The fourth AASHTO Pavement ME National Users Group Meeting last week provided engineers and other stakeholders the opportunity to discuss issues related to mechanistic-empirical (ME) pavement design. 

Key topics include the long-standing ME Pavement Design Guide as well as the AASHTOWare Pavement M-E Design program. Eric Ferrebee participated in the meeting and had the opportunity to talk with designers and key officials about ACPA’s perspectives on highway pavement design. ACPA has long advocated for the use of AASHTOWare’s Pavement ME for highway pavement design. We have also encouraged designers to make the transition from older AASHTO design programs.  

This meeting, which drew close to 90 participants representing 35 State DOTs and Canadian Provinces, is the largest gathering for state DOTs, AASHTO and FHWA to focus solely on AASHTOWare’s Pavement ME Design tool. 

“The design tool is the most advanced tool for designing and analyzing pavements that exists,” Eric says. “This has led to more realistic designs for concrete pavements.” Currently, because of complexity of the tool, many agencies are still working toward implementation, he says. 

“While there are quite a few agencies that have implemented it for concrete, others are still working through calibration efforts to ensure designs match with local performance,” Eric says. “For concrete pavements, we’ve seen that the lack of calibration can result in increased pavement thicknesses, sometimes between 0.5 in. to 1.0 in.  Even so, this is a significant decrease over the earlier empirical versions of the AASHTO design guide (i.e., AASHTO93, AASHTO86 and even AASHTO72). Those versions could result in variations that could add 2 to 3 in. to thickness designs.”  

“Moving toward Mechanistic-Empirical design is a big step for DOTs, but it can help create realistic and competitive designs for concrete,” he adds.

ARA has developed a new Calibration Assistance Tool (CAT), which many participants expressed interest and excitement about.  The tool should help ease some of the issues with calibrating the tool for local use. Designers and others a chance had an opportunity to see CAT demonstrations and to discuss issues with the tool, as well as overall implementation.