Work Zone Impact Assessment Methods and Applications

Two work zone impact assessment methods were developed and their applicability was illustrated with data from recent construction projects on the I-35 Central Texas corridor. The first method was developed for postevent analyses of the impacts of freeway construction activities, incidents, and special events. The impacts were evaluated in terms of travel times and delay. An interval estimate for maximum queue length was also provided. Travel times and speeds were obtained by Bluetooth address matching. The method has also been used for determining work zone mobility performance measures, verifying the suitability of queue warning systems, and providing feedback for future deployment decisions. Based on more than 3 years’ experience with the analysis of impacts of road construction and maintenance projects as well as some major incidents on the I-35 corridor, the Bluetooth-based postevent closure analysis tool has proved to be very cost-effective. The second method was developed for determining the best closure schedule and 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 has the least negative impact on travelers. The required input includes historical traffic volumes at a point upstream of the planned lane closure and 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.