AASHTO RSDG-4, Roadside Design Guide, 4th Edition (2011), presents a synthesis of current information and operating practices related to roadside safety. Chapter 1 introduces roadside safety and Chapter 2 covers economic evaluation of roadside safety treatments. Chapters 3 and 4 address roadside topography and drainage features and the treatment of sign, signal, and luminaire supports, utility poles, and trees. Remaining chapters cover roadside barriers, median barriers, bridge railings and transitions, end treatments, and traffic barriers, traffic control devices, and other safety appurtenances. The guide also treats roadside safety in urban or restricted environments, erecting mailboxes on streets and highways, and roadside safety on low-volume roads and streets. Highway agencies can use the guide as a resource document from which to develop their own standards and policies.