Crack routing is the process of grinding a channel, usually ¾” wide and ½” deep, into the random crack line. Routing is usually done on cracks that are less than ¾” wide to a width of 1” and ½’ depth. This forms a reservoir with vertical walls for the crack sealant, which is the optimal substrate for crack filling. Routing of cracks is usually required for pavement repair work on federal and state airfields.