Asphalt milling is a process in which a milling machine is used to remove aged / broken asphalt at a specified depth prior to an overlay.  This is a cost-effective alternative to a complete removal and replacement.  By milling, profile and grade corrections can be achieved so that the new overlay has the best potential for drainage and smoothness.  Milling will also restore proper curb-reveal for roads with concrete curb and gutter that are getting an overlay.