Using operational sequence diagrams to assess interagency coordination in traffic incident management

One role of state-level Departments of Transportation (DOT) is traffic incident management (TIM): managing incidents that hinder traffic flow on interstate highways and requiring responses from multiple agencies (e.g., police, fire). This article reports on a portion of a larger study investigating how DOTs collect and analyze basic TIM performance measures (e.g., lane clearance times). Since evaluation of interagency coordination is one area of TIM in which little success has been attained (FHWA, 2003), process-based benchmarking methods borrowed from operations management may be useful tools. One such tool, operational sequence diagramming, was used to show how tasks and resources were allocated between the different agencies responding to a particular type of traffic incident: a disabled vehicle (no injuries or property damage). In this case, up to three agencies (state police, transportation, and towing/recovery) might interact to coordinate the safe removal of the vehicle and restore normal traffic tlow. Completing these events required agency persom1el to perform specific functions in specific sequences, something that did not occur consistently or following recommended guidelines. The OSDs illustrated how differences in response operations could be identified and aid decision makers in TIM in evaluating possible options to reduce variability in response protocols and, ultimately, traffic delays.