U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590

Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration

Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

Public Roads
This magazine is an archived publication and may contain dated technical, contact, and link information.
Public Roads Home | Current Issue | Past Issues | Subscriptions | Article Reprints | Author's Instructions and Article Submissions | Search Public Roads
Publication Number:      Date:  March/April 1998
Issue No: Vol. 61 No. 5
Date: March/April 1998


Sustainable Transportation: The Road From Kyoto

by Kevin Heanue and Susan B. Petty

"A sustainable condition for this planet is one

in which there is stability for both social and physical systems,

achieved through meeting the needs of the present without

compromising the ability of future generations to meet their own needs."

-United Nations World Commission on Environment and Development

(Brundtland Commission, 1987)

At the Kyoto Conference in December 1997, the world's nations struggled to set binding limits on greenhouse gas emissions to protect future generations. Because climate change is a global and long-term issue, the urgency of this effort is easily denied. The evening news does not show flooding of parts of the coastal United States, widespread drought, or lost food production. However, the consequences of global climate change are serious enough to bring 159 nations together in Kyoto, Japan, to work toward a global agreement on an issue, the impact of which may be years away. This worldwide focus on a future issue is very unusual.

Global emissions chart. For the transportation community, the Kyoto Conference creates the opportunity -and the demand -to begin research and initiatives to work toward a sustainable transportation system. A sustainable transportation system will meet today's needs for access and economic growth without compromising the ability of future generations to meet their own needs. Motor vehicles emit 25 percent of the U.S. carbon dioxide (CO2) emissions. If worldwide transportation trends continue, along with energy use in other sectors, emissions will continue to increase and contribute to global climate change. This is not sustainable; changing the average temperatures and rainfall patterns around the world will create an irreversible impact on future generations.

Transportation is only one component of global climate change. Even if all transportation systems were sustainable, global warming would continue. However, transportation systems are not sustainable today, and the transportation community must do its part along with other consumers of fossil fuel if a solution is to be found.

Sustainability is a broader issue than global climate change. A transportation system cannot be sustainable and only address an environmental issue. A sustainable transportation system balances short- and long-term needs for the environment, economic growth, and community. To meet the global warming challenges of Kyoto and the broader issue of sustainable transportation, we must consider how transportation decisions that we make today may create long-term economic, environmental, and community changes.

This article has three purposes. One is to provide an overview of the global climate-change issue and transportation's role in it. The second is to describe the broader problem of sustainability. The third purpose is to begin to define the issues and challenges to the transportation community so that "the road from Kyoto" is an opportunity to create a sustainable transportation system for the future.

What Are the Options?

Global climate change is a central issue in sustainability and will lead much of the discussions. However, as previously mentioned, a sustainable transportation system requires more than simply addressing CO2; it must balance short- and long-term needs for the environment, economic growth, and equity -the "three E's" of sustainability. The strategies of the transportation community to address global climate change must be developed in the context of sustainability.

Projected petroleum use and emissions chart. A number of studies and commissions have focused a worldwide, public policy debate on the basic tenants of sustainability. An important, recent publication is the Transportation Research Board's (TRB) Special Report 251: Toward a Sustainable Future. The TRB report is the work of 18 experts in environmental sciences, economics, transportation, and public policy. It is an excellent primer, providing background on the science and policy options to address three sustainability issues: global climate change, biodiversity, and habitat.

The United States contributes a disproportionate share of greenhouse gases and motor vehicle emissions. Carbon dioxide accounts for 85 percent of the U.S. greenhouse gas emissions. We have only 4 percent of the world's population, but we produce more than 23 percent of the global emissions of CO2 produced from fossil fuel. Our per capita emissions of CO2 are about 50 percent greater than the average for the other countries in the Organisation for Economic Co-operation and Development (OECD).

Figure 1 shows the dramatic increases in global energy-related emissions from carbon since 1900. The CO2 emissions in 1995 in the United States came from three main sources: industrial production (34 percent); heating, cooling, and electrical power for buildings (35 percent); and transportation (31 percent). The transportation percentage included motor vehicle travel, production of fuels, manufacturing of vehicles, and construction of transportation facilities. Clearly, transportation is a significant part of the problem.

Emissions from motor vehicles in the United States account for most of the transportation-related greenhouse gas emissions. On average, the current car fleet in the United States gets 16.9 miles per gallon (7.1 kilometers per liter). Each gallon (3.8 liters) produces 19.5 pounds (8.85 kilograms) of CO2 or 1.15 pounds of CO2 per mile (0.33 kilograms per kilometer).

In 1995, the U.S. motor vehicle fleets used 143 billion gallons (541 billion liters) of motor fuel, creating 2,800 billion pounds (1,270 kilograms) of CO2 . All motor vehicles in the United States accounted for about 25 percent of the U.S. CO2 emissions -about 5 percent to 6 percent of the worldwide CO2 emissions.

Note that this is not carbon monoxide (CO), which is one of the toxic pollutants that cause smog and affect the quality of the air we breathe. Carbon dioxide (CO2) from natural sources is an essential part of the upper atmosphere. The global climate-change problem comes from the man-made production of CO2.

The TRB report also found that transportation infrastructure, developmental patterns, and agricultural practices such as the use of fertilizers and insecticides are having long-term impacts on biodiversity and habitat. Less is known about these small, incremental, and accumulating effects that may be producing irreversible changes in the ecosystem over the long term. For example, the effects of nitrous oxides in the atmosphere cause the slow accumulation of acid in soils, and this changes land and water ecosystems. This affects forest growth and causes regional changes in the variety of plants and trees. Habitats have been altered through the developmental patterns and transportation infrastructure that created barriers dividing habitats. While we do not anticipate building significant new miles of highways, the report recommends that we increase our knowledge of habitat fragmentation caused by existing transportation systems and that we pursue opportunities to ameliorate the effects of the fragmentation.

TRB explored a number of options for reducing CO2 over the next 40 years. These options included reducing travel demand through transit and land-use strategies, deploying new technologies, and increasing the price of energy to influence both travel choices and the demand for new technology. (See table 1.)

Projected carbon dioxide emission chart. The proposals at Kyoto call for the United States to reduce total greenhouse gas emissions 7 percent below the 1990 levels. The options evaluated by TRB would individually only slow the growth of motor vehicle emissions of CO2, but in combination, these strategies could reduce the total. While transportation accounts for one-third of the total CO2 emissions, significant short-term reductions of CO2 emissions from transportation sources will be difficult to achieve.

TRB reviewed current projections and demographic trends to develop a baseline scenario for growth in motor vehicle travel over the next 40 years (see figure 2) to compare the impacts of various transportation strategies. In the baseline scenario, TRB estimates motor vehicle travel will increase 1.5 percent a year and will thus double by the middle of the next century. Under this baseline scenario, the amount of CO2 emitted by U.S. vehicles will increase at about the same rate. TRB notes that such long-term projections are not probable, but the projections are useful benchmarks to compare other scenarios and options.

Over time, travel-related trends have changed. The Corporate Average Fuel Economy (CAFE) program combined with higher prices for gasoline and disruptions in foreign oil supplies during the mid-1970s caused the average fuel economy of the car fleet to improve by one-third from 1980 to 1990. However, without revisions to the CAFE standards and with the public's lack of interest in more fuel-efficient vehicles, the average fuel efficiency of the fleet has not improved much since the late 1980s. About half of the new vehicles purchased this year are sport-utility vehicles and light trucks, which are heavier and less fuel-efficient than cars.

Table 1 summarizes the options analyzed by TRB and shows that it will take 20 to 40 years to begin to see significant reductions in the growth of emission levels. Several automakers have announced that they plan to market cars with very high fuel efficiency and/or very low emissions.

Figure 3 shows the implications of greater use of low-emission vehicles or increased fuel economy. The rate that the older, high-emission vehicle fleet is replaced would be dependent on public acceptance and demand and possibly on incentives and fees. But over 20 years, each measure -taken alone -would only reduce the growth in CO2 emissions by a small amount. Waiting for technology to provide a solution is not going to be enough.

What Do We Know About Climate Change?

The scientific debate is no longer about whether greenhouse gases are accumulating or if global climate change is going to occur. The issues are now whenthe change will be noticed and how it will affect every aspect of our environment. The excess greenhouse gases that cause global climate change -primarily carbon dioxide, nitrous oxide, and methane -are in the stratosphere. Different pollutants -carbon monoxide, ground-level ozone, and particulate matter -are causing the air-quality problems in our cities. The climate-change problem is caused by human activities (anthropogenic) that are forcing natural systems out of balance. The effects of greenhouse gases are worldwide, causing climate changes that have been decades in the making and will take decades to slow and return to balance.

Human activities account for only about 5 percent of the greenhouse gases, but the increase is more than the oceans, forests, and soils can absorb. This may seem like a very small percentage, but it is enough to have dramatic effects. It's similar to filling your coffee cup 5 percent over the rim!

The most important source of anthropogenic CO2 is the burning of fossil fuels -coal, petroleum, and natural gas. The generation of electricity, manufacturing, transportation, and energy used in buildings have all increased the amount of greenhouse gases in the atmosphere. This situation has been exacerbated by the clearing of forest lands, particularly in tropical regions, which play a large part in cleaning CO2 from the atmosphere.

Another important factor is the longevity of greenhouse gases in the outer atmosphere. CO2 has an atmospheric lifetime of 50 to 200 years, depending on the rates of uptake by the different sink processes. In contrast, the pollutants that cause smog in urban areas last only days or weeks in the lower levels of the atmosphere.

The increases in CO2 account for about half of the global warming. Increases in other greenhouse gases, such as nitrous oxides, methane, hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs), also contribute to serious, long-term problems. Much has been learned about the effect of acid rain on forests and plants, but more must be learned about the very long-term effects of greenhouse gases.

What Were the Results From Kyoto?

The Kyoto Conference in December was the fourth worldwide meeting on climate change. Earlier meetings in Rio de Janeiro, Berlin, and Geneva produced a nonbinding framework and goal to reduce emissions of greenhouse gases to 1990 levels by the year 2000. However, this goal was not met by the developed countries, including the United States, and it was hoped that the Kyoto Conference would produce binding agreements.

While binding agreements were not finalized, the industrialized countries agreed to proposed targets. The United States proposed to reduce greenhouse gas emissions 7 percent below the 1990 levels. When 55 countries, including a significant portion of the industrialized countries, formally ratify the agreement, it will take effect. Some key concepts that need to be fully defined include emissions trading, emissions banking, sinks, and clean development. How these strategies can be used to meet transportation goals needs to be explored.

Climate change is a global problem, and all countries must work together. The industrialized nations must take the first steps, but developing countries must also be a part of the solution. This is especially important because as manufacturing, deforestation, and automobile use increase in developing countries, their emissions could meet or exceed those of the industrialized countries. The developing countries will continue to work toward specific goals at the next meeting in Buenos Aires in the fall. The Kyoto Protocol to the United Nations Framework Convention on Climate Change, which was drafted at the meeting, may not be submitted to the U.S. Congress for approval until after the developing countries set their goals.

The impacts of the Kyoto proposals on current polices are now being assessed. We do not know what share of the burden the transportation sector will bear to meet the goals; however, it is clear that the United States is committed to accelerating and focusing efforts in the meantime. The Clinton administration has proposed $6.3 billion over five years for tax credits and for research and development to address global climate change. The proposal includes tax incentives for individuals to purchase highly fuel-efficient cars and research to develop next-generation vehicles that are three times more fuel-efficient.

What Are the Next Steps to Meet This Challenge?

One outcome of Kyoto may be that transportation will be establishing a preliminary benchmark to reduce its pro rata share of greenhouse gas emissions. To be ready to meet such a challenge, we must take a strategic approach to focus on research that will provide the greatest payoff, including research in fuels, engine technology, travel behavior, and land use. Ongoing federal programs for energy conservation will also help to address climate-change issues, such as increasing the fuel economy of cars, promoting transit and pedestrian access, reducing energy consumption in buildings, and developing alternative fuels and technologies.

These steps are a start, but to meet the challenges from Kyoto, more initiatives and programs focused specifically on sustainability will be needed. We must pursue solutions that reflect a systematic balance of the three E's -environment, economic growth, and equity. All of these factors should be considered in a systems-type approach where a change to one element would be reflected in all of the other factors.

In contrast, our current planning and decision tools often focus on short-term and site-specific impacts and health issues. For example, current air-quality programs and regulations focus on local air quality and pollutants that are affecting the health of people today. Carbon dioxide, the primary greenhouse gas, is not addressed. Often, the long-term impacts are unknown or are not factored into development or transportation decisions.

The Federal Highway Administration (FHWA) plans to take a leadership role in this emerging area and has proposed a Sustainable Transportation Initiative in the FY 1999 budget submission. This program will provide grants to state and local agencies for case studies of sustainable transportation options and develop and share best practices and decision-making processes. It will enhance current analytical tools and programs that will support sustainable transportation and focus new efforts to fill in the gaps.

One of the first requirements to achieve sustainable transportation is the development of a national consensus of our partners and stakeholders on strategies, roles, research agendas, and performance measures for sustainable transportation. There is general agreement on ways to measure greenhouse gases and other pollutants, but measures for accessibility and community impacts and equity have not been developed and will be difficult to quantify. We must work with our stakeholders to develop measures and models for evaluating performance and to identify research to develop better performance indicators that can accurately measure progress. This initiative should also foster and evaluate innovations, share best practices among the states and local governments, and enhance current planning tools and models. The initiative will also support research on advanced technologies, travel behavior, and land use.

Breakthroughs in technology hold significant promise. For example, a new advanced vehicle with intelligent vehicle systems and has zero emissions could meet sustainability criteria. Intelligent transportation systems could provide access and mobility, allow more cars to travel on the existing highways, facilitate transit service, and foster economic growth and opportunity.

With prompt action, the challenge of sustainability can become an opportunity for the United States. Our "homegrown" technologies and strategies can help solve our share of the global problem and can be marketed abroad, stimulating economic growth and promoting the competitiveness of U.S. products.

However, it would not be wise to delay other initiatives, hoping for a technological breakthrough in time. We must pursue a balanced, systems approach throughout our transportation programs. This will require a comprehensive, long-term program that aggressively develops low-emission technologies and increases the efficient uses of highway and transit facilities. The initiatives and policies must preserve economic vitality, provide flexibility that enables state and local officials to determine the best ways to meet targets, emphasize market-based solutions rather than government regulations, and support investments to research and develop technologies.

Today, the transportation community faces tremendous challenges to provide more mobility, preserve and enhance our existing systems, and improve the natural environment. It would be easy to delay the long-term issue of global climate change while we focus our attention on our immediate problems. Unfortunately, this is no longer an option. Global climate change is a long-term problem, but it demands immediate attention. The U.S. transportation community needs to join with the rest of the world on "the road from Kyoto" and do our part to create a sustainable future.

Kevin Heanue is the director of FHWA's Office of Environment and Planning. He has been with FHWA and its predecessor agencies since 1958. He has had a varied series of assignments, becoming director of environment and planning in 1990. In his present position, he is responsible for administering FHWA's programs in metropolitan and statewide planning, intermodal transportation, and the environment, including compliance with the National Environmental Policy Act of 1969 and with legislation pertaining to clean air and wetlands. Heanue is a registered professional engineer. He is active in the Transportation Research Board, the American Society of Civil Engineers, and the American Planning Association. He served as FHWA's liaison to the TRB Committee for the Study on Transportation and a Sustainable Environment. He currently serves as co-chair of the Sustainable Transportation Team for the National Science and Technology Council's Committee on Transportation Research and Development. He has a bachelor's degree in civil engineering from Tufts University in Medford, Mass., and a master's degree in civil engineering from the Georgia Institute of Technology.

Susan B. Petty is chief of the State Programs Division in FHWA's Office of Motor Carriers and is currently on detail to the Office of Planning for the development of FHWA's Sustainable Transportation Initiative. She recently completed an assignment in the Office of Policy for the development of the FHWA Strategic Plan. In her 18-year career with the Department of Transportation, Petty has had diverse experiences in highway, transit, safety, hazardous materials, pipelines, airport grants, and rail programs. She received undergraduate degrees in design and in urban studies, and she has a master's degree in public administration from North Carolina State University.

TABLES: Table 1 -Summary of TRB Scenarios for Controlling CO2 Emissions Change in growth of CO2 Over 20 years Over 40 years Baseline Scenario "Business-as-usual" assuming an increase of 1.5 percent per year in vehicle-miles traveled; no significant changes in fuel prices or economy. +35% +80% Alternative Scenarios Reduce growth in demand for motor vehicle travel by 20 percent through land-use controls, transit, and demand management, such as ridesharing, fees, and parking restrictions. -5% to -10% -10% to - 20% Raise fuel economy by 1.5 percent per year through development and deployment of fuel-saving technologies, improved traffic flow through highway operations, and intelligent transportation systems. -10% to -20% -30% to -40% Raise petroleum prices 3 percent per year to spur innovation and reduce demand through higher gas taxes, carbon tax. -10% to -20% -30% to -40% Develop low-emission technology through support and incentives for research and development and through incentives, requirements, or consumer taxes for deployment. 0 to -5% -25% to -35% Summary of scenarios presented in Special Report 215: Toward a Sustainable Future, Transportation Research Board, National Research Council, Washington, D.C., 1997, pp. 151-153.

Table 2 -Sustainable Transportation: The Next Step Forward CONTEMPORARY TRANSPORTATION THEMES EMERGING SUSTAINABLE TRANSPORTATION THEMES Metropolitan/State State/Regional/National/Global Clean Air Act/Regional Air Quality Kyoto Protocol/Global Climate Change Toxic/Criteria Pollutants Natural/Greenhouse Gases Regulation: CAFE Standards/Sport-Utility Vehicles Partnerships: Next-Generation Fuels and Vehicles New Development: Residential/Commercial/Industrial Fringe Development Redevelopment: Infill, Smart Growth, Brownfields, and Urban Growth Boundaries Mobility: Moving Vehicles, Passengers, and Freight Mobility and Access: Providing Access to Goods and Services Goal: Meet Current Highway Congestion and Capacity Needs for Mobility Goal: Balance Current and Long-Term Environmental, Economic, Equity Needs for Mobility and Access Sidebar 1: The Balance of Greenhouse Gases Greenhouse gases are an essential part of the atmosphere. When the system is balanced, the overall flow of energy from the sun is absorbed by the earth and radiated back into space as infrared energy. Greenhouse gases in the atmosphere act like a loosely woven blanket that traps and slows this flow of energy leaving the earth. About 95 percent of greenhouse gases occur naturally. These include water vapor, carbon dioxide (CO2), methane (CH4), and nitrous oxides (N2O), which are essential parts of the upper atmosphere. In addition, three synthetic gases that are now found in the stratosphere are classified as greenhouse gases: hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF6). In a balanced system, greenhouse gases are absorbed by plants, soils, and oceans. Besides water vapor, carbon dioxide is the most abundant greenhouse gas. The greenhouses gases that blanket the earth's outer atmosphere keep the mean surface temperature of the earth's surface at 15 C. Without the blanket of greenhouse gases, the surface of the earth would be about 30 C colder -too cold for most life forms. Sidebar 2: Key Terms From Kyoto Emissions trading will allow countries to trade their unused emissions reductions to other countries. Trading would be in addition to domestic actions to reduce their greenhouse gases so that all countries would be required to reduce greenhouse gases and not just rely on emissions savings from other countries. Emissions banking allows countries that surpass their commitments in a period to use these surplus reductions for future commitment periods. Sinks are natural features such as forests and oceans that absorb greenhouse gases from the atmosphere. When countries are reporting their greenhouse gas emissions, they will also report the removal of sinks because this will impact the net effect of their greenhouse gas emissions. It may also be possible for countries to help meet their commitments through reforestation and other means to create new sinks. Clean development would allow industrialized countries to provide technical and financial assistance to developing countries for sustainable development in exchange for emission credits. Sidebar 3: So, if a zero-emission vehicle was developed, would we have sustainable transportation? Unfortunately, it is not that easy. Even though the zero-emission vehicle was not contributing to global warming, other circumstances might create serious economic and social problems that would not be considered sustainable. For example: If a pollution-free vehicle was traveling on roads that were so congested that passengers and freight travel time increased dramatically. If highway fatalities and injuries increased. If parts of society did not have access to the highways, transit, or pedestrian alternatives. Sidebar 4: Components of FHWA's Proposed FY 1999 Sustainable Transportation Initiative Outreach and consensus with partners and stakeholders. Research on technology and planning tools. Grants to support states and metropolitan planning organizations for case studies of sustainable transportation options. Technical assistance and training. Sidebar 5: Equity Concerns Equity is an issue in sustainability at several levels. Globally, there is tension between developed and developing countries about the relative responsibility or share of each for greenhouse gas reductions. The United States and other countries want to ensure that the needs of the poor and the transportation-disadvantaged are given full consideration in deriving sustainable options and solutions. This includes providing access to transportation to people without a car or to the handicapped for whom a car is not a viable option.



Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000
Turner-Fairbank Highway Research Center | 6300 Georgetown Pike | McLean, VA | 22101