Trenching, coring, and augering have been used in forensic and routine pavement evaluation to determine the source of the problematic layer or layers and acquire materials for further laboratory testing. For example, a section of US 281 had severe rutting, and the district expressed a need to determine the source of the rutting. Although FWD and GPR tests were performed, evaluation of the data could not differentiate from which layer(s) the rutting came. Trenching provides a viable option. Figure 4-16 illustrates the pavement section profiles on US 281. Chalk and stringlines were used to differentiate pavement layers, as shown in Figure 4-16 and Figure 4-17. By exposing the pavement layers, the rutting was found to be restricted to the surface HMA layer.