This book examines causes and deterrents of transportation accidents by mode--automobiles, truck, air, recreational boating, commercial vessels and railroads--with the focus on accidents in the U.S. The examination enhances our understanding for developing effective multimodal public policies for improving transportation safety. The discussion reveals that the primary cause of accidents in one mode may not be the primary cause in another mode and equally that an effective deterrent for improving safety in one mode may not be an effective deterrent for another mode. The book will be of interest to policy makers and investigators of transportation safety. The book consists of nine chapters. Following the Introduction chapter, possible causes of highway accidents--driver, vehicle, and highway characteristics--are examined in Chapter 2 along with economic and environmental factors. Chapter 3 then discusses the effectiveness of various deterrent policies--motor vehicle inspection, the minimum legal drinking age, the speed limit, and seat belt laws--for auto accidents, as well as the effects of vehicle speed and speed variance on these accidents. This is followed by a discussion of causes and deterrents of truck accidents in Chapter 4. Chapter 5 considers air accidents, discussing the role of economic deregulation and type of air carrier. Chapter 6 addresses recreational boating accidents, with particular attention given to alcohol involvement in these accidents. Chapter 7 examines commercial vessel accidents with a discussion of safety standards and enforcement. Chapter 8 considers rail accidents, with particular attention given to the effects of deregulation. The final chapter summarizes lessons learned from the previous chapters for improving transportation safety across modes, i.e., for reducing transportation accidents, accident risk, and accident severity.