was used to characterize DOT activities related to GHG reduction, ranging from Level 1 (“just getting started”) to Level 4 (a comprehensive approach). As categorized based on survey responses, most State DOTs are at relatively early stages of addressing GHG emissions— “Level 1” or “Level 2” engagement. A few have been more active, categorized as “Level 3” or “Level 4,” and that number has been increasing as more State executives and legislative bodies set aggressive goals to address climate change and reduce emissions. Even the “Level 4” agencies, however, acknowledge that they still have much work to do in fully integrating GHG considerations into their activities, and taking many of the steps that would be needed to support more aggressive GHG reduction targets.

2 A common question from the workshops is, “what is the most effective thing we can do as an agency to reduce GHG emissions?” But a concurrent theme is, “how much will it cost, and how will it impact our other operations and priorities?” There is no silver bullet for a DOT. DOTs can lead by example, such as by electrifying their fleets and procuring low-carbon materials. These emissions sources, while under the direct control of the DOT, are relatively small compared to emissions from transportation system users. The project team developed estimates of transportation-related emissions for a “typical” State, based on composite data from multiple States. These estimates show that the great majority of emissions (about 94 percent) are from the operation of vehicles using the highway system. Emissions associated with construction, maintenance, and operations of the State’s highway system are about 6 percent of the total, and emissions from the DOT’s administration (buildings and light-duty fleets) are about 0.2 percent. The relative scale of these sources is illustrated in Figure 2.9 of the guide. Transportation system user emissions are influenced by the DOT less directly through policy, planning, and operational decisions. Effective implementation of most of these strategies requires collaboration with other agencies and stakeholders, and the DOT may not always be the lead agency, especially for solutions such as clean vehicle technology. Sample findings from GHG scenario analyses conducted by various agencies, as presented in Section 3.0 of the guide, provide some lessons learned about which strategies are likely to be most effective. First, a widespread transition to clean energy sources, most likely through electrification, will be needed to achieve the aggressive GHG targets being set by governments at all levels to mitigate the most severe effects of climate change. Mobility-focused solutions, such as travel demand management and traffic flow improvement, will be an important, but limited, part of an overall set of GHG reduction measures. Pricing strategies can be one of the most effective ways of managing mobility, but can be challenging to implement. Some choices that a DOT makes will align well with other imperatives, such as improving travel time and safety, reducing criteria air pollutant emissions, working towards energy independence, or achieving cost savings through fuel savings. Others may require difficult tradeoffs. For example, investing in new highway capacity may reduce emissions in the short term, but may be counterproductive in the long term if it leads to induced demand and increases automobile use. These are conversations to be had with stakeholders and the public. Table 1-1 summarizes observations from past and ongoing State efforts to reduce GHG emissions and implications for State DOTs, as referenced in Section 3.0 of the guide. Table 1-1. GHG reduction strategies: observations and implications for DOTs. Observation State DOT Implications Most emission reductions will come from clean vehicle and fuel technologies. Support electric and alternative fuel vehicle infrastructure for light and heavy vehicles, clean transit, and clean fleets. Demand reduction and systems efficiency strategies can reduce emissions by up to 5 to 20 percent. Implement intelligent transportation systems (ITS)/efficient traffic operations. Invest in and support low-carbon travel alternatives and incentives to manage demand for vehicle travel. DOT construction materials, fuels/fleets, and buildings provide an additional reduction potential of 2 to 3 percent of total transportation system emissions. Use low-carbon, recycled/reused materials, where feasible. Switch to clean fuel light and heavy vehicles. GHG reduction targets of 75 to 80 percent or more by 2050 are challenging and will require widespread electrification and a clean grid. Collaborate with other State, regional, and local agencies.

3 Observation State DOT Implications Most strategies require implementation at multiple levels (State, regional, and local). State DOTs have many moving parts that must be coordinated to address GHGs. First and foremost, strong direction from leadership is required for a concerted and sustained effort. Furthermore, if anything is going to be done to address any overarching issue within a DOT context, some organizational unit with motivated staff must lead and still others must deliver in cooperation with other parts of the agency. Complex operations like GHG reduction require many organizational units to operate in a concerted manner, and each must be trained, equipped, and directed to play its role within the constraints of competing priorities and available resources. Initial steps can include the development of an “executive charter” to establish objectives and use of a cross-agency working group that meets on a regular basis to report on progress and ensure accountability. The guide includes “self-assessment” tools that can help an agency plan out action items and assign responsibilities. Significant GHG reductions will be the product of years of work involving a wide range of agency functions, which also will tend to evolve over time. Ideally, most GHG reduction efforts can be at least reasonably aligned with the department’s principal mission as the program matures. Key Findings Regarding Conduct of Similar NCHRP Research and Implementation Projects From a procedural standpoint, there were three noteworthy aspects of this project. The first was the extensive amount of outreach and engagement that took place as part of the development of the guide. Rather than waiting for a final product to engage the intended audience, NCHRP has been moving towards engagement as part of the development process. Experience in this project suggests that this is a successful means of building interest in the product, conveying technical information to the intended audience, and gaining feedback to shape the product to be as useful as possible. Three rounds of outreach were conducted: the first to establish a baseline of existing practices; the second to test preliminary material, including a subset of the guide; and the third to refine a draft version of the complete guide. Seven State DOTs hosted workshops, with two additional DOTs and numerous partner agencies participating. While the project team offered additional technical assistance to apply tools and methods presented in the guide, DOTs engaged mainly through the workshops for reasons discussed in this report. The second was the evolution of the guide to focus less on technical resources (data and computational tools) and more on institutional procedures and practices. It became clear in the initial outreach that the existing resources describing available technical tools were reasonably good, but that resources did not exist to direct a State DOT on how to integrate GHG considerations across its spectrum of activities. Technical tools for estimating GHG emissions and evaluating mitigation strategies are still in need of development, but those needs are not the focus of this NCHRP project. The final guide contains significant technical resources, but is primarily focused on procedures and relationships; most notably, it includes a series of custom “self-assessment” tools designed for each functional area of the DOT. The third noteworthy aspect was the development of the final guide in webresource format. While this publication format already has been used by the Airport Cooperative Research Program, it is the first application for an NCHRP project. This format allows for a more interactive engagement with the user, making it easier to navigate between sections and to link to material of interest. Development in this format required some additional resources on the part of the project team, compared to producing only a traditional printed or PDF document, but feedback from the workshops suggests that it improves the user experience.

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Many technical and institutional issues related to estimating and reducing greenhouse gas emissions (GHGs) lie across a wide spectrum of the activities undertaken by state departments of transportation (DOTs).

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 308: Methods for State DOTs to Reduce Greenhouse Gas Emissions from the Transportation Sector documents the research effort for an NCHRP project that focused on developing a guide for state DOTs on reducing GHG emissions. The result of this effort, NCHRP WebResource 1:Reducing Greenhouse Gas Emissions: A Guide for State DOTs, presents tools, methods, and data sources for state DOTs to use in reducing GHG emissions from the transportation sector.

Supplemental to the Web-Only Document is a presentation summarizing the research.

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