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South Dakota Department of Transportation
Project Synopsis
SD1999-13


Title: Weigh-in-Motion Calibration and Overweight Estimation
Project Researcher: Dave Huft, SDDOT
Project Manager: Brian Hines
Research Period: 5/10/1999 - 8/30/2000
Status: Approved
Cost: $20,000.00

Problem Statement: The SDDOT has used Weigh-in-Motion (WIM) systems since 1985 for providing data for future pavement designs and pavement life expectancies. SDDOT currently has two types of WIM systems, commercial bending plate WIM system and a system developed by SDDOT for use on bridges. These WIM systems have not been calibrated since their installation. Therefore, SDDOT is not sure how reliable the traffic load estimates are.

Even with a WIM system calibrated, there is some variability in the measurements. In order to better estimate the number of overweight vehicles and collect data for future pavement design, the WIM systems need to be characterized with respect to their variability. For the purpose of the problem statement, the term overweight vehicle is defined as vehicle is overweight by gross weight, group weights and/or the pounds per inch of manufactures tire width. Tire widths and axle spacing are used to determine legal limits for overweight axles, WIM systems have no means of determining tire width, needed to determine the legal load limit.

Research is needed in order to calibrate our WIM systems and get an estimate of the number and magnitude of overweight vehicles.



Findings:

Research Objectives:
1  To develop a method for calibrating bending plate WIM system and a method for characterizing bending plate and bridge WIM system accuracy.
2  To develop a method to estimate the percentage of overweight vehicles and the magnitude of overweight vehicles.
3  To demonstrate the calibration method for the bending plate WIM system and demonstrate the overweight estimate method for the bending plate and bridge WIM systems.

Research Tasks:
1  Perform a literature search pertinent to WIM calibration and overweight estimation.
2  Meet with the technical panel to review project scope and work plan.
3  Propose a method for calibrating and characterizing accuracy of the WIM systems.
4  Meet with the technical panel to review methods for calibrating and characterizing accuracy of WIM systems.
5  Collect static and WIM data.
6  Apply calibration method to data.
7  Propose method for estimating percentage of overweight vehicles and magnitude of overweight vehicles.
8  Apply estimating overweight method to data.
9  Develop software for characterizing WIM system and estimating overweight vehicles.
10  Prepare a final report and executive summary of the literature review, research methodology, findings, conclusions, and recommendations.
11  Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.

Documents Available:

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