It is a commonly quoted fact that the world has become primarily urban, with more than 50% of the population living in cities for the first time in history. The United Nations (2016) estimates that seven out of ten urban residents in the world reside in cities in the Global South1, a number expected to continue to rise. Cities in the Global South have been expanding rapidly in recent decades, accounting for the majority of global urban growth. This growth is often chaotic and unplanned — frequently in neighborhoods built by residents themselves — and as a result, gaps in water, civic, sanitary, transportation, education, and other infrastructure are common (UN, 2016). Additional factors typically complicate adequate urban planning and development, including relatively weak institutions, high levels of poverty and inequality, a large informal economy, and a chronic lack of resources.
As a result, urban residents in these regions often suffer from a myriad of problems that negatively impact their quality of life and prosperity, such as air and water pollution, growing congestion and unbearable commutes, high levels of crime, social and economic spatial segregation, limited housing options, and relatively high costs for public services. These issues reach critical levels in the world’s so-called “megacities,” defined as urban areas with a population of more than 10 million people (UN-Habitat, 2016). Most of the world’s current and future megacities are and will be in countries of the Global South (UN-Habitat, 2016). In cities like Sao Paulo (Brazil), Delhi (India), Lagos (Nigeria), Jakarta (Indonesia), and Mexico City (Mexico), collectively home to hundreds of millions of people, crucial systems like public transportation and water supply are pressed to the limit on a regular basis. Climate change will almost certainly pose additional pressures, in the form of extreme weather events, like floods and droughts. (UN-Habitat, 2016)
Most megacities of the Global South have followed increasingly car-oriented development patterns, despite the fact that most residents still depend heavily on public transport. These trends exacerbate environmental and social consequences, inducing sprawl and increasing reliance on the automobile. The effects of these trends are amplified by a lack of adequate public housing solutions that often pushes lower income populations to the peripheries of urban areas. Residents in these areas, far from jobs and mass transit, are forced to suffer long and expensive commutes, often requiring several transfers between different travel modes to access jobs in the city centers (Guerra, 2017).
In this context, improving public transit has emerged as a principal challenge to increasing accessibility and quality of life for millions of low and middle income residents (Guerra, 2017). Wise investments in public transportation can increase cities’ economic competitiveness, energy efficiency, and equity, while avoiding the negative externalities like noise and air-pollution that are associated with excessive automobile use (Suzuki et al. 2013).
1 The “Global South” is a term used to refer to less-developed countries. Despite problems with a geographic definition for such differences, academics and policy makers consider it preferable to other terms like “Third World” or “Developing World” (Hollington, 2015).