When alternative incident management strategies areevaluated, there is often a need to convert reductions in incident clearancetime to a monetary cost saving.  In thepast, the Virginia Department of Transportation (VDOT) has used unit delaycosts from other agencies to estimate incident congestion costs and the benefitof incident management programs.  Toimprove current practices, congestion cost values developed specifically forVirginia conditions are desired.

This study developed a method toproduce planning-level incident congestion cost estimates for interstatehighways in Virginia.  The per-minuteincident congestion costs were estimated using economic, traffic, incident, androadway data from multiple sources and analyzed at different spatial andtemporal aggregation levels.  The resultsshowed that the proposed method can produce reasonable estimates of congestioncost at a planning level.  The incidentcongestion costs vary across VDOT districts, routes, time-of-day, andday-of-week; the costs can vary from less than $1 per incident-minute forshoulder-closed incidents in the Bristol District during off-peak hours to$1,347 per minute for lane-blocking incidents in the Northern Virginia Districtduring AM peak hours. 

With the variation in costs, thestudy recommends that corridor-based cost values (where “corridor” is definedas a directional route within a district) be used for analyses of projectsacross different locations and time periods. The study also recommends that VDOT develop a plan to maintain and updatecongestion cost values and develop a field-ready App to provide easy access tothe congestion cost values for VDOT staff.