This synthesis report will be of interest to officials of municipal, regional, and statewide transportation and law enforcement agencies who are responsible for roadway incident diversion practices. It will also be of interest to others who interact with these agencies to achieve a better understanding of the processes, barriers, and technologies associated with alternate route plan development and deployment. This report presents state-of-the-practice information about the development and implementation of roadway incident diversion practices. It documents specific trends in the practice, and in examining individual practices, identifies unique plans, processes, and technologies from which other agencies may find useful applications. This TRB report addresses a broad list of topics associated with roadway incident diversion and profiles successful incident diversion practices, as reported by surveyed agencies. In particular, it focuses concern on alternate route plans for random incidents, those resulting in nonrecurring congestion.