Prediction of Flexible Pavement Deflection Based on Falling Weight Deflectometer, FWD, for Highways Traversed by Heavy Overloaded Vehicles (Case Study on Arterial And Collector Roads in Tuban, East Java, Indonesia)

Falling Weight Deflectometer, FWD, is the most popular equipment used to measure the deflection of flexible pavement in Indonesia. The loading used during application of the FWD equipment generally correlates directly with those of the loads of standard heavy vehicles. Therefore, the resulted pavement deflections obtained from the tests should be also suitable for highways traversed by standard normal vehicles only. This may not be the case for highways in Indonesia, where most trucks are highly overloaded, so much beyond the allowable standard loads. The existing method of FWD test may not be representative anymore to measure the actual pavement deflections under highly overloaded vehicles. In this paper, the authors describe their findings about deflections of flexible pavement when the pavements were subjected by heavily overloaded vehicles. The first step is to modify the FWD equipment with larger falling distances and heavier loads to simulate the highly overloaded vehicles in Indonesia. Based on the results and by using statistical approach, a new mathematical equation can be derived to reflect the functions of actual pavement deflections under much higher loads when compared to those of standard normal load. Therefore, using this new equation one can predict the actual pavement deflection under highly overloaded vehicles, by just performing standard FWD test of standard loads on the pavement, so that the design of overlay thickness can be modified accordingly to be applicable to overloaded traffic in Indonesia