PERFORMANCE ANALYSIS OF OVERLAID FLEXIBLE PAVEMENTS

Abstract

The conclusion of the road network is of vital importance to the economy of any country. The task of the highway authorities is to maintain the system to those standards that will provide for the lowest overall operating costs of transportation, with special reference to pavements.' Ideally, all activities associated with the planning, design, construction, maintenance, evaluation and research of pavements should be considered and all costs, including social and political "costs" should be included. Traditional design systems are of limited value in this context. A pavement design system (or rehabilitation design system) should therefore not only indicate the structure needed in order to prevent an unaccep- - table degree of deterioration before a given time or number of traffic loadings. This is the minimum requirement of a design method. But it should also permit a prediction of both the "Functional" and "Structural" deterioration over time. Functional condition has to do with the riding quality and structural condition with the structural adequacy. The second step is the prediction of the "performance", i.e. the future functional and structural condition. This is achieved by using an empirical relationship between the response and the rate of deterioration. It is quite important to make this distinction between response and performance and to be aware of the difficulties associated with each of these steps. To deter-mine a pavement's "structural adequacy", it is not sufficient to measure or calculate the response to a given load. The second step is just as important and is often rather more difficult to achieve than the first.