Many state departments of transportation (DOTs) are engaged in efforts to reduce their operational greenhouse gas(GHG) emissions. While most state DOTs have a long history of taking actions to conserve resources and improvethe efficiency of their operations, usually to achieve cost savings, most have not conducted a full accounting of theseactions and do not have a good understanding of the GHG emissions benefits of their various initiatives.This paper describes an approach to evaluating the effectiveness of the California Department of Transportation’s efforts to reduce GHG emissions. The study involved collecting data on each strategy and applying GHG emissions and cost factors to estimate the total GHG reductions and cost-effectiveness of different strategies. This analysis serves as a basis for early action by identifying the most effective GHG reduction strategies and opportunities to further reduce emissions, and reveals several findings that can help guide GHG reduction efforts among DOTs across the U.S. First, there is substantial potential to reduce GHG emissions by using more sustainable materials in construction and maintenance of the transportation system, but it can be challenging for DOTs to increase the use of these materials while minimizing costs and maximizing quality. Second, the use of energy-efficient lighting in the roadway system is the most cost-effective for DOTs to achieve substantial GHG reductions. Third, the GHG reductions from using alternative fuels in DOT fleets vary widely for different fuels, so in order to maximize reductions DOTs must focus on increasing the use of fuels with the lowest carbon content. Finally, many of the things that DOTs already do to save money, minimize the need for maintenance, and conserve resources also reduce GHG emissions, and these strategies can anchor more comprehensive GHG reduction efforts.
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