Book excerpt: This title includes a number of Open Access chapters. This new book takes a nuanced look at building a sustainable transportation infrastructure and provides an overview of the harmful effect of various modes of transportation on the environment. The environmental impact of transportation is significant. Transportation is a major user of energy, it burns most of the world's petroleum, and is the fastest-growing contributor to carbon dioxide emissions. Although environmental regulations in many countries have reduced the individual vehicle's emissions, this has been offset by an increase in vehicles on the road and airways.