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Environmental Assessment of Air and High-Speed Rail Corridors (2013)

Chapter: Chapter Eight - Conclusions

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Suggested Citation:"Chapter Eight - Conclusions ." National Academies of Sciences, Engineering, and Medicine. 2013. Environmental Assessment of Air and High-Speed Rail Corridors. Washington, DC: The National Academies Press. doi: 10.17226/22520.
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Page 29
Page 30
Suggested Citation:"Chapter Eight - Conclusions ." National Academies of Sciences, Engineering, and Medicine. 2013. Environmental Assessment of Air and High-Speed Rail Corridors. Washington, DC: The National Academies Press. doi: 10.17226/22520.
×
Page 30
Page 31
Suggested Citation:"Chapter Eight - Conclusions ." National Academies of Sciences, Engineering, and Medicine. 2013. Environmental Assessment of Air and High-Speed Rail Corridors. Washington, DC: The National Academies Press. doi: 10.17226/22520.
×
Page 31

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29 chapter eight CONCLUSIONS There is significant experience and research on the competi- tion and complementarity of air and high-speed rail (HSR) modes. The existing research covers areas including sys- tem structure (vehicle technology, cost, ridership, etc.) and environmental effects. The objective of this synthesis is to bring together research and other findings related to air and HSR environmental assessments. A literature review is the primary tool for collecting data for this synthesis of current practice. The literature revealed that there are two approaches to categorizing air and HSR assessments: attributional and consequential. Attributional assessments look backward from some point in time and are used to allocate the environ- mental effects to passenger travel, a trip, or vehicle travel. Consequential assessments look forward as a result of a sys- tem change and can be used to determine the changes to the total regional environmental effects caused by a particular decision. The air and HSR modes, although sometimes overlap- ping, are fundamentally structured differently. The aviation system is structured as a system of nodes (i.e., airports) con- nected with aircraft operated by independent operators. The spatial scale of the nodes is vast, such that passengers can travel between nodes in a region or in two separate countries. In contrast, the HSR system is structured as a system of links, with the spatial scale being limited to a fixed regional area and one operator providing both the rail infrastructure and locomotive services. HSR is planned in designations termed corridors: rail track between major cities and the regions between. In contrast, aviation is not planned in corridors. Airports are planned to serve a region, and airlines connect this region to their hub airports and possibly some additional airports. That these two networks may have some overlap- ping portions yet serve different scales of network presents a complexity when defining the system structure for an envi- ronmental assessment. The result is spatial incompatibility between modes; rail service is planned in corridors, whereas air service is planned over a national and global network. Spatial incompatibility across modes makes it difficult to compare environmental assessments. Some studies consider air and HSR to be “competitive corridors,” whereas others view the broader aviation system network and HSR services to be complementary when nearby regions are linked with an airport. The fundamental differences in air and HSR envi- ronmental assessments impede the drawing of the analytical system boundary for environmental assessments; aviation is a system of nodes with the planning focused on airports, and rail is a series of nodes connected by links with the planning focused on specific corridors. The focus when synthesizing the literature was on two types of literature: government-driven environmental impact assessments and academic literature. Government-driven environmental impact assessments are in the form of National Environmental Policy Act (NEPA) studies. In gen- eral, the NEPA process investigates and reports the extent of the environmental impacts of the proposed federal action and further evaluates the environmental impacts of feasible and prudent alternatives to the proposed action. When envi- ronmental impacts are deemed to be potentially significant, an Environmental Impact Statement (EIS) is prepared in accordance with the NEPA process to document the extent of the environmental impacts. Alternatives that are deemed feasible and prudent move forward for full environmental impact review. For an alternative mode to be fully assessed in an environ- mental review process, it must meet the purpose and need. The Purpose and Need Statement in the EIS is intended to define the objectives to be achieved by the proposed project (purpose) and the overarching problems that motivated the project (need). The framing of the purpose and need is a pri- mary factor in determining the feasibility of alternatives in an EIS. All EISs must include a discussion of the purpose and need for the action, a description of the proposed action and alternatives to the proposed action, analysis of the affected environment and environmental consequences, and mitiga- tion measures. However, considering the spatial incompat- ibility of the two modes, assessing if HSR meets the needs of an aviation project, and vice versa, is a highly complex pro- cess. As a result, few detailed modal assessments are found in EIS documents. Government-driven work provides an important frame- work for assessing air and HSR environmental compari- sons, yet the language of NEPA alternative assessments can preclude a full, detailed analysis of modal alternatives. Government-driven work also notes the role HSR can play as a feeder and as a competitor; however, owing to other complications to be explored, few detailed assessments have been performed.

30 corridor (Janic 2003). Furthermore, it is important that growth-inducing impacts on surrounding land be con- sidered. Both air and HSR systems have the potential to create indirect land use impacts through new residen- tial, commercial, and industrial activities near airports and train stations. • Givoni’s (2007) attributional assessment found that between London and Paris the CO2 emissions from HSR travel are 7.2 kg/seat and from air travel are 44 kg/seat. • Janic’s (2003) attributional assessment estimated that the French HSR service (the TGV) emits 4 g CO2 per passenger-kilometer traveled (89% nuclear electric- ity), the German HSR service (the ICE) 28 g (50% coal electricity), and a competing flight between 100 and 150 g. These emissions combined with other damages (i.e., other air pollution, noise, land use, congestion, and accidents) are used to monetize the external costs of HSR and air travel, respectively, at Euros 0.002 to 0.01 and 0.02 to 0.08 per passenger-kilometer traveled in the United States and Europe. • Chester and Horvath (2012) included roughly 150 life-cycle components in their assessment of future long-distance travel in California and, by first using an attributional approach, found that although HSR is likely to produce lower GHG emissions per passenger-mile traveled, an average occupancy of 130 to 280 passengers is needed to compete with emerging aircraft and one of 80 to 180 passengers to compete with a 35-mpg sedan. Chester and Horvath then developed a consequential assessment to determine that, given future HSR adoption uncertainty, greenhouse gas (GHG) payback will occur between 20 and 40 years, which includes emissions from construction and maintenance activities. They included modeling of emerging technologies, regional flight char- acteristics (instead of multiplying a per seat-mile factor across forecasted seat-miles), and uncertainty in mode shifting. • Givoni (2007) computed the environmental benefits of mode substitution for air and HSR by estimating the aircraft, access/egress, aircraft journey, and HSR jour- ney air pollution externalities per seat between London and Paris. He found that the external costs of travel on HSR are 0.52 Euros per seat and on air are 1.03 Euros per seat. Janic (2003) monetized air emission externali- ties and estimated that the marginal costs of HSR travel generally are lower than those for air travel in Europe, but Janic did not assess the total costs of each system. In investigating the role of air and HSR as competitors and complementary modes, understanding ridership is a cru- cial component. Several studies cite the importance of accu- rate ridership forecasts to understand the environmental outcomes of future long-distance transport systems. Some studies explore the sensitivity of environmental performance to ridership. Other studies focus on understanding the long- run per passenger-mile traveled footprint of passengers to understand the environmental intensity of service. Per-trip Although there is a growing body of academic literature that seeks to reconcile spatial incompatibility, the academic literature is not bound by the same legal and institutional protocols of the environmental review process and therefore does not have to draw a constrained system boundary. Aca- demic literature is free to compare any modes, regardless of whether they are implemented, programmed, or conceptual. The following is a sample of results from academic literature: • The substitution of air by HSR was found to reduce NOx, CO, hydrocarbon (HC), and PM10 emissions but increase SO2 by a factor of 12 owing to the sulfur con- tent of primary fuels for electricity generation (Givoni 2007). Givoni’s (2007) attributional assessment found that between Paris and London there were significant reductions in criteria air pollutants (CAP) between air and HSR, respectively (18 to 0.4 g/seat HC, 126 to 2.2 g/seat CO, 71 to 18 g/seat NOx, 2.9 to 35 g/seat SOx, and 2.0 to 1.0 g/seat PM10). • In 2004, a consequential assessment by Jamin et al. found that substituting one-third of air travel for HSR in the relevant corridors increased SOx emissions across the corridors from 100 to 2,000 tons and decreased NOx (5,000 to 4,200 tons), HC (2,200 to 1,900 tons), and CO emissions (6,100 to 4,200 tons). This could be important when assessing human health and environ- mental impacts and would depend on where the emis- sions occur. Increases in sulfur emissions may result in acidification of soil and groundwater and occur from changes in operation and propulsion energy inputs and also life-cycle effects (Chester and Horvath 2012). The study found that the time until environmental payback can vary significantly with the uncertainty in future rid- ership, which is primarily affected by the number of trip takers shifting from automobiles. • The European Commission (2002) found that people are generally more annoyed by aircraft noise than rail noise, with highway noise falling between these two modes. Eagan and Mazur (2011) noted that although this certainly has to do with acoustic factors, it also has to do with attitudes toward the noise source. • Along with their spatial incompatibilities, air and HSR can have differing noise profiles. Aircraft noise is primar- ily a concern for near-airport operations because of the occurrence of low-altitude flight. Because HSR involves a system of links between stations, HSR noise may or may not occur predominantly at the nodes because of a combination of mitigation possibilities (FRA 2005a), the population density near tracks, and operation characteris- tics. In general, there is less impact expected near stations than along the route. • Air transport typically requires less land per passenger trip than does HSR transport (Rus 2011). Airport land- take occurs when the airport sees a need for capacity expansions, whereas land use impacts from HSR are dependent on the length of HSR line and the environ- ment along the line, not the volume of traffic in the

31 tation infrastructure investments, to developing a framework to justify HSR projects, to computing the environmental ben- efits of mode substitution for air and HSR. Through the synthesis of the literature, major gaps in knowledge were found: • Methodological frameworks and tools that assess future operating characteristics of long-distance transporta- tion service have not been fully developed. Such frame- works and tools would need to address the two main components of the relationship between air and HSR: as competitors and as complementary modes. • A framework and methodology are needed to analyze the impact to airline operations, and thus airport infra- structure use, of development of HSR. The same goes for the “no build” alternative: estimating the future of aviation flows in the absence of HSR infrastructure is necessary. • By performing consequential assessments instead of attributional assessments, organizations incentivize practitioners to use comprehensive assessment frame- works. The consequential assessment would require an understanding of how up-front investments lead to regional operating effects. Although NEPA in many ways requires an assessment of impacts, the academic literature has for the most part avoided these quantifi- cations, likely because of the complexities of accurate estimates. In conclusion, environmental assessments of air and HSR systems have produced valuable knowledge for reduc- ing human health, ecosystem services, and resource deple- tion impacts. However, gaps still exist. If these gaps can be closed, decision makers would have more information on which to base their decisions. By establishing regional plan- ning processes, drawing on previously established methods, and developing new tools and information for better under- standing future processes, more comprehensive approaches can be developed to better understand the benefits of intel- ligent air and HSR planning. measures are common and valuable for eliminating the dif- ferences in trip distances to reach the same origin-destination pairs. Regardless, current air and HSR transportation sys- tems that offer lower emissions might appear attractive from an environmental standpoint, but if such a system is unable to attract passengers, it will produce negative environmental benefits: a train or an aircraft with no payload does all harm and no good. In an effort to produce unifying analytical boundaries and metrics for comparing air and HSR systems, the following assessments are used in academic literature: life-cycle assess- ment (LCA), impact assessment, benefit-cost analysis, and GHG assessment. LCAs of air and HSR systems can include vehicles (manufacturing and maintenance), infrastructure (construction, operation, and maintenance), and energy pro- duction (primary fuel feedstock extraction, processing, and distribution) components. LCA results for California’s air and HSR systems show that (1) for air, life-cycle compo- nents can increase the mode’s footprint by roughly 20%, and (2) for HSR, concrete and steel used in infrastructure con- struction may double the GHG footprint of the mode. Sig- nificant research and efforts have been made by the aviation industry and academics to understand the human health impacts of near-airport operations. Although GHG emis- sion comparisons are critically important, it is also important that future studies consider other air emissions, as well as the environmental concerns identified by NEPA. By defin- ing sustainability broadly, opportunities will exist for under- standing how the (1) reduction in one environmental concern may lead to a reduction in another, or (2) reduction in one environmental concern may lead to an increase in another; that is, an unintended trade-off. Finally, defining an HSR cost model presents a unique set of challenges compared with the aircraft cost model development. Because HSR projects are built over various topographical landscapes, different techni- cal solutions and levels of investment are needed. Although some studies have attempted to quantify the economic ben- efits of air travel, similar HSR benefits for a region have not been rigorously studied. Various studies in this area range from developing social welfare functions to assess transpor-

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TRB’s Airport Cooperative Research Program (ACRP) Synthesis 43: Environmental Assessment of Air and High-Speed Rail Corridors explores where additional research can improve the ability to assess the environmental outcomes of these two systems.

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