Motorized automobility and suburban living are not only highly valued but are also associated with a range of serious social problems, including deaths and injuries of motor-vehicle users and nonusers, roadway congestion, air pollution, dependence on insecure oil supplies, community fragmentation, and climate change. However, these problems, which make the present transportation and land-use system unsustainable, are not necessary consequences of automobility and suburban living per se, but rather are attributable mainly to the high kinetic energy of fast, heavy-motor vehicles (FHVs). Therefore, the challenge in creating a sustainable transportation and land-use system is to dramatically lower the kinetic energy of personal travel while retaining the advantages of personal motorized automobility and low-density development. Our approach is to redefine the technical artifact that is the conventional automobile and create two autonomous and universally accessible travel networks at a citywide scale: one for FHVs, the other for low-speed, low-mass modes including walking, cycling, and a new class of motor vehicles. In this paper, we motivate the need for this new urban-settlement and transportation-infrastructure scheme (USATIS), describe its design principles and features, review aspects of it in the literature and in the real world, present analyses covering a wide range of sustainability criteria-safety, mobility, congestion, environmental and energy-use impacts, urban aesthetics and community fragmentation, and economics-and discuss challenges for implementation and future research. We conclude that our USATIS does have the potential to support sustainable transportation without making people drive less or give up suburban living, but that before practical implementation plans can be considered, more research needs to be done on how people will adapt to the opportunities and constraints in the proposal. [ABSTRACT FROM AUTHOR]