Manitoba Infrastructure and Transportation (MIT) has been using the new Mechanistic Empirical Pavement Design Guide (MEPDG) since 2007 in conjunction with traditional design practices. The objective of this paper is to discuss issues and prospects in using this new design tool by using design examples of typical flexible, rigid and composite (asphalt over concrete) pavements. The influence of traffic volume, asphalt, concrete thickness, base thickness, asphalt binder type, subgrade support and base layer strength on the predicted roughness and surface distresses are analyzed to demonstrate the issues and prospects. The approaches that Manitoba is considering in to order to adopt this new tool in conjunction with Manitoba’s local experience are also discussed. Analysis indicates that the default asphalt layer rutting limit of 6 mm is too conservative and the longitudinal cracking model is unreliable. The required asphalt layer thickness could be significantly reduced if the asphalt rutting limit is increased to 12 mm, asphalt longitudinal cracking is ignored and an appropriate asphalt binder is used. In the Pavement ME Design, the base layer exceeding 250 mm and subbase layer are shown to produce no practical influence on the required asphalt thickness. It is recommended that a catalogue of base and subbase thicknesses be developed for frost protection requirement based on local experience. The Pavement ME Design program can be then used to determine the required asphalt thickness. The resilient modulii (stiffness) of base and subgrade are shown to significantly influence the predicted distresses and roughness. The required concrete thickness is shown to be significantly lower than that which Manitoba usually constructs.
