Highways and Climate Change: Mitigation Strategies
Source: US EPA, Inventory of Greenhouse Gas Emissions and Sinks: 1990-2012, April 2014 (includes international bunker fuels).
Tailpipe greenhouse gas (GHG) emissions from transportation sources accounted for 29 percent of total U.S. GHG emissions in 2012, and over 4 percent of global GHG emissions. Including other life cycle processes-such as the extraction and refining of fuel, the manufacture of vehicles and the construction and maintenance of infrastructure-the U.S. transportation sector account for almost 6 percent of global GHGs. The majority of transportation's operating emissions, totaling 58 percent, come from light-duty vehicles, followed by freight trucks at 21 percent and aircraft at 11 percent. The Intergovernmental Panel on Climate Change (IPCC) estimates that without additional mitigation efforts beyond those in place today, and even with adaptation, warming by the end of the 21st century will lead to high to very high risk of severe, widespread, and irreversible impacts globally.
The strategies to reduce transportation GHG emissions are organized into four major groups. They include strategies to:
- Increase fuel efficiency by advancing and bringing to market advanced engine and transmission designs, lighter-weight materials, improved aerodynamics, and reduced rolling resistance. The objective of this group of strategies is to use less fuel and generate fewer GHG emissions.
- Introduce low-carbon fuels. Petroleum-based fuels account for 96 percent of U.S. transportation energy use. The objective of this group of strategies is to develop and introduce alternative fuels that have lower carbon content and generate fewer GHG emissions on a life cycle basis. These alternative fuels include ethanol, biodiesel, natural gas, liquefied petroleum gas, synthetic fuels, hydrogen, and electricity.
- Improve transportation system efficiency by optimizing the design, construction, operation, and use of transportation networks. The strategies range from anti-idling ordinances to traffic management to congestion pricing. The objective of this group of strategies is to reduce the energy use and GHG emissions associated with a given unit of passenger or freight travel (e.g., person-miles, vehicle-miles, or ton-miles of travel).
- Reduce travel activity by reducing growth in vehicle-miles traveled. The objective of this group of strategies is to influence travelers' activity patterns, thereby reducing total travel, shifting travel to more efficient modes, increasing vehicle occupancy, or otherwise taking actions that reduce energy use and GHG emissions associated with personal travel.
The largest reductions will result from changes in vehicle technology and fuels. However, growth in driving is projected to offset the GHG emissions savings from vehicle technology and fuel measures. Therefore, reductions are needed from all four of the strategies listed above. Transportation alternatives, paired with more efficient land use, are critical tools to reduce transportation-related GHG emissions.
FHWA Mitigation Resources
FHWA has developed several resources to help State DOTs and local agencies better analyze greenhouse gas emissions and energy use, evaluate GHG reduction strategies, and integrate climate change considerations into the transportation planning process.
- Greenhouse Gas/Energy Analysis Demonstration Projects- FHWA has recently initiat
ed partnerships with four transportation agencies to perform a planning level greenhouse
gas/energy analysis: Massachusetts DOT, Delaware Valley Regional Planning Council, East-
West Gateway Council of Governments, and the Southern California Association of Govern
ments. The effort was undertaken to encourage State DOTs and MPOs to incorporate green
house gas and energy considerations in the transportation planning process and to utilize
several new analysis tools and methods that FHWA has developed.
- Carbon Estimator (ICE) Tool- FHWA has developed a spreadsheet tool to help planners and NEPA analysts evaluate emissions from transportation infrastructure, including roads, bridges, transit facilities and bike / pedestrian infrastructure. The tool can also be used to help evaluate the emissions benefits of alternative construction and maintenance practices. The tool can be found at: http://www.fhwa.dot.gov/environment/climate_change/mitigation/publications_and_tools/carbon_estimator/
- Handbook for Estimating GHG Emissions in the Transportation Planning Process-The Handbook serve as a reference for State DOTs and MPOs by documenting available tools, methods, and data sources that can be used for development of GHG inventories, forecasts, and analyses of GHG plans and mitigation strategies. The Handbook can be found at: http://www.fhwa.dot.gov/environment/climate_change/mitigation/publications_and_tools/ghg_handbook/index.cfm
- GHG Policy Analysis Tool - The Energy and Emissions Reduction Policy Analysis Tool (EERPAT) was developed by FHWA for use by State DOTs to model a large number of inputs and policy scenarios to support strategic transportation and visioning including GHG emissions reduction alternatives. The tool can be used to assist State DOTs in analyzing GHG reduction scenarios and alternatives for use in the transportation planning process, climate action plans, scenario planning exercises, and meeting state GHG reduction targets and goals. The tool can be found at: http://www.planning.dot.gov/FHWA_tool/
- A Performance-Based Approach to Addressing Greenhouse Gas Emissions in Transportation Planning- This handbook was developed as a resource for State DOTs and MPOs interested in addressing GHG emissions through performance-based planning and programming (PBPP). It discusses techniques for integrating GHG emissions in PBPP, considerations for selecting relevant GHG performance measure(s), and ways of using GHG performance measures to support investment choices and enhance decision-making. The handbook can be found at: http://www.fhwa.dot.gov/environment/climate_change/mitigation/publications_and_tools/ghg_planning/index.cfm
- Transportation's Role in Reducing Greenhouse Gas Emissions (April 2010) - This report, mandated by the Energy Independence and Security Act of 2007, analyzes a full range of strategies available to reduce transportation's greenhouse gas emissions. The report was developed by the DOT Center for Climate Change and Environmental Forecasting, and can be found at: http://ntl.bts.gov/lib/32000/32700/32779/DOT_Climate_Change_Report_-_April_2010_-_Volume_1_and_2.pdf
- Pilot Testing of FHWA's Energy and Emissions Reduction Policy Analysis Tool (EERPAT) - FHWA is supporting the development and testing of its EERPAT tool with 4 Departments of Transportation. These pilots will help assess the sensitivity of EERPAT to mitigation strategies and identify future enhancements to the model. These projects are expected to be completed by early 2015.