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a. Many questions remain about how transformational technologies will affect travel behavior in the short term. How much will consumers value new products and services and how much will they be willing to pay for their safety, energy saving, and emission reduction attributes? How will these technologies affect the number of trips, modal preferences, and willingness to pool rides?21 b. Consumer response to services offering automated vehicles with low operating costs could reduce the need for automobile ownership, and thereby, among other effects, free up space for urban redevelopment as such a large share of urban space is devoted to parking.22 How might transformational technologies affect auto ownership? Will the other attributes of auto ownership (flexibility, independence, status) continue to outweigh the cost advantages of using other modes? If auto ownership does diminish, how might requirements for parking diminish and what opportunities exist to repurpose on- and off- street parking for other uses? c. Over the long term, transformational transportation technologies may affect where people and businesses choose to locate, in turn affecting consumption of space, demand for infrastructure, energy consumption, and emissions.23 Will transformational technologies encourage more or less low-density residential and commercial location? d. In response to some vehicle technologies introduced to enhance safety, human beings apparently drive in ways that can negate some of their benefits; in the case of antilock brakes, for example, long-term evidence indicates no reduction in fatal crashes.24 During the long transition period of simultaneous operation of conventional and semiautomated and automated vehicles, how will drivers adapt to the safety features of semiautomated safety technologies? How will drivers of conventional vehicles respond to CAVs that may operate more slowly and cautiously? e. The general public judges risks and behaves accordingly differently than experts do for a wide variety of reasons, such as the perceived degree of control, voluntary exposure to risk, and familiarity.25 Society implicitly recognizes public perceptions by requiring far less risk from flying on a commercial flight than driving on a rural highway. What level of risk will the public require of automated vehicles? How much safer will they have to be than conventional vehicles to gain public acceptance? Serving a Growing and Shifting Population Future population growth in the United States is expected to average about 1 percent annually, with increases in highway vehicle miles of travel of similar magnitude,26 but past trends imply that this growth will not be even across the country. Included among these trends are population growth in several megaregions;27 regional migration, particularly toward the Southeast, Mountain West, and West Coast; and population declines in rural areas across the country.28 (More recent counter trends to growing urbanization in the largest metro areas may suggest rebounding population growth in medium size and smaller cities.29) trb | transportation research board8
Regardless of where it is located, low-density residential development at the periphery of existing development continues to grow the fastest.30 Many future demographic changes (internal migration, aging population, immigration, and household size) will influence the demand for transportation. Yet, where people choose to settle explains much about the modes they will rely on and the volume of future travel. These residential settlement patterns, combined with the commercial development that tends to follow, have broad implications for infrastructure demand, travel time, and the environment.31 As the largest population cohorts, the preferences of the Baby Boom and Millennial generations will have outsized impacts on future travel demand. 6. Megaregions are emerging as the engines of the national economy.32 The concentration of growth into these regions is also resulting in the worst traffic congestion,33 which continues to grow faster than capacity can be provided. Much of the traffic growth in megaregions occurs between urban cores, and most of these trips are by automobile.34 Long- distance passenger and freight movements, concentrated in corridors connecting the megaregions and the facilities that generate these trips, are facing more and more congestion. Solving megaregion transportation problems that involve both internal and external connectivity will be important in ensuring their continued vibrancy and contribution to the national economy. What are the most cost-effective transportation policies for improving internal megaregion travel and ensuring that megaregions are well connected to the rest of the nation and the world? 7. Although large metropolitan areas continue to have the highest population growth rates, growth in small metropolitan areas and nonmetropolitan counties is rebounding from losses during the Great Recession, and growth rates in these small metro areas may once again exceed those of large metro areas.35 What are the implications for local and intercity travel demand and infrastructure investments and operations if these trends persist? Regardless of the region of the country, the dominant share of residential development is occurring in suburbs and exurbs that are expensive to serve using traditional public transportation operations, which have important implications such as growing demand for road capacity and increasing auto emissions. What transportation policies and programs are most cost effective in mitigating the congestion and environmental costs of automobile trips in these settings? What role can new transportation services such as TNCs play in these areas? What role can land use policies play in shaping future development and transportation demand? 8. If the rural population shifts previously described persist, they could have broad implications for the transportation policies and programs needed to serve these distinct areas of the country. critical issues in transportation 2019 9