This category of repair includes either shimming/leveling and/or milling an existing roadway pavement to create a uniform profile and cross-section before adding or replacing a new HMA riding surface. Milling and shimming depths vary depending on the condition of each roadway, but range from 1 inch to 2 inches. We typically replace or add 1.5 inches to 2.5 inches of HMA over the prepped surface. This repair alternative is reserved for streets with a PCI from 50 to 70. Higher-volume candidate streets may have moderate surface distresses such as cracking and raveling, but with no apparent subbase issues. We aim to employ shim and overlaying on lower-volume streets with moderate surface distresses and minor rutting. It is important to note and set the public's expectation if a candidate street presently has no drainage infrastructure and minor puddling then any repair strategy including only shim/mill and overlay will not necessarily fix the drainage and puddling issues. Proper stormwater management is crucial to extending the life of a street but it is cost-prohibitive to install piped drainage systems on every road we pave. The primary goal of the shim and overlay alternative on low-volume roads is to provide a uniform cross-section/profile and enhanced structure and rideability. We expect to extend a pavement's life around 12 to 15 years with shimming and/or milling and overlay.
