An alternative deflection analysis for the evaluation of the pavement condition

Abstract

During the last two decades Portugal has been developing extensively its national transport network by constructing numerous new highways. Presently, this network is about to be concluded and the main investment of the Portuguese state resides in its operation and maintenance. In order to manage more than 15.000 km of national roads, an efficient and quick method must be used to evaluate the pavement condition. This is essential to decide where and when the major maintenance investments should be applied, as well as to preserve the entire network with a high service level. That method must contemplate the observation of the surface distresses in the pavement combined with the use of the Falling Weight Deflectometer (FWD) to evaluate the structural state of roads. The analysis of deflection bowls obtained with the FWD is a crucial phase in the road management process. Currently, FWD tests are carried out in arbitrary points usually staggered every 100 meters. However, pavements are continuous and their structural condition can show a high deviation in a few meters. Moreover, the final analysis of the pavement condition is based on characteristic deflection bowls of its homogeneous sections. This analysis can overestimate the importance of some singular points, resulting in maintenance costs over the real needs. This work presents a new approach to evaluate the pavement condition based on deflection bowls by using a case study with two highway sections whose pavements present different surface and structural conditions. The main conclusions of this work are related to the comparison between the two methods of analysing the FWD results. The surface distresses of the pavements are also compared with the FWD results, in order to validate the new approach of assessing the pavement condition.