Evaluating pavement management treatment selection utilising continuous deflection measurements in flexible pavements

Abstract

The objective of this study was to develop a new structural index based on rolling wheel deflectometer (RWD) deflection data to describe pavement structural capacity and to improve pavement management treatment selection. To achieve this objective, pavement conditions including surface cracking, rutting, roughness and asphalt layer thicknesses were categorised and sorted according to their AC layer thickness and divided into various subgroups. The cumulative distribution function of the new RWD index in each subgroup was generated so that various percentiles were calculated and used to define the boundary between structural and functional rehabilitation. Results showed that the Louisiana criteria may recommend structural rehabilitation for pavements with sound pavement structure (Type I error) and functional rehabilitation to pavements with weak pavement structure (Type II error). Therefore, the state pavement management system should consider both pavement structural indices and surface distress indices currently available when making recommendations for pavement preservation and rehabilitation. RWD testing technology and indices derived from its data are one of the most promising candidates to fulfil this need.

Relationship between Surface-Measured Indices and In-Service Pavement Structural Conditions Predicted from Traffic Speed Deflection Devices

“…As demonstrated in this study, surface indices cannot be used as a reliable predictor of structural capacity, possibly leading to erroneous decision making in treatments’ selection. If no structural condition data are collected or considered by the state to assist in the process of selecting a suitable treatment strategy, it may lead to two types of errors ( 9 ): adding structure to a pavement that does not require it (Type I error—False Positive) and not adding structure to a pavement that requires it (Type II—False Negative). Examples of Type I errors include using treatments such as pavement reconstruction, medium overlays, and in some cases thin overlays on pavements that are not structurally deficient and that only need functional repairs.…”

“…Methodologies for backcalculation of subgrade moduli based on RWD measurements and layer moduli based on TSD measurements were developed ( 6 , 7 ). In addition, a framework was developed to incorporate RWD measurements in the Louisiana pavement management system (PMS) at the network level and in asphalt concrete (AC) overlay design at the project level ( 8 , 9 ).…”