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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy 3 Mitigation Research to Inform Policy and Practice The mitigation strategies of primary interest to this study are opportunities to (a) reduce travel on vehicles and modes with high emissions of greenhouse gases (GHGs) and (b) shift travel to modes with lower emissions. The climate change bill that passed the House of Representatives in June 2009, the similar Senate bill proposed in October 2009 by Chairman Boxer of the Environment and Public Works Committee and Senator Kerry, and the transportation reauthorization legislation introduced by Chairman Oberstar of the Transportation and Infrastructure Committee all would require new federal, state, and regional efforts to plan for and reduce transportation GHG emissions, over and above the reductions that will come from more fuel-efficient vehicles. Moreover, reauthorization legislation introduced in the Senate by Chairman Rockefeller and Senator Lautenberg of the Commerce Committee would require reductions in per capita travel, a provision that 60 members of the House have endorsed. Many states have also committed to reducing travel. Because travel and economic growth are so tightly linked, however, an understanding of the potential impacts of such policies on economic growth as well as on GHG emissions is important. Unfortunately, little guidance about the effectiveness and costs of various transportation mitigation policies to save energy and reduce GHG emissions is available, although such information is beginning to be produced (Cambridge Systematics 2009; Center for Clean Air Policy 2009).1 1 Both of these reports appeared late in the committee’s deliberations. Information about the assumptions and methods behind the estimates in the Cambridge Systematics (2009) report, which covers a broad array of mitigation measures, was not available for review at the time of this writing.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy This chapter first provides a broad overview of strategies to make travel more energy efficient and identifies areas of uncertainty that research could address. It then indicates areas in which research is needed and describes criteria for how such research should be organized and managed. INTRODUCTION As an organizing scheme, it is useful to think about reducing transportation GHG emissions and energy consumption on the basis of a framework initially developed by Schipper et al. (2000) and employed by Eads (2008). The amount of CO2 emissions from fuel combustion by transport can be represented as follows: where G = CO2 emissions (or GHG emissions) from fuel combustion by transport, A = total transport activity, Si = modal structure of transport activity, Ii = energy consumption (fuel intensity) of each transport mode, and Fi,j = sum of GHG emissions characteristics of each transport fuel used by various modes (i = transport mode, j = fuel type). Understanding the potential value of mitigating transportation GHG emissions and reducing energy consumption requires examination of each of these variables. A = total transport activity, which is a function of growth in gross domestic product (GDP) and population. It is also influenced by development and trade patterns (which determine the distance between origins and destinations). S = modal structure of transport activity. Strong growth has occurred in recent decades in aviation, in the freight mode share of trucks compared with rail and water, and in light-duty vehicle (LDV) (cars, SUVs, and pickup trucks used for personal travel) use compared with transit.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy I = energy consumption or fuel intensity of modes, which has stagnated in the highway mode in the United States for the past 25 or so years, a period when fuel prices were low and policy makers were unwilling to require increases in LDV corporate average fuel economy (CAFE) standards.2 F = GHG emissions characteristics of modes and fuel types. Virtually all forms of U.S. transportation rely on petroleum-based fuels; thus, transportation GHG emissions are highly correlated with total fuel consumed. Not only the amount of activity and vehicle energy intensity but also the operation, construction, and maintenance of the infrastructure itself have energy and GHG emission consequences. This chapter will focus primarily on research opportunities to affect total transport activity, mode structure, and energy consumption through changes in travel demand; the role that infrastructure construction, operations, and maintenance might play in energy and emission reductions will be touched on. A brief overview of vehicle fuel intensity and emissions characteristics is also provided to help place these topics in perspective. TRANSPORTATION ACTIVITY Total transportation activity is closely related to the national economy, population change, and development patterns. Although legislative goals call for reductions in energy consumption and GHG emissions from transportation, most projections assume that U.S. passenger and freight travel will increase as the economy, population, and built environment expand.3 The section that follows gives an overview of the influences of population and economic growth and changes in urban form on travel 2 The latter has changed with the passage in 2007 of sharply increased CAFE standards, which are intended to improve LDV new fleet fuel economy to 35 mpg by 2020, and with the announcement of the Obama administration in May 2009 that it would accelerate achievement of these standards to 2016. 3 See, for example, the Department of Energy’s Annual Energy Outlook 2009, whose forecast of a 10 percent increase in transportation energy consumption over current levels by 2030 is based on assumptions about economic and population growth. http://www.eia.doe.gov/oiaf/aeo/, accessed July 7, 2009.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy demand. This is followed by a description of a broad set of options for moderating growth in travel and of the gaps in knowledge about how well such strategies might perform. Background Transportation both contributes to economic growth and is influenced by GDP as incomes rise (Eads 2008). The relationship between per capita real income and per capita travel can be expected to change as advanced industrialized nations shift to service economies. As a general rule, however, per capita real incomes are highest in nations with the most per capita travel (e.g., in North America) (Eads 2008, 219). One obvious way to reduce transport GHG emissions is to reduce travel or at least the rate of growth in vehicle miles of travel (VMT), but care must be taken in doing so to avoid harming economic activity. The American Association of State Highway and Transportation Officials has indicated that the highway system cannot manage more than 1 percent annual growth in VMT over the next two or three decades because of expected limited capacity growth; hence, efforts to moderate VMT growth may be necessary for reasons other than GHG mitigation, especially congestion management. Environmental advocates go a step further, seeking actual reductions in VMT through increases in the cost of travel and changes in urban form, which are discussed below. Population growth will increase total transportation activity. The U.S. Census Bureau projects that population will grow between 0.8 and 1 percent annually from 2008 to 2050, which will result in a 56 percent increase over 2008 and a net increase in population of 135 million (U.S. Census Bureau 2009, Table 3). Thus, all other things being equal, one could expect total U.S. passenger travel to increase simply because of population growth by 2050. Indeed, in past decades VMT has increased much faster than population, presumably because of rising incomes (Memmott 2007). Future travel will be affected not only by the nature of future development but also by the existing built environment, which changes slowly. Trends within and across most metropolitan areas in recent decades have generally been toward less densely developed areas. The United States is increasingly “urbanized” according to official statistics, but “suburbanized”
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy would be a better descriptor given that the formal Census Bureau definition of “urban” is areas with at least 1,000 population per square mile, which is a low threshold for development density—about 1.6 people per acre or about 0.67 houses per acre at average household occupancy rates. Under this definition, metropolitan areas are continuing to suburbanize. From 1970 to 2000, the suburban population slightly more than doubled from 52.7 million to 113 million. This growth occurred mainly at the expense of nonmetropolitan areas; population in central cities grew, but only by about 55 percent, from 44 million to 68.5 million (Giuliano et al. 2008). In terms of relative share, suburban population increased from 54.5 percent of total metropolitan population in 1970 to more than 62 percent in 2000. As of 2000, 80 percent of the total U.S. population lived in metropolitan areas, and 50 percent resided in the suburbs of these areas. As origins and destinations become farther apart, travel distances necessarily increase. Obviously, trips are shorter and more are made by transit, walking, or biking in dense urban environments such as Manhattan or central Boston than in the suburbs or exurbs of metropolitan areas or in rural areas, but the trend in preceding decades has been toward suburban development. The trend could change with changes in preferences and public policy. The ever-growing share of population growth represented by immigration and the aging of the baby boom cohort could alter preferences for suburban living (TRB 2009). Research to examine such changes and inform public policy is suggested later in this chapter. The United States has a large supply of inexpensive land, and vast distances separate population and economic centers, which depend on transportation connections. The nation’s extensive highway system, the success of motor carriers in using this ubiquitous system to capture mode share, and the aviation system have allowed economic development to spread across the nation. The locations of major centers of trade and economic activity are no longer constrained by the requirement of proximity to a water port or adjacency to a railroad. The large supply of inexpensive land means that, without changes in land use policies, even high energy prices may not discourage the location of economic activity in low-density areas, simply because the costs of development are so low in comparison. This pattern of national economic development has
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy allowed formerly less developed regions to become more prosperous but has increased the demand for transportation. If reducing total travel, or at least the growth rate of travel, becomes a policy objective for the nation, an understanding of the feasible and acceptable options for reducing travel in the most efficient ways become important. Clearly, successful implementation of policies requires that they be acceptable to a significant proportion of the public. Some broad options for addressing travel growth as well as suggestions for research areas to reduce knowledge gaps are outlined below. Options for Reducing Total Transportation Activity and Associated Research Needs In this section broad strategies to reduce total demand for transportation are reviewed. Demand would be reduced by raising the cost of travel through higher fuel taxes or pricing use of the transportation system, by changes in land use to make travel more efficient, and by use of telecommunications technology to substitute for travel. A subsequent section of this chapter discusses strategies to influence travelers to shift to more fuel-efficient modes. Reduce Motorized Vehicle Use by Raising the Cost of Fuel Imposition of carbon taxes, or increasing the cost of fuels indirectly through a carbon cap-and-trade regime, will reduce travel by making fuel more expensive. Available analysis indicates that LDV demand is fairly insensitive to increases in fuel cost, however (Small and Van Dender 2007). In the short run higher prices do not appear to reduce travel much, and in the long run consumers shift to more fuel-efficient vehicles. Carbon taxes or cap-and-trade proposals that would raise fuel prices, of the type debated in the U.S. Senate in 2008, would have minor effects on total fuel purchases and VMT in part because the impact of such proposals on fuel prices would be modest and in part because the increases in fleet fuel economy standards that Congress enacted will significantly reduce future travel costs (CBO 2008). Another reason for the limited response is that small and mobile transportation vehicles depend on fuel with high energy density, which is not the case for fixed energy users such as power plants. The latter energy users have more substitute
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy fuels at their disposal and, therefore, more cost-effective options for reducing GHG emissions. Some argue that transportation should reduce its GHG emissions in proportion to its share of total GHG emissions. Others argue that this should not be a concern as long as emission reductions are taking place in the economy through the most cost-effective responses. Indeed, for reasons explained above it is likely that carbon pricing schemes (tax or a carbon cap-and-trade system) will not exert a proportional effect on transportation even if carbon prices are set to reflect the external cost of carbon emissions, including climate-related costs. Nevertheless, policy makers may be motivated to reduce energy use in transportation for other reasons. For example, concern about imports of petroleum, often from unstable parts of the world, also motivates interest in measures to reduce transportation petroleum consumption, including measures aimed at reducing VMT. If policy makers wish to reduce total transportation demand beyond the levels that would be achieved through a carbon tax or cap-and-trade regime, questions arise concerning how much travel can be reduced and at what cost. It is largely unknown how much total personal and freight travel could be reduced, independent of changes in development and logistic patterns, without risking a reduction in GDP that is greater than the societal benefits from these actions. Clearly, some trip making is not highly valued by users but imposes higher social and environmental costs than the user is required to pay. Ideally, such travel would be the first to be reduced by pricing and other measures aimed at reducing overall VMT. Whereas people and shippers would not make or pay for trips if they did not value the end result more than the cost of the trip, it is important to ensure that they pay all of the costs. As policy makers consider proposals that would reduce both personal and freight VMT, they need information about how changes in travel affect productivity and economic growth. A fundamental problem facing all proposals to reduce VMT is a lack of understanding about how they would affect travel behavior and the economy. Little research is supported in this area through federal programs; hence, the knowledge base is limited. This topic is further discussed in the research recommendations below.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy Price Use of Transport Infrastructure Pricing strategies (congestion pricing, areawide pricing, parking, tolling, or charging for mileage traveled), while controversial, could reduce total automobile travel by causing some trips to be forgone and by encouraging mode shift. Strategies for pricing highway transportation would probably be the most effective in reducing automobile travel and encouraging mode shifts (discussed separately below), although congestion pricing may mostly serve to shift travel to less congested times and places rather than to reduce trips.4 These proposals are efficient in the sense that the affected parties decide on how best to respond. The Federal Highway Administration (FHWA) Value Pricing Program has been funding research and experimentation at the regional level on a variety of approaches such as pricing high-occupancy vehicle lanes, parking pricing, and cashing out parking. Experimentation has demonstrated the effect of pricing strategies on traffic flow, but much remains to be understood about public acceptability, equity, environmental impacts, and the appropriate institutional arrangements for carrying out pricing programs (Bhatt et al. 2008). Road pricing has been tested and implemented on a broader scale in Europe, but whether the positive experiences in London and Stockholm would translate to the United States remains uncertain (Richardson and Bae 2008, 9). There is as much need to learn about whether and how pricing strategies can be made more palatable, perhaps through strategies based on how revenues are allocated, as there is to learn what effects such strategies have on demand and GHG emissions. An understanding of the potential cost per ton of GHG emission reduction under the full range of pricing strategies is also needed. Interest in moving away from fuel taxes as the main revenue source for transportation trust funds to a charge on motorists for mileage traveled is growing. With such a system, the mileage rate charged could be 4 The trial imposition of congestion fees in central Stockholm during 2006, for example, reduced total work and school trips by automobile into the central area, but virtually all these work trips shifted to transit (Eliasson et al. 2009, 245). In contrast, peak-period discretionary automobile trips (equal in number to work and school trips) made before the imposition of the charge did not shift to transit. The study was unable to determine whether the trips were canceled, delayed, substituted for, or combined with other trips.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy adjusted to reflect environmental values. For example, some mileage charging approaches would permit supplemental charges based on vehicle fuel economy. If such a regime could result in a systemwide approach to charging for road use, road pricing across all road classes would be technically feasible. Appendix A describes research and demonstration programs that would test alternative mileage charging technologies and engage the public and key stakeholders in a process to determine the acceptability of such an approach. Change Urban Development Patterns The National Research Council (NRC) committee that produced estimates of GHG reduction and energy savings that would be achieved by a doubling of the residential density of 25 to 75 percent of future residential development by 2050 indicates that the effects will be modest (TRB 2009). The scenarios in that report indicate that such changes could result in reductions in VMT, energy consumption, and CO2 emissions ranging from less than 1 to 11 percent by 2050, although the committee disagreed about the plausibility of achieving a doubling of density for 75 percent of future development. Policy makers wishing to achieve decreases in VMT through urban form and transit investment strategies need to know much more about the ingredients necessary for success of such strategies and what their benefits and costs might be. Research has shown that a blend of regulation, design, and investment in alternative modes is necessary for achievement of successful compact, mixed-use development, but which elements are necessary and to what degree, and how they vary across different urban forms, are unknown. Successful smart growth has included allowance for mixed uses (stores, offices, and housing located together rather than separated), investments in improved transit accessibility, better physical design to encourage and support walking, and parking pricing and changes in zoning to constrain maximum parking rather than mandate minimum parking. What is not well understood is the precise formula, how it might apply in different metropolitan areas, or what it would cost. There are very considerable differences in how metropolitan areas are developing (Lee 2007; Giuliano et al. 2008). Atlanta’s urban form, which is typical of fast-growing, sprawling metropolitan areas in
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy the South, differs from that of areas such as New York City, Boston, Chicago, or even San Francisco and Los Angeles. Transit-supportive strategies for compact development that work well for older cities with central business districts built up before the automobile or constrained from expanding by topography would not necessarily be appropriate for Atlanta or Houston. Research to address such questions would focus on detailed case studies of successes and failures of explicit transportation–land use strategies. A complete scholarly analysis of the successes that Portland, Oregon, has achieved would be especially valuable. Portland’s success has apparently been the result of several factors: strong state leadership, state growth management policies with an urban growth boundary as part of these policies, a regional government with strong influence over municipal land use and transit planning and investment, a young workforce with a fast-growing high-tech industry, political consensus on growth policy, and others. Insight into the measures needed to replicate Portland’s experience elsewhere would be useful to policy makers. To the extent that the measures used in Portland have been applied elsewhere, it would be valuable to know whether they succeeded or failed, and why. Better tools are also needed by metropolitan planning organizations (MPOs) to analyze transportation and land use options for regional policy makers. [This is in large part a demonstration and technology transfer problem; sophisticated linked travel and land use models are employed in a few places, but they are not employed by many MPOs (TRB 2007).] TRB’s 2007 study on travel model practice in MPOs recommended research, technology demonstrations, and technology transfer to improve modeling and the state of practice. Such model improvements will become essential if states and regions must analyze the effects of various taxes, fees, regulations, and other policies on travel. At a more fundamental level, MPOs need much better models to capture behavioral responses. Models of trip generation need to become much more sensitive to how people change their trip making as circumstances change. In turn, development of such models requires more fundamental research into travel behavior (described later in this chapter). Models of intrametropolitan area freight travel and the data on which they are based are even less well developed.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy Many advocates of smart growth believe that this form of development has many ancillary benefits—closer community ties, more affordable housing, healthier lifestyles, and so forth. Whether the changes would all be beneficial is uncertain since families would also be giving up some of the housing size, privacy, and open space that come with low-density development. A way to measure (better than do stated preference surveys) how different physical environments, including different transportation infrastructure and operations, affect well-being is needed. Analysis of the cost per ton of GHG emissions reduced by smart growth development should be accompanied by estimates of the other social and economic benefits and costs of this form of development. As a general rule, little is understood concerning what might be thought of as “second-order” effects that might result from more efficient transportation and development. Would the coupling of such outcomes have significant multiplier effects? Use Technology to Substitute for Trips Telecommuting, videoconferencing, Internet shopping, and the widespread availability of information and communications technologies (ICTs) all appear to have the potential to substitute for or reduce travel. The relationships between travel and ICTs are more complex than is commonly assumed; there are as many arguments for how ICTs stimulate additional travel as for how ICTs reduce it (Mokhtarian 2009). Research has not provided any empirical evidence that telecommunications, on a net basis, substitute for private vehicle trips (Choo et al. 2007), although there is evidence of a modest impact in telecommuting (Choo et al. 2005). Good evidence of how ICTs affect total travel or whether they stimulate or substitute for travel is not yet available. Development of research methods is needed in this area, along with better understanding of how information and communications can substitute for trips. The need for such knowledge confirms the importance of the fundamental research program recommended later in this chapter. Summary Strategies are available that would affect demand in ways that could help achieve energy and climate goals efficiently, but understanding of their
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy they require analysis of options over a much longer time period than the 20- or 30-year horizon often used in transportation planning exercises. Adopting a long-range perspective introduces deep uncertainties about the effects of climate and technological change and how societies will respond. Methods are in development that incorporate these uncertainties into models that guide policy makers through consideration of a wide range of possible futures and adaptive strategies (Lempert et al. 2003). The choices such exercises develop for the long term can be very different from those that seem appropriate over analysis periods of only 10 or 20 years. Dewar and Wachs (2006) have suggested how these approaches to incorporating uncertainty could be applied to transportation planning in response to climate change. They criticize the transportation models currently used for regional and state long-range planning for their deterministic nature and inability to incorporate the uncertainties that characterize the challenges of responding to climate change. Fundamental research on such modeling approaches would address how they might be developed to analyze transportation policy options to respond to climate change over the long term, taking into account uncertainties about climate, technological, social, and economic changes. Policy Analysis Grouped together under this heading are a variety of analytical tasks needed to inform policy makers: Successes and failures of past transportation interventions to meet federal air quality standards: For nearly 40 years the nation has struggled to reach national air quality standards through transportation and other measures. The mitigation strategies to reduce GHG emissions are similar to those implemented to reduce criteria emissions from vehicles. Many of these strategies are embedded in the existing federal–state policy framework, but whether they are all effective is an open question. Clearly, vehicle emissions and CAFE standards have gone a long way toward meeting Clean Air Act goals. Mandates to reduce ozone precursors have been effective in requiring local officials to become creative in addressing problems, but the so-called conformity test remains controversial. Much could be gained from
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy scholarly evaluations of the effectiveness, costs, feasibility, and acceptability of past interventions. Lessons from abroad: Most industrialized nations are already engaged in mitigating transportation emissions. Although international comparisons can be fraught with problems, much can be learned if the research is well designed. Much can also be learned about how other nations organize research to provide local policy makers with information that will help them implement the most cost-effective GHG-reducing strategies at the local level.13 Implementing user charges: The discussion of full social cost accounting above describes the need for research to improve the ability to quantify difficult-to-value social and environmental costs. Even if they were better known, there is a political reluctance to impose such costs. International experience with cordon tolls indicates that public support for pricing measures improves once they are implemented. The introduction of congestion pricing in Stockholm through a pilot program before the holding of a public referendum appears to have shifted support to a majority position. These examples need to be examined more closely to improve understanding of how public acceptance was achieved. More generally, research is needed to improve understanding of whether and how the public might accept marginal social cost approaches in any sector and to suggest strategies that might help move society in this direction for pricing transportation. In addition, many regulatory approaches, such as motor vehicle fuel economy standards and safety standards, have the effect of raising prices to require consumers to pay for social costs they might not fully value. Although these approaches are less efficient, they do not suffer from the same broad lack of public support as do pricing measures. The merits of these kinds of approaches should be evaluated. Integrated vehicle–fuel scenarios: As indicated in the section on vehicle and fuel energy intensity, there will be an ongoing need for assessments of the potential of alternative vehicles and fuels to meet GHG emission reduction targets. As useful as such analyses are, they often have to make simplifying assumptions that may not prove realistic. 13 For example, May et al. (2008) describe how the United Kingdom developed a research initiative to help local officials make informed decisions about urban transportation and land use strategies.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy Refinements can be made through research to integrate more fully all the required dimensions of cost, rate of technology innovation, safety, performance, and so forth. Equity: Many of the potentially most effective strategies aimed at modifying travel behavior involve increasing the cost of driving, which could be inequitable. There are surely ways to minimize inequitable impacts, but they are not always the obvious ones (Schweitzer and Taylor 2008). Sales taxes, for example, which are increasingly levied as an alternative to raising gasoline taxes, can place an extra burden on the poor. Research and analysis can lead to the design of policies to meet GHG emission reduction goals without placing a special burden on the least advantaged. Institutions: Enacting policies that would result in significant changes in travel behavior may also require significant changes in institutions that develop such policies. Regional strategies are required in addressing travel behavior at the metropolitan scale, but MPOs are weak institutions, and most have little influence over land use policy within their regions. Furthermore, transit authorities and state, county, and city highway departments are responsive to differing legislative mandates and funding streams. Harmonizing these institutions at the regional scale is a difficult challenge that few regions have mastered. Research could inform policy makers about the consequences of reforms that have been tried in some regions. Benefits of new investments in less energy-intensive modes: Transit has the potential to save energy, particularly in places that support efficient and cost-effective transit. Transit currently captures about 11 percent of metropolitan area work trips and only 2 percent of trips overall, but it captures 23 percent of work trips in central cities of 5 million or more (Pisarski 2006, Table 3-23). Of course, a massive expansion of transit would be required to make a significant dent in the GHG emissions of passenger vehicles overall, given the small share of total trips that transit represents. Analysis of the particular settings in which transit strategies pay off in terms of energy savings and GHG emission reductions is needed. Rail transit systems have better fuel efficiency per passenger mile than do buses. However, they are capital intensive and take decades to plan and build out to a system level, and subways require enor-
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy mous energy to construct. The best near-term opportunities exist in places that already have rail systems, so research should focus initially on where and how system expansions make the most sense from a GHG-reduction perspective. Although intercity passenger rail is about 24 percent more energy efficient than LDVs, expansion of the passenger rail network is problematic for a number of reasons. New rights-of-way for high-speed passenger rail are expensive, are difficult to obtain because of the required nearly straight and level alignments, and face significant environmental barriers. The energy costs required for the construction of the new capacity also need to be considered.14 Program evaluation: If the experience with the Clean Air Act is a guide, some programs implemented to influence travel will not work or will not be as effective as needed. Interventions should be rigorously evaluated by independent researchers so that ineffective programs can be discarded and potentially more effective ones implemented. National-level analysis: In addition to the topics suggested above, there is a need to encourage consideration of broad, national-level strategies that encompass all of transportation—travel demand, vehicle technologies, alternative fuels, substitutes for travel—to address fundamental questions of how the transportation system, considered as a whole, could respond to the problem of climate change. The intent would be to encourage creative reconsideration of how transportation is conceived and provided in a world where carbon emissions are a binding constraint. System Management and Operations Many regions have implemented elements of intelligent transportation system technologies that could allow greater fine-tuning of traffic flows. To achieve the 20 percent GHG emission reduction potential cited earlier, 14 Almost all intercity rail now operates on tracks that service both passenger and freight trains. This makes introduction of intercity passenger rail more feasible, but it reduces the speed at which passenger trains can operate and raises safety concerns. Most intercity rail lines are owned by private freight railroads, and many corridors operate near capacity for freight alone. For safety and capacity reasons, private railroads are not anxious to share tracks with passenger trains. Policy makers need information about the potential of intercity rail—particularly the cost per ton of GHGs reduced when the costs of obtaining rights-of-way, addressing safety issues, and other issues are included.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy information would probably have to be combined with speed management in ways that are becoming more common in Europe but that are not being used in the United States. Among other possibilities are more intensive management of freeway access to reduce congestion, improved incident and special event management, and real-time travel information (see Burbank 2009, Appendix A). Research on advances in these areas is needed to inform managers about the potential of different strategies, to evaluate new strategies when they are tried, and to share information with others. Materials, Maintenance, and Construction Research is already under way worldwide on new forms of concrete with lower GHG emissions during cement production, and asphalt pavers are already adopting European warm-mix asphalt practices that require less energy to produce and deploy. New paving materials, of course, also have to meet performance and durability standards, so evaluating these new products will remain an important line of research. The benefits from a life-cycle maintenance and GHG emission reduction perspective of switching to illumination with light-emitting diodes should be investigated. Largely underinvestigated are practices that could substantially reduce energy requirements for maintenance, such as median and right-of-way plantings that require less energy for mowing. The energy required for construction and whether there are opportunities for major savings in this area are also largely underinvestigated. Structure The committee concurs with Burbank’s recommendation that the fundamental research identified above should be organized along the National Science Foundation model. Under this approach, proposals would be solicited through Broad Agency Announcements (BAAs) within each topic area, the proposals would be evaluated by expert peers, only the best proposals would be funded, and the research results would be peer reviewed before publication. The illustrative topics described above are meant to identify promising areas of inquiry to inform future policy decisions. It is expected that the BAAs would identify such areas as in need of research and that the research undertaken would be based on the quality of the proposals submitted, as judged by peers in a merit review process.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy CONCLUSIONS The effects of expected population and economic growth on transportation demand and the importance of transportation in meeting social needs will make mitigation of GHG emissions and the saving of energy in the transportation sector extraordinarily challenging. Expected improvements in technologies and fuels could make reducing transportation energy consumption and GHG emissions by 2050 to the levels of 1990 or 2000 possible, although such a goal will be difficult to achieve. Reducing them another 60 to 80 percent, if required, may not be feasible with technology and fuels alone, hence the frequent calls for reducing future travel demand or shifting it to more fuel-efficient modes. Significant carbon taxes or a carbon cap-and-trade program resulting in elevated fuel prices will stimulate demand for new vehicles and fuels. These fuel prices can be set by policy without necessarily investing more tax dollars in research on travel behavior. However, if policy makers determine that significant reductions in future travel demand are necessary, the selection of the most effective and beneficial strategies will be critical, because reductions in travel by themselves can be harmful to economic and social welfare. Unfortunately, the knowledge base for advising policy makers in this area is weak. Basic research in the area of travel behavior has not been supported, and data for policy analysis have many gaps and flaws. Investments in surface transportation mitigation research in two main areas are recommended in this chapter. The first would provide initial guidance to policy makers and practitioners and help shape the direction of the other recommended research areas. It would also develop information and guidance for policy makers and administrators about strategies that can be implemented on the basis of available information. Transportation policy decisions are made by the federal government, all 50 states, and tens of thousands of cities and counties, and land use decisions are typically guided at the metropolitan scale but enacted at the city and county scales. Thus, the audience for this research is broad and has diverse responsibilities. Under this program, guidance would be continually updated as new data are collected and research results are provided from the recommended fundamental research program, and outreach activities to state and local decision makers would be conducted. The second would guide the conduct of the fundamental research recommended
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy earlier in the chapter, which would provide new information and insight for policy analysis and guidance. As important as identifying topics for research is managing the research in a way that is most effective in asking the right questions and employing rigorous quality control measures. Asking the right questions requires that programs be shaped by stakeholders. Employing the most rigorous quality-control measures requires allocating funds to the best among competitively solicited proposals, with awards being based on merit and decisions being made by peers. Criteria for organizing and administering a research program that meets these standards are described in Chapter 5. REFERENCES Abbreviations BTS Bureau of Transportation Statistics CBO Congressional Budget Office NRC National Research Council TRB Transportation Research Board Babcock, M., and J. Bunch. 2007. Energy Use and Pollutant Emissions Impacts of Shortline Railroad Abandonment. In Research in Transportation Economics, Vol. 20, Railroad Economics (S. Dennis and W. Talley, eds.), Elsevier. Barth, M., and K. Boriboonsomsin. 2008. Real-World Carbon Dioxide Impacts of Traffic Congestion. In Transportation Research Record: Journal of the Transportation Research Board, No. 2058, Transportation Research Board of the National Academies, Washington, D.C., pp. 163–171. Bhatt, K., T. Higgins, J. T. Berg, J. Buxbaum, and E. Enarson-Hering. 2008. Value Pricing Pilot Program: Lessons Learned. Federal Highway Administration, U.S. Department of Transportation. http://www.ops.fhwa.dot.gov/publications/fhwahop08023/vppp_lessonslearned.pdf. Accessed July 7, 2009. Bronzini, M. S. 2008. Relationships Between Land Use and Freight and Commercial Truck Traffic in Metropolitan Areas. Transportation Research Board of the National Academies, Washington, D.C. BTS. 2007. BTS Special Report: A Decade of Growth in Domestic Freight Rail and Truck Ton-Miles Continue to Rise. SR-002. Research and Innovative Technology Administration, U.S. Department of Transportation, July. Burbank, C. J. 2009. Greenhouse Gas (GHG) and Energy Mitigation for the Transportation Sector: Recommended Research and Evaluation Program. Transportation Research Board of the National Academies, Washington, D.C.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy Cambridge Systematics, Inc. 2009. Moving Cooler: An Analysis of Transportation Strategies for Reducing Greenhouse Gas Emissions. Urban Land Institute, Washington, D.C., July. CBO. 2008. Climate-Change Policy and CO2 Emissions from Passenger Vehicles. Economic and Budget Issue Brief, Washington, D.C., Oct. Center for Clean Air Policy. 2009. Cost-Effective GHG Reductions Through Smart Growth and Improved Transportation Choices: An Economic Case for Investment of Cap and Trade Revenues. Washington, D.C., June. http://www.ccap.org/docs/resources/677/CCAP%20Smart%20Growth%20-$%20per%20ton%20CO2%20(June%202009)%20FINAL%202.pdf. Accessed July 1, 2009. Chester, M., and A. Horvath. 2008. Environmental Life-Cycle Assessment of Passenger Transportation: A Detailed Methodology for Energy, Greenhouse Gas and Criteria Pollutant Inventories of Automobiles, Buses, Light Rail, Heavy Rail, and Air, Vol. 2. http://www.sustainable-transportation.com/. Accessed April 13, 2009. Choo, S., T. Lee, and P. L. Mokhtarian. 2007. Do Transportation and Communications Tend to Be Substitutes, Complements, or Neither? U.S. Consumer Expenditures Perspective, 1984–2002. In Transportation Research Record: Journal of the Transportation Research Board, No. 2010, Transportation Research Board of the National Academies, Washington, D.C., pp. 121–132. Choo, S., P. Mokhtarian, and I. Salamon. 2005. Does Telecommuting Reduce Vehicle-Miles of Travel? An Aggregate Time Series Analysis for the U.S. Transportation, Vol. 32, No. 1, pp. 37–64. Davis, S. C., S. W. Diegel, and R. G. Boundy. 2009. Transportation Energy Data Book, 28th ed. ORNL-6984. Prepared by Oak Ridge National Laboratory for the U.S. Department of Energy, Washington, D.C. http://www-cta.ornl.gov/data/Index.shtml. Delucchi, M. 2003. A Lifecycle Emissions Model (LEM): Lifecycle Emissions from Transportation Fuels, Motor Vehicles, Transportation Modes, Electricity Use, Heating and Cooking Fuels, and Materials. Paper UCD-ITS-RR-03-17. Institute of Transportation Studies, University of California at Davis. http://www.its.ucdavis.edu/people/faculty/delucchi/index.php#LifecycleEmissions. Accessed Sept. 22, 2009. Dewar, J. A., and M. Wachs. 2006. Transportation Planning, Climate Change, and Decision-making Under Uncertainty. Transportation Research Board of the National Academies, Washington, D.C. http://onlinepubs.trb.org/onlinepubs/sr/sr290DewarWachs.pdf. Accessed Sept. 15, 2009. Eads, G. C. 2008. Contribution of U.S. Transportation Sector to Greenhouse Gas Emissions and Assessment of Mitigation Strategies. In Special Report 290: Potential Impacts of Climate Change on U.S. Transportation, Transportation Research Board of the National Academies, Washington, D.C., pp. 210–266. Eliasson, J., L. Hlutkrantz, L. Nerhagaen, and L. Rosqvist. 2009. The Stockholm Congestion-Charging Trial 2006: Overview of Effects. Transportation Research A, Vol. 43, pp. 240–250.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy Giuliano, G., A. Agarwal, and C. Redfearn. 2008. Metropolitan Spatial Trends in Employment and Housing: Literature Review. Transportation Research Board of the National Academies, Washington, D.C., Sept. Heywood, J., A. Bandivadekar, K. Bodek, L. Cheah, C. Evans, T. Groode, E. Kasseris, M. Kromer, and M. Weiss. 2008. On the Road in 2035: Reducing Transportation’s Petroleum Consumption and GHG Emissions. Laboratory for Energy and the Environment, Massachusetts Institute of Technology, Cambridge, July. Hu, P. S., and T. R. Reuscher. 2004. Summary of Travel Trends: 2001 National Household Travel Survey. Federal Highway Administration, U.S. Department of Transportation, Washington, D.C. http://nhts.ornl.gov/2001/pub/STT.pdf. Accessed April 12, 2009. Jamin, S., A. Schafer, M. Ben-Akiva, and I. Waitz. 2004. Aviation Emissions and Abatement Policies in the United States: A City-Pair Analysis. Transportation Research D, Vol. 9, No. 4, July. Lave, C. A. 1977. Rail Rapid Transit and Energy: The Adverse Effects. In Transportation Research Record 648, Transportation Research Board, National Research Council, Washington, D.C., pp. 14–30. Lee, B. 2007. “Edge” or “Edgeless” Cities? Urban Spatial Structure in U.S. Metropolitan Areas, 1980–2000. Journal of Regional Science, Vol. 47, No. 3, pp. 479–515. Lempert, R., S. Popper, and S. Bankes. 2003. Shaping the Next 100 Years: New Methods for Long Range Quantitative Policy Analysis. Rand, Santa Monica, Calif. Levine, J. 2006. Zoned Out: Regulation, Markets, and Choices in Transportation and Metropolitan Land Use. Resources for the Future, Washington, D.C. Levinson, D. 1996. The Full Cost of Intercity Travel: A Comparison of Air, Highway, and High-Speed Rail. Access No. 9, University of California Transportation Center, Berkeley, Fall. Lutsey, N., and D. Sperling. 2009. Greenhouse Gas Mitigation Supply Curve for the United States for Transport Versus Other Sectors. Transportation Research D, Vol. 14, No. 3, May. May, A. D., M. Page, and A. Hull. 2008. Developing a Set of Decision Support Tools for Sustainable Urban Transport in the U.K. Transport Policy, Vol. 15, No. 6, pp. 328–340. Memmott, J. 2007. Trends in Personal Income and Passenger Vehicle Miles. SR-006. Bureau of Transportation Statistics, Research and Innovative Technology Administration, U.S. Department of Transportation, Oct. Mokhtarian, P. 2009. If Telecommunication Is Such a Good Substitute for Travel, Why Does Congestion Continue to Get Worse? Transportation Letters, Vol. 1, pp. 1–17. NRC. 2008. Transition to Alternative Transportation Technologies—A Focus on Hydrogen. National Academies, Washington, D.C. Pisarski, A. E. 2006. Commuting in America III: The Third National Report on Commuting Patterns and Trends. Transportation Research Board of the National Academies, Washington, D.C.
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A Transportation Research Program for Mitigating and Adapting to Climate Change and Conserving Energy Plotkin, S., and M. Singh. 2009. Multi-Path Transportation Futures Study: Vehicle Characterization and Scenario Analyses. Draft. Argonne National Laboratory, March 5. Polzin, S. 2008. Energy Crisis Solved! Urban Transportation Monitor, July 11. Richardson, H., and C. Bae (eds). 2008. Road Congestion Pricing in Europe: Implications for the United States. Edward Elgar, Cheltenham, United Kingdom, and Northampton, Mass. Schipper, L., C. Marie-Lilliu, and R. Gorham. 2000. Flexing the Link Between Transport and Greenhouse Gas Emissions: A Path for the World Bank. International Energy Agency, Paris. http://www.iea.org/textbase/nppdf/free/2000/flex2000.pdf. Accessed Sept. 21, 2009. Schweitzer, L., and B. Taylor. 2008. Just Pricing: The Distributional Effects of Congestion Pricing and Sales Taxes. Transportation, Vol. 35, No. 6, pp. 797–812. Small, K., and K. Van Dender. 2007. Fuel Efficiency and Motor Vehicle Travel: The Declining Rebound Effect. Energy Journal, Vol. 28, No. 1. TRB. 1996. Special Report 246: Paying Our Way: Estimating Marginal Social Costs of Freight Transportation. National Research Council, Washington, D.C. TRB. 2007. Special Report 288: Metropolitan Travel Forecasting: Current Practice and Future Direction. National Academies, Washington, D.C. TRB. 2009. Special Report 298: Driving and the Built Environment: The Effects of Compact Development on Motorized Travel, Energy Use, and CO2 Emissions. National Academies, Washington, D.C. U.S. Census Bureau. 2009. Statistical Abstract of the United States 2009. http://www.census.gov/compendia/statab/tables/09s0003.xls. Accessed April 10, 2009. Winebrake, J., J. Corbett, S. Hawker, and K. Korfmacher. Forthcoming. Development and Application of a Great Lakes Geographic Intermodal Freight Transport Model.
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