The design of asphaltic concrete overlays on penetration macadam pavements in Indonesia

Asphaltic concrete overlays on existing penetration macadam pavements have been successfully used in Indonesia to decrease pavement roughness and to increase pavement durability. Conventional western overlay design methods give, however, large overlay thicknesses which are too expensive to adopt country wide. The use of thinner asphaltic concrete overlays was therefore studied by examining all available pavement deflection- life relationships, the performance of AC overlays already constructed in Indonesia and the economics of various pavement alternatives taking all construction, maintenance, congestion and vehicle operating costs over the analysis period into account. The analysis indicated that thinner asphaltic concrete overlays based more on the failure deflection criterion than the critical condition were economically desirable. A deflection- life relationship which gives from 20 to 40 per cent higher allowable deflections at any given traffic loading than conventional western deflection criterion was recommended for use in Indonesia. This design method was denoted acodi (asphaltic concrete overlay design for Indonesia) to differentiate it from conventional overlay pavement design methodologies and could be useful for other developing countries where capital is scarce and a less conservative overlay design procedure is required (a).