Transportation Strategies to Cut Carbon Emissions

Despite prospects for more efficient vehicles and lower-carbon fuels, total carbon emissions from the transportation sector are projected to remain relatively unchanged unless rising trends in overall travel demand and improvements in system efficiency are addressed. Climate legislation that establishes a market price for carbon emissions is estimated to have a lesser effect on transportation emissions, indicating the importance for additional, complementary measures to achieve overall emission reduction goals and avoid shifting emission reduction costs to other sectors.

This briefing focused on Moving Cooler, a recent report sponsored by a consortium of federal agencies, transportation organizations, and environmental groups that examines the potential effectiveness, benefits, and costs of a wide range of transportation policy options. These options include measures to manage travel demand, such as pricing mechanisms that are more proportional to the amount of travel and compact development strategies that reduce distances between travel destinations; measures to shift to more carbon-efficient travel modes (public transportation, ride-sharing, biking, and walking, and more efficient freight movement); and measures to make system operations more efficient, including intelligent transportation systems (ITS) that improve management of traffic flow, optimized travel speed, enhanced vehicle operation, and capacity expansion to relieve traffic bottlenecks.

On October 21, the Environmental and Energy Study Institute (EESI) held a briefing on strategies to reduce oil consumption and carbon dioxide emissions from the surface transportation sector. Energy and climate legislation pending before the Congress contains measures to enhance the efficiency of the overall transportation system as well as measures to promote more efficient vehicles and fuels. Implementation of these measures, however, will face technical, logistic, and institutional challenges. The briefing addressed these challenges and explored ways that they can be overcome.

• The transportation sector accounts for 28 percent of U.S. greenhouse gas (GHG) emissions and 70 percent of U.S. oil consumption. Therefore, it is critical to achieving national goals for GHG reductions and energy independence.
• Under current trends and policies, GHG emissions from transportation are projected to remain constant or decline only slightly. Increases in miles traveled by light-duty and heavy-duty vehicles are projected to negate most gains from increased vehicle efficiency and reduced carbon fuels.
• Transportation strategies to reduce GHG emissions have upfront and continuing costs, but these costs decline over time. Savings, however, increase over time and far outweigh initial costs in the long run.
• Aggressive deployment of a combination of strategies to manage transportation demand and increase efficiency of transportation supply can reduce GHG emissions up to 35 percent from projected baseline. No single strategy, with the exception of nation-wide pricing measures, was shown to reduce greenhouse gas emissions more than a few percent; some individual strategies yield less than a half percent reduction in emissions.
• State, metropolitan, and local transportation agencies need appropriate federal incentives, policies, and resources to implement GHG reduction strategies. The Corporate Average Fuel Economy (CAFE) standards of 35.5 miles per gallon by 2016 are a step in the right direction, but there are limitations. For example, CAFE does not address heavy-duty vehicles, which are responsible for approximately 20 percent of GHG emissions from the transportation sector.
• CLEAN-TEA (S. 575 / H.R.1329), federal legislation introduced by Senator Tom Carper, Senator Arlen Specter, Rep. Earl Blumenauer and other House members, is an important policy measure to reduce transportation emissions by managing transportation demand and efficiency. Major provisions of CLEAN-TEA have been incorporated into the climate legislation (S. 1733) recently introduced by Senators John Kerry and Barbara Boxer.
• State transportation departments need to coordinate with Metropolitan Planning Organizations as well as integrate their GHG reduction goals with other priorities such as safety and access.
• The U.S. Department of Transportation (DOT) has several initiatives to support and complement state and metropolitan efforts to reduce GHGs from transportation. Grant programs within the U.S. DOT and within the climate legislation proposed in Congress provide competitive funding sources for transportation projects, and these programs could serve as models for future legislation.