A certain amount of delay in work zones is typically assumed to be unavoidable, often considered a cost of doing business when making roadway improvements. As such, developing a method to predict delay, such that appropriate countermeasures to minimize this delay can be implemented, is critical to successful work zone management. Predicting work zone delay in an effective and efficient manner should not require extensive data collection or long and complex coding efforts. In other words, the procedure should be customizable for local data availability, easy to use, and allowable for straightforward interpretation by practitioners. To this end, WZCAT (Work Zone Capacity Analysis Tool) analytical software program was developed as a tool to predict delays and queues for short-term (daily) work zone closures. WZCAT bases its queue-length predictions on a simple input/output model, with the capacity of the work zone controlling the throughput. The purpose of this study was to evaluate and enhance WZCAT with field data as well as summarize various aspects of traffic flow and queuing patterns during work zone operations on selected urban freeways. According to the field observation, significant traffic volume changes on exit/entrance terminals upstream of work zones and the stabilization of vehicle queue after initial queue development were found. A Demand Adjust Factor (DAF) developed and applied to WZCAT-R to include this in an effective and efficient manner. WZCAT-R produces effective results for queue prediction, and can be an effective and reliable tool in prediction of work zone delay and queue development and help engineers proactively plan work phasing, lane restrictions, and potential detour routes in an effort to move traffic more efficiently.
Samenvatting