Measuring the Impacts of Incidents, Workzones, and Weather Events on Virginia Freeways
Measuring system performance is essential for continual improvement of roadway operations. To realize such benefits, and to take advantage of the increased availability of travel time data on Virginia roadways in recent years, VDOT initiated a pilot study in the current Business Plan.
The study identified ways in which travel time data can be used to support and enhance the operational decisions at the district level. In specific, the study analyzed the mobility impacts of two incidents, two work zones, and two weather events in detail. Recent incidents, work zones, and weather events in Virginia with varied characteristics (geographical area, rural/urban, day of week, time of day, type of event etc.), and with significant impacts on one or more interstates were first identified. The study identified several specific performance measures such as delays, costs, queue lengths and durations, impacted volume, speed reductions etc. Several visualizations were also developed or applied, for better understanding these measures and events. The most appropriate set of graphical visual aids for the event type was chosen and then the event-specific performance measures were applied. The results were summarized in a table and, for metrics where this was applicable, more detailed charts, plots, graphs, or maps were presented. All these findings were assembled in individual event reports which concluded with a lessons learned section. T
wo main data sources were used in the study– commercially available travel times, and traffic volumes from continuous count stations. Several lessons were learned in the process, from benchmark selection approaches, to data availability, data quality, and calculation methodologies.