A replacement to the publication entitled 'Highway design and operational practices related to highway safety', also known as 'The Yellow Book', and most recently published in 1974.

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 321: Roadway Safety Tools for Local Agencies examines the safety tools and procedures that are practical and relatively easy to apply, and that can be implemented by agencies with limited financial support and personnel. Recognizing the wide variation in the operations and responsibilities of local agencies, the report acknowledges that the level of expertise in transportation safety analysis also varies greatly.

"The Roadside Design Guide presents a synthesis of current information and operating practices related to roadside safety and is written in dual units-metric and U.S. Customary. This book is a guide. It is not a standard, nor is it a design policy. It is intended to use as a resource document from which individual highway agencies can develop standards and policies. Although much of the material in the guide can be considered universal in its application, several recommendations are subjective in nature and may need modification to fit local conditions. However, it is important that significant deviations from the guide be based on operational experience and objective analysis. The 2011 edition of the AASHTO Roadside Design Guide has been updated to include hardware that has met the evaluation criteria contained in the National Cooperative Highway Research Program (NCHRP) Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features and begins to detail the most current evaluation criteria contained under the Manual for Assessing Safety Hardware, 2009 (MASH). For the most part, roadside hardware tested and accepted under older guidelines that are no longer applicable has not been excluded in this edition." -- AASHTO website.