Work Zone Capacity Estimation for High Truck Volume Routes in Arkansas Predicting Highway Capacity through Work Zones with High Truck Volumes and Reduced Lane Geometry Based Upon Local Conditions

Work zones on freeways are estimated to contribute to over 24 percent of nonrecurring delay. Although the Highway Capacity Manual (HCM) provides guidance on the capacity impacts for freeway work zones, only simplified methodologies are provided for both short and long term freeway work zones where the main distinction between the two is the type of barrier separation. Previous research (MBTC 2025) conducted by the Arkansas Highway and Transportation Department (AHTD) during the 1999 Interstate Rehabilitation Program (IRP) found that there are many other factors influencing delay in freeway work zones. The need to consider other factors such as truck percent, work zone configuration, work zone duration, work time, work day, presence of enforcements, intelligent transportation systems (ITS), and construction activities and intensity, etc. in estimating work zone capacities has long been recognized in the industry. However, no defined methodology and guidance have been included in the HCM. Existing analysis methodologies such as the Highway Capacity Manual that predict highway capacity through work zones do not specifically consider impacts of high volumes of heavy vehicles, temporary reduced lane width geometry and design, and activity at the construction site based upon local conditions. Title 23 Code of Federal Regulations Subpart J - Work Zone Safety and Mobility requires that all states develop procedures to address work zone delays. Accurate prediction of highway work zone capacity is necessary to estimate travel delays, vehicle speeds and queuing patterns, and associated congestion. The prediction of traffic flow and congestion through work zones is complex and with many variables. There are many reasons for inaccuracies in the estimation of highway work zone capacities. In addition to the reasons noted above, highway work zone capacities are affected by the type of construction and maintenance activities, duration of lane closure, adverse weather conditions and highway incidents. In addition, two definitions have been used for work zone capacities: pre-breakdown flow rate and post-breakdown queue discharge rate. Both are useful in analysis of work zones where the pre-breakdown flow rate helps with predicting the onset of congestion in a work zone, while the post-breakdown queue discharge rate helps with estimating the operations and queuing patterns after breakdown has occurred. This research will provide a mechanism to collect and analyze field data, determine local highway work zone capacity ranges for a specified set of field conditions and correlate the findings with similar research being conducted for highway work zones in other States efforts nationally. Arkansas highways carry a disproportionately high volume of heavy vehicles, particularly on its rural freeways, where trucks commonly comprise more than 40 percent of average daily traffic. In urban areas, heavy trucks can comprise up to 20 percent of the vehicle mix on an average day. High truck volumes combined with temporary alterations in roadway geometry and traffic flow characteristics specific to the State of Arkansas can adversely affect the highway capacity through work zones, resulting in increased travel delays. With implementation of the State's Proposed 2011 Interstate Rehabilitation Program 2 (IRP), which will rehabilitate approximately 455 miles of Interstate Highway in Arkansas, better methods to calculate work zone capacity are needed at a time when opportunities to observe highway work capacity for a variety of highway types will increase in both urban and rural settings. To establish base conditions and effectively predict highway work zone capacity, field data collection and documentation of local traffic characteristics are needed. This Research is intended to focus upon highway work zone capacity and travel delay in relationship to both existing and temporary work zone highway, the number and width of the typical lanes compared to the number and width of lanes remaining open during work zone activity, and to document how heavy vehicles adversely impact highway work zone capacity and result in congestion.


    • English


    • Status: Active
    • Funding: $88903.00
    • Contract Numbers:


    • Sponsor Organizations:

      Arkansas Department of Transportation

      P.O. Box 2261
      Little Rock, AR  United States  72203
    • Project Managers:

      Rhodes, Dorothy

    • Performing Organizations:

      Arkansas Department of Transportation

      P.O. Box 2261
      Little Rock, AR  United States  72203
    • Principal Investigators:

      Siskowski, Daniel

    • Start Date: 20120701
    • Expected Completion Date: 0
    • Actual Completion Date: 20140630
    • Source Data: RiP Project 32771

    Subject/Index Terms

    Filing Info

    • Accession Number: 01542993
    • Record Type: Research project
    • Source Agency: Arkansas Department of Transportation
    • Contract Numbers: TRC-1306
    • Files: RiP
    • Created Date: Nov 1 2014 1:41AM