Ride quality has been a fundamental concern of highway users since the earliest days of modern era highway construction. From the vehicle operator’s perspective, the concern is predominantly functional (comfort and safety oriented), but, indirectly, there is a component of ride quality that eventually affects the structural performance of the pavement. Smooth pavement mitigates the magnitude of dynamic wheel loading; the smoother the pavement, the lower the dynamic loading and the resulting harmful responses to loading (deflections, stresses, and strains) within the structure. Ride quality has been integrated into the department’s highway construction procedures as a Standard Specification Item since 1993. The ride quality goal is to begin a pavement structure’s performance period (see Chapter 2, Fig. 2-12) at a high level of smoothness, and maintain it at an acceptable level throughout the design life by judicious use of pavement preservation and rehabilitation efforts. Pavements that begin their performance life in a very smooth condition tend to maintain acceptable smoothness over a longer period of time, all other things being equal. To assess ride quality, a longitudinal profile is evaluated in both wheel paths. The pavement profile is a measure of the variation of elevation differentials of the pavement surface from a reference plane.