This workshop was held June 11 and 12, 1998, at the U.S. Department of Transportation (DOT) John A. Volpe National Transportation Systems Center in Cambridge, Massachusetts. Participants included DOT staff and consultants, state highway and rail representatives, railroads, railroad suppliers, and research and development organizations. The workshop aimed to gather practitioner input regarding requirements and constraints for intruder and obstacle detection on rail rights-of-way (ROW) and grade crossings, identify institutional and implementation considerations, and develop a consensus for a high level functional concept for such a detection system. Objectives were achieved through sessions designed to review the operational, technical, and regulatory issues; hear the concerns, priorities, and ideas of all participants; and formulate a consensus statement to guide the next steps. IODS will integrate systems that sense hazards; detect threats by assessing sensory data; transmit alarms and supporting data to decision/control points; and collect and display event data for analysis and action. The technologies will be applied to meet the varied requirements of rail grade crossings, ROW, and railroad facilities. The technology requirements will be consistent with Intelligent Transportation Systems architecture.