TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 89 contains the appendixes for NCHRP Research Results Digest (RRD) 306: Identification of Liability-Related Impediments to Sharing §409 Safety Data among Transportation Agencies and a Synthesis of Best Practices. RRD 306 examines liability risks associated with sharing safety data among transportation agencies pursuant to Section 409 of Title 23, U.S.C. RRD 306 also explores best practices; reviews the Pierce County, Washington v. Guillen decision and its potential impact on managing state liability risk; and describes potential strategies for overcoming the impediments to data sharing, specifically those related to liability.