Viability of Vehicle Length in Estimating Vehicle Classification and Axle Factors

The primary objectives of this project are to understand the accuracy of axle factors determined from vehicle length and to develop and evaluate methods for converting length data to axle-based classifications. Phase I of project TPF 5(340) assessed alternative methods to estimate axle factors and vehicle class from length-based data. The two best performing methods (Method 1 and Method 5) were further evaluated using an additional dataset from the nationwide Long Term Pavement Performance Program (LTPP). Based on the results of the final round of evaluations, the performance of the two recommended methods was found within the expected limits of performance. Phase II of this project develops and evaluates an implementation plan for Method 1 and Method 5. Since Method 1 is more straightforward with its methodology, its application is not as complicated to complete. Method 5, though, requires more complex mathematical applications, such as parametric functions and algorithm development, and the need for an automated application was identified. A data processing tool was developed to aid analysts in estimating axle factors and vehicle class using Method 5 techniques. The user inputs the raw traffic data inputs and the tool, with default “seed” data collected in Phase I of this project, estimates vehicle classes and axle factors for that site. The seed data used for the data processing tool is representative of the data inputted; therefore, consideration should be given to review and update the seed data, as needed. For example, seed data could be updated to reflect a specific region or highway characteristic so a more accurate representation of vehicle class can be applied to input data. As a test of the data processing tool, traffic data from ten collocated test sites in Wisconsin were inputted into the data processing tool to evaluate the tool’s ability to estimate Federal Highway Administration (FHWA) vehicle classes from length-based data.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report - Phase II
  • Features: Appendices; Figures; Maps; Tables;
  • Pagination: 34p

Subject/Index Terms

Filing Info

  • Accession Number: 01717165
  • Record Type: Publication
  • Contract Numbers: TPF-5(340)
  • Created Date: Aug 26 2019 8:30AM