Mega-cities are urban areas with more than 10 million residents. In 2011, 23 urban areas qualified as megacities: 13 in Asia, four in Latin America, and two each in Africa, Europe and North America. By 2025, when the number of mega-cities is expected to reach 27, Asia will have gained another nine, Latin America two, and one each in Africa, Europe and North America.1 Mega-cities experience a wide range of social and environmental problems, many of them related to mobility.
All of the mega-trends we have identified, as well as other challenges to sustainable mobility, are at their worst in mega-cities, and engender paralyzing traffic congestion, air pollution, vehicle-related injuries and fatalities, and health problems. Furthermore, social inequality and the dislocation of families and communities are increasing as people move from rural areas to mega-cities seeking economic opportunities. To develop mega-city mobility strategies will require addressing the mobility needs of rural as well as urban residents, as many mega-city problems could be improved by developing new approaches to the transportation of people and goods between rural and urban areas, and by reducing the need for rural–urban migration.
New mobility solutions depend on collaboration and partnership. Technology can “connect the dots,” but only humans can get the varied institutions and interests involved in urban and rural mobility to work toward a common end. Projects like those described in this section require extensive stakeholder engagement and establishment of trust between the many partners with a role to play.