Projects

Work Zone Queue Analysis Calibration/Validation Support

Project Information	Project Photos
Principal Investigator: David A. Noyce, Ph.D., P.E. - TOPS Contact Project Status: In Progress Starting Date: August 1, 2004 Ending Date: October 31, 2005 Duration: 1 year & 3 months Description: Support Data Collection and Analysis Activities to support development of Work Zone Queue Estimation Software. Rationale: Need to confirm methodology development for work zone queues.	Typical Traffic Congestion Due to Work Zones Queue Analysis - Screen Capture of WZCAT

Overview:
It is well known that lane closures due to various maintenance activities affect the capacity of roadways, and it is estimated that nearly 24 percent of non-recurrent congestion is due to work zones on freeways (U.S. Dept. of Energy, Temporary Losses of Highway Capacity and Impacts on Performance, Oak Ridge National Laboratory (ORNL/TM-2002/3). May 2002). Many highway systems that were built in the early 1970’s are approaching middle age and need a significant amount of maintenance efforts. According to a report from the U.S. DOT, an estimated 3,110 work zones were present on the National Highway System (NHS) during the peak summer roadwork season of 2001 ( U.S. Dept. of Transportation, Federal Highway Administration, A Snapshot of Peak Summer Work Zone Activity Reported on State Road Closure and Construction Websites. Washington, D.C., August 2002).

Each year in Wisconsin, many work zones activities take place during the key travel times of the day and many delays have been observed due to those activities. Considering the fact that some level of delay in a work zone is unavoidable, developing a method to estimate the delay becomes very critical. Reliable estimation of the delay due to work zone will help to accommodate traffic more efficiently and minimize any discomfort for drivers by planning work phasing and detour routes. To conduct the delay estimation in an effective and efficient manner, the method should be relatively simple and straightforward. The Wisconsin Department of Transportation (WisDOT) developed a program called “WZCAT (Work Zone Capacity Analysis Tool)” designed as a tool to help predict delays and queues associated with short-term (daily) lane closures. The purpose of this study was to validate WZCAT with field data collected from Wisconsin work zone operations in 2004.

Traffic flow data was acquired from loop detector locations within and near the work zones. All closures included in the analysis were videotaped with MONITOR cameras to determine actual start and stop times of the work zone and to determine traffic flow capacity through the work zone. The corresponding length of queue was measured manually thorough visual/videotape evaluation. Between September 2004 and November 2004, a total of six closures were videotaped, four of which are presented in this summary.

As an initial step, basic algorithm of the WZCAT has been analyzed. It calculates the difference between capacity and demand in time t. If demand is greater than given capacity, then the difference becomes queued vehicles. Thus, performance of the WZCAT is very sensitive to the value of several key variables including “work zone capacity”, “demand when work zone is in place”, and time. Validation of those figures which are embedded in WZCAT is being conducted.

Summary of Data Collection:

Date	Location	Closure	Video	Traffic Volume Data Non-WZ Day	Traffic Volume Data WZ Day	Sitemap
09/11/2004	1-894/US45 NB @ Greenfield Ave.	3 lanes reduced to 1 lane	v	v	v	V
10/04/2004	1-94 NB @ College Ave.	Left Lane (3 lanes reduced to 2 lanes)	v	v	v	V
11/02/2004	US45/21 NB @ Pilgrim Rd.	2 Right Lanes (3 lanes reduced to 1 lane)	v	v	v	V
11/04/2004	US45/21 NB @ Pilgrim Rd.	2 Right Lanes (3 lanes reduced to 1 lane)	V	v	v	v

Three of the study cases consist of single lane closures of three lanes to two lanes. Similarly, the final study case is a three lane to one lane closure. All closures started between 7 and 8 AM and continued until around mid-afternoon. This study will validate the performance of the WZCAT in various aspects including the efficiency and effectiveness to practitioners.

Finally, the review of recent studies and practices is being done to identify the functional needs and important variables to characterize work zones such as “lane width”, “intensity of work zone”, “latitudinal clearance”, and others. The final report will include all findings from four case studies and recommendations.

Documents:

Document Name	Files	Date Posted