Minnesota Department of Transportation (MnDOT) upgraded its MnPAVE-Rigid 1.0 software for concrete pavement design. MnPAVE-Rigid 2.0 is now easier to use and allows designers to select from more options for aggregate base types and thicknesses, and incorporate specific traffic values. “In the original software, we only allowed one aggregate base thickness and one aggregate type. MnPAVE-Rigid 2.0 allows 2 base thicknesses and 3 base types,” said Tim Andersen, Pavement Design Engineer-MnDOT Office of Materials and Road Research.
WHAT WAS THE NEED? In 2014, MnDOT developed its own pavement design software, MnPAVE-Rigid that incorporated the methodology of the American Association of State Highway and Transportation Officials (AASHTO) Mechanistic–Empirical Pavement Design Guide (MEPDG). Minnesota’s pavement designers use MnPAVE to apply AASHTO’s most sophisticated design principles for both rigid and flexible pavement, focusing on mechanical properties of the pavement and prevention of early cracking and other distress. AASHTO’s mechanistic—empirical (M–E) design methods entail hundreds of inputs, each a:
• Mechanical parameter
• Measure of site-specific characteristics or
• Design goal
AASHTO’s M–E design software offers various input levels to reduce the data gathering and input burden—simplifying the input selection process. The most basic level uses default values for most of the inputs based on national averages, but still requires dozens of inputs for the number of pavement layers, traffic expectations, climate, and other features.
MnPAVE-Rigid for concrete pavement design reduced that number of inputs to 9. MnPAVE-Rigid inputs work with a set of default values for jointed plain concrete (selected by the MnDOT Office of Materials and Road Research in 2014). Derek Tompkins, Principal Civil Engineer-American Engineering Testing, Inc., said, “Many states ignored the challenge of adopting AASHTO M–E or they bought an AASHTO software license. MnDOT used its accumulated knowledge of AASHTO M–E and Minnesota conditions to build MnPAVE-Rigid, and so can account for its M–E design results firsthand.”
Since 2014, when MnDOT implemented MnPAVE-Rigid 1.0, they have gathered feedback from users about their experience with the software. In the current project, MnDOT wanted to address this feedback, and expand and improve the original software by exploring additional options with some of the default parameters for concrete pavements.
WHAT WAS THE GOAL of MnPAVE-Rigid 2.0? To update MnPAVE-Rigid 1.0 by expanding the range of inputs for traffic, subgrade type, base type and thickness, and to make the user interface more accessible.
WHAT WAS IMPLEMENTED in 2.0? The upgraded software —MnPAVE-Rigid 2.0—allows users to:
• Enter 11 inputs—including those related to specific traffic levels and aggregate base types
• Calculate the new design thickness
• Print a project report that summarizes the inputs and the recommended thickness
• Have more user-friendly software, while the MnDOT maintains it and/or makes future source code upgrades
HOW WAS IT DONE?
• Researchers met with the Technical Advisory Panel and reviewed the list of software improvements requested by pavement designers and the MnDOT Office of Materials and Road Research.
• Investigators ran over 21,000 simulations to analyze the impact of changes made to inputs for base type, base thickness, subgrade type and traffic level.
• The research team modified the traffic input calculator to allow designers to enter traffic values from MnDOT’s weigh-in-motion and traffic counting data. The calculator runs input traffic data in software simulations and assigns the input an appropriate axle value for design.
• The code developer modified elements of the advanced inputs tab and PDF report generation features to improve performance for software users.
• The code developer rebuilt the software in JavaScript 2.0 code, including an installer for use with Windows software.
What Was the Impact? MnPAVE-Rigid 2.0 is more user-friendly.
• Tabs better match designer needs
• Software offers a design report PDF file for export
• Users can now input traffic data that the software will categorize
• Designers can input Class 5 aggregate, Class 5Q (a higher quality aggregate with fewer fines), and open-graded aggregate (no fines)
• Users can also choose 4- or 12-inch aggregate base thicknesses
The the AASHTO M–E software is expensive, so agencies that use it work closely with consultants to receive training and to explore or modify the code. MnDOT owns and manages the source code for MnPAVE-Rigid 2.0, can keep it secure, and can continue to change and upgrade it internally for Windows and Linux platforms.
WHAT’S NEXT? It is essentially already in use. But, after MnDOT designers around the state fully review the software, the Office of Materials and Road Research will post a link to the program on its website. Presentations about the software upgrades will be made at meetings for materials and soils engineers through the fall of 2018.
This Implementation Summary pertains to Report 2018-17, “MnPAVE-Rigid 2.0,” published May 2018. For the entire “Crossroads”-MnDOT Transportation Research Blog, please go to: https://mntransportationresearch.org/2018/07/27/upgrading-mnpave-rigid-design-software/
Home page photo: “Crossroads”-MnDOT Transportation Research Blog”
Image from M–E pavement design methods from MnPAVE-Rigid 2.0 software—
MnDOT engineers design durable, high-performing concrete pavements: