2017 Enhancements

August 01, 2017
Enhancements Impact on Calibration Coefficients

None of the FY2017 enhancements have any impact on the transfer function calibration coefficients.

MEPDG Manual of Practice​

The Mechanistic Empirical Pavement Design Guide (MEPDG) Manual of Practice (MOP) is now integrated into the Pavement ME Design software. Specifically, the MOP is dynamically and contextually linked to the data elements within the software. The user simply clicks on the MOP help icon, selects a material property in the user interface, (such as thickness), and the program looks up the selected control based on its “Name” property in the XML file object. If more than one possible selection is available, a dialog appears allowing the user to choose the help item of interest. The system uses all information available regarding the selected design type.

Deflection Analysis and Backcalculation Tool

A new external utility tool (Pavement ME Design Pre-processing and Backcalculation Tool or BcT) has three major elements that can be executed separately and in an automated manner with the Pavement ME Design software.
Element 1—Pre-processing Deflection Data Tool for Backcalculation – This element consists of three analysis features:
  1. Convert deflection data into the required format: The first analysis feature is simply a pre-processing tool that is used to convert the raw Falling Weight Deflectometer (FWD) deflection data into the required text file formats for further use as input into the backcalculation analysis program. This feature allows an agency using some of the older deflection measuring equipment to still convert raw data files into the format needed.
  2. Clean the data: The second analysis feature is used to review the deflection data to identify problem basins, errors, and other items that may cause problems when performing backcalculation analyses or when importing the data into the Pavement ME Design files.
  3. Project segmentation: The third analysis feature is the project segmentation tool that identifies analysis segments. This feature enables the user to accept, reject, or modify the recommended segmentation scheme. Specifically, this feature segments the rehabilitation project into practical design sections based on the deflection basin data and results from destructive sampling and testing (cores and borings, as well as physical features in a project).
Element 2—Backcalculation of Stiffness Values:

This feature is the actual backcalculation process provided in the Evercalc program. The input deflection data files generated from Element 1 are automatically imported directly into the backcalculation program. Alternatively, the raw deflection file that is generated can be used if the user chooses a specific backcalculation program other than Evercalc.

Element 3—Post-processing Backcalculation Results:

The final element of the backcalculation tool is used to post-process the backcalculated elastic modulus values. It creates the input files to Pavement ME Design based on the information from the first two elements. The files imported into the Pavement ME Design program include both the backcalculated modulus data and the layer structure information to define the existing structure. This information is supplied through the backcalculation.xml and bcstructure.xml files. The pre-processing-backcalculation utility tool can be launched independently without interfacing with the Pavement ME Design program.

APIs for Selected Executables (Available)  

Application Programming Interfaces (APIs) were created for two analysis executables: Modulus for creating the asphalt concrete (AC) modulus master curves and TCModel for calculating transverse cracks in flexible pavements:
  • AC modulus master curves: Dynamic modulus does not have any dependencies and can be run independently from a Pavement ME Design analysis or project. The new API assists users in evaluating the dynamic modulus test data prior to entering the data into the software. It takes dynamic modulus inputs (as a grid) and calculates A and VTS as well as the seven parameters for the dynamic shear rheometer for AC mixtures. The API can also be used to determine the statistical parameters from deriving the parameters for the master curve within the software as a measure for judging the fit to the master curve.
  • TCModel: TCModel explains the development of transverse cracks in various climatic regions. This API allows users to programmatically read and process all TCModel outputs. This API is directly applicable for evaluating and assisting in resolving the difference between the occurrence of transverse cracks caused by a cold temperature event and those caused by other mechanisms.

Fixes to Errors And Discrepancies from the Technical Audit 

The Pavement ME Design Task Force authorized the first technical audit of the software in FY2016. A few errors and discrepancies were identified, and all of these were fixed in FY2017. Eight issues were identified that impact the predicted distresses for flexible and semi-rigid pavements. As a result, a global recalibration of the flexible and semi-rigid pavements is planned under the FY2018 work plan.