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a. How can rural and farm access to services and markets be sustained as populations and resources for infrastructure decline and if competition among freight carriers for transporting goods decreases? As populations and tax bases decline, how will rural highway routes be funded? b. Access is a particular challenge for the economically disadvantaged, the elderly, and the disabled, who lack transit options and service by TNCs due to low population densities and an absence of high-speed Internet service in many rural areas. How can rural populations be ensured adequate access to jobs and services? How is that access changing? Which policies are needed to provide adequate rural access? 9. Although many Millennials, the largest population cohort, are living in center cities, the largest portion are settling in the urban periphery or in areas between urban centers within megaregions,36 making it more difficult to provide nonautomobile options. Most Baby Boomers continue to prefer single-family homes in the suburbs (about two-thirds) or in rural areas (more than one-quarter).37 What are the transportation implications of these trends among the largest population cohorts? How can adverse environmental effects from transportation be minimized? Energy and Sustainability Drastic reductions in greenhouse gas (GHG) emissions are needed in the coming decades from all sectors to avoid the possibility of catastrophic climate change.38 Transportation now accounts for the largest share (28.5%) of U.S. GHG emissions.39 Moreover, other sectors are reducing carbon emissions much faster than transportation.40 Transportation may be the most challenging sector to address because of its requirements for high-energy density fuels, particularly for aviation, large ships, and long-haul trucking. Largely for this reason, even if and when the nation confronts transportationâs role in climate change, oil and natural gas will continue to be major sources of transportation energy in the United States and internationally for many years to come. Adverse environmental effects result not only from producing, shipping, and combusting energy, but also from mining and manufacturing the many components of vehicles, including the materials needed for rechargeable batteries.41 (The public health consequences of vehicle emissions are discussed in the Safety and Public Health section of this report.) Critical questions in moving toward sustainability include determining the most cost-effective strategies for reducing GHG emissions; accounting for the full environmental consequences of mining, producing, and consuming transportation fuels and vehicle and battery components; deciding on the appropriate public- and private-sector roles in facilitating and achieving the conversion to both battery and hydrogen powered electric-drive vehicles; and building public and political support for implementing the most effective strategies. Research challenges include addressing a transition to low-GHG energy sources for transportation that is more driven by public good than private benefits, uncertainty about both future technologies and their economics, and consumer willingness to pay for energy efficiency, among other topics. 10. Transportation in the United States generates more GHG emissions than any other sector and its share is growing, largely due to fossil fuel consumption.42 To make a proportional contribution to reducing GHGs, however, reductions from transportation would need to go beyond the aggressive federal fuel economy and GHG standards adopted in 2012 (which themselves are being reconsidered as too trb | transportation research board10
aggressive at the time of this writing).43 What are the most cost-effective strategies to stabilize and ultimately reduce GHG emissions? What is the role of transportation in achieving this goal?44 Other key challenges include reliably monitoring and confirming progress toward GHG reduction goals; the potential for publicâ private collaboration in achieving reduction goals; the respective sectoral roles in increasing energy efficiency and reducing carbon intensity, reducing motorized travel, and improving system efficiency; identifying the necessary policy actions and technological advances; and managing the transition to automated vehicles to reduce GHGs rather than increase them.45 11. The price of transportation fuel and motor fuel taxes and other transportation fees do not reflect the social and environmental costs that transportation imposes. Hence, society cannot depend on market forces alone to identify and apply environmentally sustainable energy sources for motor vehicles, aircraft, and vessels in the coming decades. What are the most consequential and cost-effective public policy strategies to move the transportation sector toward sustainable energy sources while taking into account the full environmental consequences from the energy source through consumption, emissions, and recycling of spent vehicles and components? 12. As major industrialized nations impose zero- and low-emission requirements, automakers are responding with promises to shift to the production of electric, plug-in hybrid, and hydrogen fuel cell vehicles, which raises questions about the public role in encouraging electrification of the fleet and the impact that growing electricity demand will have on the energy grid and overall emissions. a. How can public policy influence consumer acceptance of electric vehicles?46 What is the appropriate public role in facilitating the distribution and adequate coverage of hydrogen and battery refueling and recharging infrastructure? What policies will work and be most cost effective? b. What are the implications of the growing reliance on electrical power in transportation and how can electrification be managed to gain the most societal benefit? i. Using electricity to power transportation vehicles could reduce GHG emissions, but the scale of the benefits depends on the source of energy (coal, gas, petroleum, nuclear, renewables)47 that electric utilities choose or are incentivized to employ. How can the public sector best affect these choices? ii. What will be the impact of growing demand from transportation on the electric grid? How can utilities and public agencies, as needed, encourage the timing of recharging to maximize benefits for the grid and users?48 c. What is the potential for transportation infrastructure itself to generate energy from solar radiation, wind, or other environmentally sound sources? 13. Sustainability requires that there be long- term consideration of the implications of decisions and policies on social, economic, and environmental systems. Examples include making decisions based on life-cycle cost considerations and the long-term vitality of communities and key natural environmental systems. How can consideration of long-term sustainability goals be better incorporated into public policy debates and decisions about transportation? critical issues in transportation 2019 11
