ABSTRACT
High and long-lasting serviceability for roads and motorways is reasonably expected by users and operators. Serviceability is mainly conceived as an environment-friendly blend of ride quality and safety, in which pavement life-cycle performance plays a significant role.
In the frame of rational management of road networks, public authorities and private operators have to define acceptance values for the main pavement surface characteristics. Each national policy may be conducted either in terms of national design standards or in accordance with specifications of general application (EN – European Norms, ASTM – American Standards). Threshold values for pavement characteristics are, in most cases, derived from a combination of subjective pavement performance ranking with relevant experience in site monitoring.
Generally, long-term pavement performance depends on a number of variables such as traffic volume, heavy and overweight vehicle rate and climatic conditions. In this regard, a rational road design, aiming to an effective and cost-saving management, must go much further: instead of adopting limit values of empirical character for pavement features, an analytical methodology may be applied to define respective acceptance criteria.
An analytical approach to provide sustainable limit values for pavement surface characteristics is presented herewith. Skid-resistance, roughness and rutting are herein considered as indicators of safety, comfort and travel cost. Threshold values are derived from analytical formulas in relation with traffic loads. The quintessence of this paper stands for outlining the concept to define threshold values for pavement characteristics at the initial stage (‘opening to traffic’) as well as at the operational stage of a road lifetime. Through this analytical approach, a road pavement design will establish an enduring high performance of the roadway and minimize maintenance operations and respective financing required.
