Journal Article•
Benchmarking the structural condition of flexible pavements with deflection bowl parameters : technical paper
01 Jun 2008-Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese (South African Institution Of Civil Engineering (SAICE))-Vol. 50, Iss: 2, pp 2-9
TL;DR: A semi-mechanistic, semi-empirical analysis technique has been developed in South Africa in terms of which deflection bowl parameters, measured with the falling weight deflectometer, are used in a relative benchmarking methodology in conjunction with standardised visual survey methodology to give guidance on individual layer strengths and pinpoint rehabilitation needs.
Abstract: The falling weight deflectometer (FWD) is used worldwide as an established, valuable, nondestructive road testing device for pavement structural analyses. The FWD is used mostly for rehabilitation project level design investigations and for pavement management system (PMS) monitoring on a network basis. In project level investigations, design charts based on both empirical relations and mechanistic or theoretically based approaches are often used to provide structural evaluations and rehabilitation options. The full mechanistic approach normally uses multi-layer linear elastic theory and back-calculation procedures that have come under scrutiny owing to the inaccuracy of results. A semi-mechanistic, semi-empirical analysis technique has been developed in South Africa in terms of which deflection bowl parameters, measured with the FWD, are used in a relative benchmarking methodology in conjunction with standardised visual survey methodology to give guidance on individual layer strengths and pinpoint rehabilitation needs. This benchmark methodology enables the determination of the relative structural condition of the pavement over length and in depth without the requirement for detailed as-built data. A further correlation study with calculated surface moduli and deflection bowl parameters is presented here for granular base pavements, which can enhance benchmarking methodology.
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TL;DR: A relationship between deflection bowl parameters derived from Falling Weight Deflectometer and two pavement performance indices are developed by the use of Artificial Neural Network (ANN) and regression models which indicate that using both IRI and PASER indices leads to accurate structural pavement evaluation.
Abstract: Evaluation of pavement condition, which determines pavement maintenance and rehabilitation necessities, is inevitable using structural or non-structural methods. Since factors such as cost and time required for testing limit the use of structural assessment devices, the development of cost-effective methods should be investigated. In this paper, a practical solution has been presented for pavement structural evaluation which is considered as a useful method for assessing pavement layers condition and identifying rehabilitation needs. With this in mind, we developed a relationship between deflection bowl parameters derived from Falling Weight Deflectometer (FWD) and two pavement performance indices, International Roughness Index (IRI) and Pavement Surface Evaluation and Rating index (PASER), by the use of Artificial Neural Network (ANN) and regression models. To obtain the required data, project field surveys were conducted from 318 sections of the main roads of Kermanshah and Ilam provinces in Iran. The results show that our model provides a satisfactory correlation between IRI, PASER, and structural indices which are based on deflection measurements. By comparing the results of ANN and regression models, the superiority of ANN performance over non-intelligent models is appreciable. The findings of this study indicate that using both IRI and PASER indices leads to accurate structural pavement evaluation.
48 citations
TL;DR: In this article, an integrated regression analysis is conducted considering both ground penetrating radar (GPR) and falling weight deflectometer (FWD) data with the aim to develop a relationship between GPR-estimated AC thicknesses and FWD deflection indexes.
Abstract: The pavement engineering community has consistently drawn its attention to a broadened utilization of advanced Non-Destructive Testing (NDT) systems for pavement evaluation. Amongst these systems, the Falling Weight Deflectometer (FWD) is designed to measure surface deflections and assess the pavement structural condition, while Ground Penetrating Radar (GPR) is utilized to estimate pavement layers’ thicknesses. An integration of the capabilities of these two separate systems has been considered a powerful resource in pavement evaluation. With this in mind, the present study aims to investigate whether this integration could result in the utilization of the derived FWD deflection data to directly assess pavement layers thicknesses. For the research, an integrated regression analysis is conducted considering both GPR and FWD data with the aim to develop a relationship between GPR-estimated AC thicknesses and FWD deflection indexes. The developed relationship is calibrated considering both GPR and core thicknesses and further validated yielding an equivalent and satisfactory performance, with thickness prediction errors around 10%. This finding produces evidence in support of the statement that deflection data is capable of roughly producing pavement layer thicknesses. Such an approach could suggest a practical and cost-effective pavement evaluation tool, when the procurement and transportation logistics of implementing multiple and expensive equipment may be a critical issue.
32 citations
TL;DR: The application of non-destructive testing devices such as Falling Weight Deflectometer (FWD) provides crucial estimates of pavement health that assist in the optimisation of pavement management system.
Abstract: Applications of non-destructive testing devices such as Falling Weight Deflectometer (FWD) provide crucial estimates of pavement health that assist in the optimisation of pavement management system...
29 citations
01 Jun 2012
TL;DR: In this paper, the authors developed an approach for incorporating techniques to interpret and evaluate deflection data for network-level pavement management system (PMS) applications and developed guidelines for the application of recommended techniques and procedures for determining optimum falling weight deflectometer (FWD) test spacing and data collection frequency.
Abstract: The objective of this study was to develop an approach for incorporating techniques to interpret and evaluate deflection data for network-level pavement management system (PMS) applications. The first part of this research focused on identifying and evaluating existing techniques, seeking out those that were simple, reliable, and easy to incorporate into current PMS practices, as well as those that produced consistent results. The second part of the research detailed the development of guidelines for the application of recommended techniques and procedures for determining optimum falling weight deflectometer (FWD) test spacing and data collection frequency. While there are many viable techniques available for evaluating the structural capacity of pavements that use FWD for project-level analysis, many of these techniques are time consuming and require an experienced analyst. As a result, using pavement deflection testing for network-level analysis has been limited to date. This guide provides information for the assessment of pavement structural performance for PMS applications. It reflects the general findings presented in the accompanying final report, Simplified Techniques for Evaluation and Interpretation of Pavement Deflections for Network-Level Analysis (FHWA-HRT-12-023).
28 citations
TL;DR: The adequacy of DBPs to assess the structural condition of individual pavement layers was first assessed through Finite-Element Modelling, and DBPs were established as adequate alternatives for making network-level pavement assessment decisions.
Abstract: Decisions regarding the selection and implementation of appropriate pavement rehabilitation methods is usually based on pavement functional and structural condition data. Visual distress surveys an...
27 citations
References
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Book•
01 Jan 1998
TL;DR: In this article, different analytical models, including Finite Element and Distinct Element Methods, are described and their shortcomings and their lack of validation are discussed, and equally important models of structural and functional deterioration, and how these may be combined with climatic variations and dynamic loading in a stochastic simulation of pavement deterioration.
Abstract: Different analytical models, including Finite Element and Distinct Element Methods, are described and their shortcomings and (lack of) validation are discussed.Further the book describes the equally important models of structural and functional deterioration, and how these may be combined with climatic variations and dynamic loading in a stochastic simulation of pavement deterioration.Finally the book also touches upon surface characteristics, user effects and optimization for use in Pavement Management Systems.
140 citations
01 Nov 2006
TL;DR: In this paper, a semi-mechanistic semi-empirical analysis technique has been developed in South Africa whereby new deflection bowl parameters measured with the FWD used to give guidance on individual layer strengths and pinpoint rehabilitation needs.
Abstract: The falling weight deflectometer (FWD) is used world wide as a well established and valuable non-destructive road testing device for pavement structural analyses. The FWD is used mostly for rehabilitation design investigations and for pavement management system (PMS) monitoring on a network basis. On project level investigations, both design charts and mechanistic approaches using multi-layered linear elastic theory and back-calculation procedures are often used to provide structural evaluations and rehabilitation options. As an alternative to this a semi-mechanistic semi-empirical analysis technique has been developed in South Africa whereby new deflection bowl parameters measured with the FWD used to give guidance on individual layer strengths and pinpoint rehabilitation needs. This approach is fully suited to supplementary analysis of FWD data in the Australian design systems, and overcomes some of the limitations of the curvature parameter. This paper briefly describes the current practice and basis of this use of deflection bowl parameters, and illustrates the use with a current pavement rehabilitation project underway in South Africa.
45 citations
Dissertation•
01 Apr 1987
44 citations
01 Jan 1987
TL;DR: In this article, the authors verify an analysis procedure using measured deflection basins as basic input to calculate various deflection basin parameters and relate them to behavioural changes of typical flexible pavements.
Abstract: The mechanistic design procedure in South Africa and the accelerated testing with the fleet of Heavy Vehicle Simulators (HVSs) provided a unique opportunity to verify an analysis procedure using measured deflection basins as basic input It was possible to calculate various deflection basin parameters and relate them to behavioural changes of typical flexible pavements Two basic flexible pavement types, bitumen base and granular base pavements, were identified These pavement types were analyzed over a wide range of input parameters found in practice The deflection basin parameters calculated were related to the typical distress determinants, namely, subgrade vertical strain and maximum horizontal asphalt tensile strain Deflection basin parameters were also related to other structural input parameters to facilitate proper material characterization Remaining life can be calculated for these distress determinants and the choice of overlay thicknesses can be based on mechanistic analysis
25 citations
01 Jan 1989
12 citations