All phases of road developmentâ€"from construction and use by vehicles to maintenanceâ€"affect physical and chemical soil conditions, water flow, and air and water quality, as well as plants and animals. Roads and traffic can alter wildlife habitat, cause vehicle-related mortality, impede animal migration, and disperse nonnative pest species of plants and animals. Integrating environmental considerations into all phases of transportation is an important, evolving process. The increasing awareness of environmental issues has made road development more complex and controversial. Over the past two decades, the Federal Highway Administration and state transportation agencies have increasingly recognized the importance of the effects of transportation on the natural environment. This report provides guidance on ways to reconcile the different goals of road development and environmental conservation. It identifies the ecological effects of roads that can be evaluated in the planning, design, construction, and maintenance of roads and offers several recommendations to help better understand and manage ecological impacts of paved roads.

In Divided Highways, Tom Lewis tells the monumental story of the largest engineered structure ever built: the Interstate Highway System. Here is one of the great untold tales of American enterprise, recounted entirely through the stories of the human beings who thought up, mapped out, poured, paved - and tried to stop - the Interstates. Conceived and spearheaded by Thomas "the Chief" MacDonald, the iron-willed bureaucrat from the muddy farmlands of Iowa who rose to unrivaled power, the highway system was propelled forward through the pathbreaking efforts of brilliant engineers, argued over by politicians of every ideological and moral stripe, reviled by the citizens whose lives it devastated, and lauded as the greatest public works project in U.S. history.