DEVELOPING AN OPERATIONAL PAVEMENT DESIGN AND MANAGEMENT SYSTEM AND UPDATING IT WITH ELASTIC THEORY

Pavement design is a complex soil structure interaction problem involving variables in the broad categories of load, environment, construction, maintenance, materials, economics, geometric configuration, and performance. A great deal of effort has been expended in the study of pavement behavior and performance, including full-scale testing such as the AASHTO Road Test. Unfortunately, no long-term coordinated effort has been made to develop comprehensive methods of pavement design and management. Governmental agencies involved with highways are usually divided administratively into design, construction, and maintenance sections. This typically results in dissection of the physical problem with little or no attention paid to the interrelationship between design, construction, maintenance, and management. The general format of most existing procedures for pavement design revolves around the determination of layer thicknesses. Other design details are subsequently adjusted in accordance with these thicknesses. Details such as pavement type, thicknesses and schedules of overlays, maintenance and seal coat requirements, traffic handling during maintenance operations, and selection of the optimum design strategy are usually never considered in present design methods. This paper concerns a systems method of pavement design and management which uses a computer to analyze many phases of the pavement design problem. Two major parts essential to pavement system development are included: (1) an initial system which actually works and which can be used for initial design and further study, and (2) a concept and functional method for continuous study and updating of the system as required. The program presented herein used over 50 input variables and analyzes a great number of possible solutions, generated within the boundary constraints. The output is an order set of pavement design strategies which can be used by the administrator in making a rational design decision. An important part of any pavement design system involves upgrading it to include the best possible technology. The feasibility of upgrading the working systems model is demonstrated through an example whereby the structural subsystem of the design method is improved using elastic layer theory, fatigue concepts, and stochastic variations of material properties. A new mechanistic model is developed, based on the primary distress manifestation of cracking. This model will replace the empirical relationship used at present to simulate a gross transformation between the input variables and the performance of a pavement. /Author/