Limits of agreement method for comparing TSD and FWD measurements (original) (raw)
Related papers
A Study of the Structural Performance of Flexible Pavements Using a Traffic Speed Deflectometer
Geo-China 2016, 2016
The falling weight deflectometer (FWD) is a non-destructive testing device that has been used by many road agencies worldwide since 1980 for structural evaluation of flexible pavements. In early 2000, the world first Doppler laser-based traffic speed deflectometer (TSD) was developed by Greenwood Engineering, and now eight TSD vehicles are in use worldwide. The two main advantages of the TSD technology are: (a) the ability to carry out continuous bearing capacity measurements instead of discrete points, (b) that testing can be carried out at traffic speeds without the need for lane closures with a stationary device such as FWD. The objective of this paper was to study the structural performance of flexible pavements using TSD deflection data. The study successfully established a correlation between maximum deflections TSD-D 0 and FWD-D 0 that are derived from the two devices. This study also drew some interesting conclusions in that deflection data collected by TSD could be transformed to FWD equivalent structural numbers with simple models as derived in the study. The outcome of this study was an established methodology for reporting structural performance at network level utilizing TSD deflection data.
A Study of the Structural Performance of Flexible Pavements Using Traffic Speed Deflectometer
Journal of Testing and Evaluation, 2017
The falling weight deflectometer (FWD) is a non-destructive testing device that has been used by many road agencies worldwide since 1980 for structural evaluation of flexible pavements. In early 2000, the world first Doppler laser-based traffic speed deflectometer (TSD) was developed by Greenwood Engineering, and now eight TSD vehicles are in use worldwide. The two main advantages of the TSD technology are: (a) the ability to carry out continuous bearing capacity measurements instead of discrete points, (b) that testing can be carried out at traffic speeds without the need for lane closures with a stationary device such as FWD. The objective of this paper was to study the structural performance of flexible pavements using TSD deflection data. The study successfully established a correlation between maximum deflections TSD-D 0 and FWD-D 0 that are derived from the two devices. This study also drew some interesting conclusions in that deflection data collected by TSD could be transformed to FWD equivalent structural numbers with simple models as derived in the study. The outcome of this study was an established methodology for reporting structural performance at network level utilizing TSD deflection data.
2012
The paper describes a procedure where the condition of flexible pavements is investigated with the help of non-destructive tests such as the Falling Weight Deflectometer (FWD). The condition or indication of structural strength is expressed in terms of the Structural Number (SN). An existing method of determining the Structural Number was used as benchmark with data from a recent detailed pavement investigation. The benchmark SN determination also makes use of the Dynamic Cone Penetrometer (DCP) method. Previously only limited aspects of the measured deflection bowl were used to determine SN non-destructively. In this improved procedure additional deflection bowl parameters were investigated for their possible improvement in the determination of the SN or PN. The proposed method was therefore benchmarked against existing methods to determine SN for a pavement to see if it can lead to an improvement in determining SN values.
REVIEW OF FALLING WEIGHT DEFLECTOMETER FOR ASSESSMENT OF FLEXIBLE PAVEMENT
ELK ASIA PACIFIC JOURNAL OF CIVIL ENGINEERING AND STRUCTURAL DEVELOPMENT , 2018
Fast development of road networks has become a trend in India and everywhere in the world. From the past couple of decades, it has been observed that numerous highways are in a phase of deteriorations. Identifying the reasons for deteriorations requires a pavement evaluation study. Many performances study have been made out by exploring flexible pavements, by the users of widely accepted falling weight deflectometer (FWD) as a non-destructive test (NDT) and considered it as a standard for structure assessment. The primary objective of this study is to a review of an FWD instrument and the also study of the empirically derived methods and a back calculation process for computing layer moduli and factors influencing it. The essential need of correction factors to get reliable layer moduli is an also discussed, in addition to the investigation of advancement of low-cost indigenous FWD models flexible pavements, by the users of widely accepted falling weight deflectometer (FWD) as a non-destructive test (NDT) and considered it as a standard for structure assessment. The primary objective of this study is to a review of an FWD instrument and the also study of the empirically derived methods and a back calculation process for computing layer moduli and factors influencing it. The essential need of correction factors to get reliable layer moduli is an also discussed, in addition to the investigation of advancement of low-cost indigenous FWD models
Review of falling weight deflectometer deflection benchmark analysis on roads and airfields
2015
A benchmark analysis method was developed using Falling Weight Deflectometer (FWD) data for comparative evaluation of the structural condition of flexible pavement structures. This is established as a preliminary design and analysis tool, and aspects of it are incorporated in TRH 12. Experiences with benchmark analyses on roads and airports are reviewed and adjusted criteria are recommended with a colour coded three tiered condition assessment method. Exploratory studies on additional deflection bowl parameters are conducted to gauge their potential for inclusion in benchmark analyses. Deflection bowl parameter benchmarking has found application at network level analysis in a number of road authorities worldwide. Modified Structural Number (SNP) and Pavement Number (PN) have recently also been illustrated as being able to accurately calculate from the full deflection bowl and can be used in such enhanced benchmark analyses of flexible pavement structures.
A benchmark analysis method was developed using Falling Weight Deflectometer (FWD) data for comparative evaluation of the structural condition of flexible pavement structures. This is established as a preliminary design and analysis tool, and aspects of it are incorporated in TRH 12. Experiences with benchmark analyses on roads and airports are reviewed and adjusted criteria are recommended with a colour coded three tiered condition assessment method. Exploratory studies on additional deflection bowl parameters are conducted to gauge their potential for inclusion in benchmark analyses. Deflection bowl parameter benchmarking has found application at network level analysis in a number of road authorities world-wide. Modified Structural Number (SNP) and Pavement Number (PN) have recently also been illustrated as being able to accurately calculate from the full deflection bowl and can be used in such enhanced benchmark analyses of flexible pavement structures.
FALLING WEIGHT DEFLECTOMETER BOWL PARAMETERS AS ANALYSIS TOOL FOR PAVEMENT STRUCTURAL EVALUATIONS
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.
Analytical-Empirical Pavement Evaluation Using the Falling Weight Deflectometer
Transportation Research Record, 1985
Because of the rapid development of hardware and software during the past 10 years, it is now possible to use an analytical-empirical (or mechanistic) method of structural pavement evaluation on a routine basis. The Dynatest 8000 falling weight deflectometer that, when used with the ELMOn program, determines the modulus of each structural layer in a pavement system is described. The moduli are determined nondestructively and in situ under conditions that closely resemble those under the influence of heavy traffic. Some practical examples illustrating the use of the method are presented, and its empirical components are discussed. These empirical components are also programmed into the ELMOD program so an overlay design may be carried out concurrently with the analytical determination of layered elastic moduli. The method may be used for both flexible and rigid pavements, where joint evaluation is not needed. The evaluation of joint or corner conditions in jointed portland cement con...
Young’s Modulus and Deflection Assessment on Pavement Using a Lightweight Deflectometer
International Journal of GEOMATE, 2021
This research implemented direct assessment in the field on road structures using the Light Weight Deflectometer (LWD) method. This method is similar to the Falling Weight Deflectometer (FWD) method. The LWD method uses a lower loads compared to the FWD method. LWD method was chosen because the equipment is quite portable and straightforward allowing it to be used directly in the field, making inspection easier. The LWD method is more suitable for assessing the pavement conditions in which the volume of road use is not too high. This study aims to determine the value of the road structure conditions based on material properties. The location of the survey was Kupang City, East Nusa Tenggara, and Indonesia. The number of test points is 77 main points, with each point consisting of several tests. The test results obtained in this study are the value of deflection and modulus of elasticity at each test point. In addition, a radius of curvature analysis was carried out to determine the base of the pavement structure conditions. LWD testing by giving a load on the surface of the pavement was found to predict the base conditions of the road structure. This study also analyzes the EFWD conversion value from the ELWD test results and the correlation between these methods is presented.