Whether you are a student considering a career in civil engineering and transportation planning, a public official interested in the future of infrastructure, or a person who simply cares about bridges, this book offers an accessible and illustrated introduction to the most beloved feature of our built environment. Learn about engineering basics: the forces that bridges must resist to stay aloft and the principles by which engineers decide which types of bridges make sense at which sites. Find out how engineers protect bridges from their greatest threats--the earthquakes, floods, and other hazards that can cause catastrophic damage. Moving from engineering to planning, learn how we decide whether a bridge is worth building in the first place, learn about controversial features of cost-benefit analysis, and about the transportation models by which planners forecast bridge effects on traffic patterns. Investigate a sometimes intractable problem: why a project often creeps along for a decade or more to get from initial studies to the day the ribbon is cut, undergoing vast cost escalations. Also explore the environmental impact of bridges, and the meaning of a "sustainable bridge," and whether bridges could once again be built, like ancient Roman ones, to last a thousand years.