Traffic incidents are the primary cause of delay in urban settings, reducing capacity and creating risks for both motorists and incident response personnel.As incident duration increases, the risk of secondary incidents or crashes also becomes a problem.In response to these issues, many communities have initiated incident management programs aimed at detecting, responding to, and clearing incidents in order to restore freeways to full capacity as quickly and safely as possible.This study involved the development of fully parametric hazard duration models to examine those factors impacting the time required by the Michigan Department of Transportation’s Freeway Courtesy Patrol to clear incidents that occurred on the freeway network in metropolitan Detroit.These models were developed using traffic flow data, roadway geometry information, and an extensive incident database.Four fully parametric hazard duration models are developed, each assuming a different underlying probability distribution for the hazard function.In general, each modeling framework provided similar results, though a log-logistic distribution is shown to provide a better fit for the incident clearance data in comparison to other distributions.Various factors were found to significantly affect incident clearance time, including the time of day and time of year at which the incident occurred, the geometric and traffic characteristics of the freeway segment, and the characteristics of the incident.
