Assessing the Effects of Freight Movement on Air Quality at the National and Regional Level
The U.S. economy is dependent on an efficient and reliable freight transportation system. Our highways, ports, waterways, railways, airports, and intermodal facilities make up a complex system that shippers rely on to move products to markets. The performance of that system has direct implications for the productivity of the U.S. and regional economies, the costs of goods and services, and the global competitiveness of our industries. Yet, there is significant and growing concern on the part of both the private and public sectors about the future performance of our freight transportation system. Consider the following trends:
- Growth in highway travel, and truck travel in particular, has far outpaced highway capacity additions over the last two decades. While the extent of the nation's roadway system is impressive, highway lane miles increased by only 3 percent between 1983 and 2003. During this period, passenger VMT grew by 73 percent and truck VMT grew by 86 percent1. This has contributed to a significant increase in roadway congestion. According to the Texas Transportation Institute's Urban Mobility Study, peak period delay per traveler has tripled since 1982 in the nation's 85 largest urban areas.
- Utilization of railroad track infrastructure has increased substantially in recent years, leading to significant bottlenecks in some cases. Before deregulation and the Staggers Rail Act of 1980, the rail industry was widely considered to have significant levels of excess capacity. From 1980 to 2003, however, Class I railroads consolidated from 22 carriers to seven (four of which have 96 percent of Class I revenue), and the amount of Class I rail line contracted substantially, from 271,000 to 169,000 miles, a decrease of 38 percent. During that period, Class I freight ton-miles grew by 69 percent2. A recent forecast by the American Association of State Highway and Transportation Officials (AASHTO) for the rail industry suggests that, absent significant new investment, the rail industry will not be able to handle the proportion of goods movements that it carries today, although the absolute level of freight carried by the railroads will continue to increase3. According to the AASHTO study, the rail industry is likely to lose market share to trucking, adding 15 billion truck VMT to the nation's highways.
- Globalization and growth in international trade are placing more demands on our seaports. Between 1970 and 1999, international trade's share of GDP increased from 10.7 percent to 26.9 percent. As a result, our nation's ports and channels are becoming increasingly congested as ever greater amounts of freight are moved through a system with limited means for physical capacity expansion. From 1990 to 2003, tonnage at U.S. ports increased by 11 percent, and waterborne import tonnage grew by 67 percent4. Container movements at some of the nation's largest ports are growing at an even faster pace. For example, container traffic through the Port of Los Angeles has nearly doubled in just the last five years5.
- Landside access is a problem of increasing importance to our ports and is becoming one of the primary bottlenecks for the movement of goods from ships to the rest of the transportation system. Once ships arrive at a port it makes little difference how productive the rest of the port is if goods cannot be unloaded efficiently. In 2001, several of the top 15 U.S. deepwater ports reported unacceptable flow conditions on landside elements of the intermodal access system6. Compounding this problem is the fact that many ports do not have sufficient room to expand landside access nor do they have the funds required to maintain this additional capacity if it were acquired.
- The U.S. inland waterways are an important but aging component of the nation's transportation system. These waterways transport approximately 20 percent of the nation's coal and 60 percent of the nation's grain movements. Investment in the infrastructure (e.g., locks) required to support these waterways has not been adequate to maintain the system. In 1997, the U.S. Army Corps of Engineers reported that the median age of all lock chambers was 35 years. This survey also concluded that lock-specific delays have been increasing throughout the inland waterway system, and that delays averaged around six hours at the most congested locks and sometimes much longer.
- Air freight is by far the fastest growing mode of freight transportation. Domestic air cargo ton-miles increased by more than 5 percent annually between 1980 and 20037. Available forecasts predict air freight will continue to grow at rates of 4.0 percent to 5.2 percent through 2020. Growth at these rates will put considerable strain on an aviation system already characterized by frequent delays, traffic control safety concerns, and heightened security measures. To date, however, this growth in air freight has yet to severely constrain the system as a whole, although certain hubs are beginning to experience chronic problems. In the first eight months of 2004, for example, more than 30 percent of arrivals and departures at Chicago O'Hare were delayed in excess of 15 minutes or cancelled8.
Prompted by these trends, federal, state, and local agencies are undertaking a variety of initiatives to ensure that the performance of the nation's freight system does not significantly deteriorate. For example, government agencies are exploring a variety of opportunities to fund freight system improvements, including expanded use of discretionary surface transportation funds, new public-private partnerships, and development of new sources of revenue for freight projects. Metropolitan Planning Organizations (MPOs) and state Departments of Transportation (DOTs) are working to mainstream freight into the transportation planning and programming process. Integration efforts include greater involvement of freight stakeholders throughout the planning process, application of project selection criteria that explicitly account for freight benefits, and use of performance measures to track progress toward freight mobility goals. At the federal level, the Federal Highway Administration (FHWA) and other agencies are supporting professional development related to freight transportation through training and information sharing; federal agencies are also developing a number of analytical tools to assist in freight transportation planning and impact assessment.
As freight becomes more integrated into the transportation planning and programming process, there is greater need to consider the air quality impacts of freight at all stages of planning and project development. Over the last two decades, freight has become a more significant source of air pollution. One reason for this is the robust growth in freight activity described above. The other factor is the relatively less stringent regulation on emissions from the freight sector compared to passenger vehicles. Although the U.S. Environmental Protection Agency (EPA) has recently issued strict new nitrogen oxides (NOx) and particulate matter (PM) emission standards for heavy-duty trucks, these standards do not begin to take effect until 2007 and then will take some time to ripple throughout the nation's truck fleet. The major non-road freight modes (locomotives and marine vessels) were virtually unregulated until the late 1990s, and today remain much less regulated than on-road sources. Fortunately, many locomotives, ships, and aircraft have become more fuel efficient over time, which tends to reduce pollutant emissions.
The implications of these trends can be summarized as follows:
- As a result of technological and operational improvements, freight transportation has generally become more fuel efficient in terms of fuel use per ton-mile of freight moved. Fuel efficiency gains are greatest in air and rail modes9.
- Due to efficiency gains and emission regulations, freight pollutant emissions per mile and per ton-mile are generally declining. However, these emission rates are declining more for trucks than for the other freight modes10.
- The growth in freight transportation activity has, in some cases, outpaced the decline in per vehicle emission rates. For example, total U.S. NOx emissions from trucking, commercial marine vessels, and aircraft have risen over the last 20 years11. In other cases, the decline in emission rates has more than compensated for growth in freight activity and led to a drop in total U.S. emissions, particularly volatile organic compounds (VOCs) and carbon monoxide (CO).
- Pollutant emissions from other major sources, such as light duty vehicles and power plants, are declining in many cases12. As a result, freight transportation is contributing a growing share of the total emissions of some pollutants. For example, freight was responsible for 20 percent of the nation's total NOx emissions in 1980; today that percentage is 27 percent13.
At the same time that freight transportation's contribution to air pollution is growing, there is a heightened concern about the health and environmental effects of diesel engine emissions. Most freight trucks, locomotives, and ships are powered by diesel engines, which are a major source of emissions of NOx and PM. Freight transportation is also a large and growing source of greenhouse gas (GHG) emissions that contribute to global climate change, particularly carbon dioxide (CO2) emissions. These concerns, and the implementation of the 8-hour ozone and fine particulate (PM-2.5) standards, will require many regions across the country to find new ways to control NOx and PM emissions from freight transportation sources.
This study is intended to help fill a void in the current understanding of the air quality impacts of freight transportation. A large body of research has looked at multimodal freight flows from a transportation and economic perspective, and many other studies have examined the air quality impacts of freight transportation for a single mode. A smaller number of studies have compared fuel efficiency or emissions across two or more freight modes in an intercity context, but very few studies have examined freight transportation and emissions within urban areas. Furthermore, emission inventories prepared for air quality planning purposes, many of which were reviewed for this study, typically do not distinguish between freight and non-freight activity and may not allow comparison across modes or cities.
This report discusses freight transportation activity and emissions at the national level and in six metropolitan areas (Baltimore, Chicago, Dallas-Fort Worth, Detroit, Houston, and Los Angeles). The report draws on a variety of existing studies and data sources and develops new emissions estimates to fill data gaps. The study findings were documented in six detailed technical memoranda prepared by ICF Consulting for FHWA over the course of 2004. This report presents selected highlights from those memoranda.
The remainder of this report is organized into four sections:
- Chapter 2 reviews freight transportation activity and emissions at the national level, including freight movement trends by mode, emissions standards that affect freight transportation, and national-level emissions from freight transportation.
- Chapter 3 presents estimates of freight transportation emissions in the six study areas by mode, including trucking, freight rail, marine vessels, port cargo handling equipment, aircraft, and airport ground support equipment.
- Chapter 4 describes strategies to reduce emissions from freight transportation, including technology-oriented strategies and operational strategies.
- Chapter 5 discusses conclusions and recommendations for future research.
Several appendices (Appendix A, Appendix B, Appendix C) provide supporting technical information.