AASHTO R 40-05

The rod and level can be used to accurately measure the profile of a pavement. The profile data can be used to evaluate the roughness of the pavement by computing a roughness index such as international roughness index (IRI) or to evaluate effects such as frost heave or swelling of soils. In computing roughness indices, only the relative elevations and not the absolute elevations are needed. The guidelines in this practice can be applied to conventional survey equipment such as an optical level and graduated staff, which require the readings to be manually recorded, as well as automated equipment which is capable of automatically storing the measured data.