TRB Special Report 307: Policy Options for Reducing Energy Use and Greenhouse Gas Emissions from U.S. Transportation examines the potential for policies to yield major changes in transportation energy use and emissions trends by policy measures targeting cars and light trucks, medium and heavy trucks, and commercial airliners. These three modes are by far the largest users of energy by U.S. transportation because they account for the vast majority of passenger trips and freight.

According to the committee that produced the report, it will take more than tougher fuel economy standards for U.S. transportation to significantly cut national petroleum use over the next half century. It will likely require a combination of measures that foster consumer and supplier interest in vehicle fuel economy, alternative fuels, and a more efficient transportation system.

Major policy options examined in the report-fuel taxes, vehicle efficiency standards, fuel standards, infrastructure investments, and coordinated transportation and land use planning-have the potential to bring about large energy and emissions savings from these modes over time; however, each option presents particular challenges with respect to the scope and timing of its impacts. The report suggests that combining transportation policy options to increase the timeliness and expand the scale and scope of the response may be warranted.

Saving energy in transportation can have important implications for the cost of securing the world's oil supplies, since transportation accounts for most of the petroleum consumed in the United States. It can also help with controlling the buildup of greenhouse gases (GHGs), which will require major reductions in carbon dioxide (CO2) emissions from economic sectors that are heavy users of carbon-rich fossil fuels. Scientific analyses and models indicate a need to stabilize atmospheric concentrations of CO2 and other GHGs by the middle of this century to reduce the risks of climate change. A response by the transportation sector to this energy and emissions challenge will be important because it produces between one-quarter and one-third of all of the CO2 emitted from the country's energy consumption.