In the late 1990s, the National Cooperative Highway Research Program (NCHRP) initiated a project to develop a state-of-the-practice tool for the design of new and rehabilitated pavement structures. The major objective of this NCHRP 1-37A project was to develop a document for adaptation by AASHTO as its new Mechanistic-Empirical Pavement Design Guide (MEPDG) for new and rehabilitated pavement structures. The development of the new AASHTO MEPDG and its supporting software DARWin ME (later re-named to Pavement ME Design), has changed existing pavement design procedures, but would need to be adapted and calibrated for local conditions. In preparation for the release of this new tool, the Pavements and Soils and Materials Standing Committees of the Transportation Association of Canada, initiated a Pool Fund project to provide guidance to Canadian agencies on adaptation and calibration of the MEPDG to Canadian conditions. Initiated in April of 2004, the project steering committee began by developing a road map that identified short and long term requirements and resources needed to implement the MEPDG in Canada. The calibration process began with the development of a database of historical Canadian climate information for various locations across the country, which has since been included in Pavement ME Design. Other project tasks followed thereafter including a review of traffic inputs and numerous workshops. To further help the project steering committee in determining future project requirements, and to share knowledge in using the design tool, a user group was formed in 2008. As a way to become more familiar with using the Pavement ME Design program the user group began running trial designs and comparing the variability in results. A flexible pavement design was provided by Manitoba Infrastructure and Transportation that was used as the base design. This base design was modified for various climate stations across Canada, while keeping all other input parameters consistent. Design trials were then completed by changing the season in which the pavement structure was constructed, followed by evaluating the impact of changing asphalt cement grade in the asphalt mixtures. The objective of this paper is to present the results of the trials completed by the TAC Pavement ME user group, and highlight some of the findings of the analysis.
