Most countries have witnessed rapid urbanization and growing use of automobiles for more than half a century. This has resulted in increased urban expansion and increased demand for motorized transportation, with a variety of environmental, social, and economic effects. Urban transportation is a major source of greenhouse gas emissions and a health hazard owing to air and noise pollution. Commuters and goods transporters bear enormous economic and productivity losses as a result of traffic congestion caused by unsustainable transportation infrastructures. These issues are more acute in cities in developing countries. In the following decades, this region will account for over 90% of world population growth.