Work Zone Impact Assessment Methods and Applications

Two work zone impact assessment methods were developed and their applicability was illustrated using recent construction projects and actual data from the I-35 Central Texas corridor. The first method was developed for post-event analyses of the impacts of freeway construction activities, incidents and special events. The impacts have been evaluated in terms of travel times and delays. An interval estimate for maximum queue length was also provided. Delays and queues were estimated from travel time and speed data obtained by Bluetooth address matching. The method also can, and has been, used for determining work zone mobility performance measures, verifying the suitability of deployed queue warning systems, and providing feedback for future deployment decisions. Based on more than 3 years’ experience with the analysis of impacts from numerous road construction and maintenance projects as well as some major incidents and special events on the I-35 corridor, the Bluetooth-based post-event closure analysis method has proven to be a very cost-effective tool. The second method was developed for determining the best closure schedule/start time for planned work zone lane closures. The best closure start time is the one that is expected to create the shortest queue lengths, and thus have the least negative impact on travelers. The required input includes historical traffic volumes at a point upstream of the planned lane closure and the estimated work zone capacity. The work zone capacity can vary over the duration of the work zone. The method runs input-output analysis in a dual-loop framework to analyze the impact of all available closure schedule scenarios, and selects the best closure start time with the shortest expected queues.