PURPOSE OF MANUAL This manual of practice presents information to guide pavement design engineers in making decisions and using the MEPDG for new pavement and rehabilitation design. The manual does not provide guidance on developing regional or local calibration factors for predicting pavement distress and smoothness. A separate document@ Standard Practice for Conducting Local or Regional Calibration Parameters for the MEPDG@ provides guidance for determining the local calibration factors for both HMA and PCC pavement types (NCHRP@ 2007.b).