Andrzej Pożarycki

Asphalt surfaced pavement cracks detection based on histograms of oriented gradients

Cracks are the most requiring type of pavement distresses to detect and classify automatically. Due to its nature are easily absorbed by other types of pavement surface damages. Moreover, the diversity of pavement surface makes the image detection system requiring efficient computer algorithms. The paper presents the solutions tested on surface distress data which were collected automatically using downward facing cameras placed orthogonally to road pavement axis. Presented results focus on the crack-type pavement distresses. The achieved accuracy of the transverse, longitudinal and meshing cracks recognition based on the initial dataset prepared especially for this system, show it has very good chances to work efficiently with large image datasets collected during the inspection car runs.

Condition assessment of lower roadway layers for pavement management systems

AbstractThe process of selecting road maintenance technologies for the Pavement Management System (PMS) can use road pavement moduli of deformation as the substantiating information. Assessment criteria based on either pavement or base course moduli of deformation have strong empirical underpinning, since the stiff plate bearing testing (SPBT) is commonly used worldwide. This paper discusses potential practical applications of plate bearing test numerical simula- tion based on Falling Weight Deflectometer (FWD) deflection data, and theoretical model based on flexible pavement. It was proven that including a pavement model with stress dependency, the simulated second load-displacement curves meet reliably plate bearing in-situ test conditions for different layers of either subgrade or base courses of road pave- ment. This methodology is feasible by classifying technical condition of each lower layer of road pavement against requirements towards new pavements.

Multi-level backcalculation algorithm for robust determination of pavement layers parameters

The backcalculation procedure applied to a mechanical characterization of the road pavement is usually limited to an identification of the elastic modulus of each layer only. The remaining parameters of the model are usually set as known, while performing an inverse analysis. Among assumed parameters are thicknesses of the model layers and frequently considered as constants on a homogeneous section of the road. This is an obvious simplification, because sections in general are inhomogeneous, i.e. the thickness of each layer changes slightly along each road section. Thus the precise and possibly nondestructive estimation of the layers thicknesses is very important and crucial in the inverse procedure. Here, a hybrid form of the optimization algorithm, where the condition of a constant thickness does not need to be fulfilled is described. Further on, the objective function is formed as a discrepancy between reference and computed deflection derivative instead of a deflection curve. In consequence, the values of backcalculated parameters are several per cent more precise compared to a standard procedure. Whenever the thickness of the asphalt layer of the pavement structure cannot be assumed a priori as a constant, the proposed here method appears to be necessary if one does not want to perform costly and destructive in situ drilling tests.

Backcalculation of pavements incorporating Grouted Macadam technology

Applying cement grout with a high compressive strength to a porous layer made of asphalt concrete results in a pavement with the properties of an intermediate type that combines the characteristics of both flexible and rigid pavements. This solution is known as Grouted Macadam (GM). Despite a wide range of test results on the GM pavements presented in the literature, there are very few advanced modelling solutions formulated in the scope of bearing capacity measured in situ be means of a Falling Weight Deflectometer. This paper turns out that the seemingly small frequency of loading (≈20 Hz) generated during pavement deflection measurements using a Falling Weight Deflectometer-like device, has a significant impact on the backcalculation results of GM pavements. The study shows that, introducing frequency normalisation of both the pavement loading and vertical displacements to the backcalculation, can limit the statistical scatter of backcalculation results by close to a half in comparison with the classical backcalculation procedure.

The influence of frequency normalisation of FWD pavement measurements on backcalculated values of stiffness moduli

Backcalculation is commonly used for determining stiffness moduli of pavement courses and its subgrade based on in situ deflection tests. However, the in situ test results are dependent on the frequency domain, which in turn has a significant influence on the backcalculation results. In this paper, one of the methods for normalising the frequency of load and displacement functions obtained from a dynamic impulse generated by a falling weight deflectometer (FWD) test is verified. The assessment of the method is carried out based on backcalculation results of pavement deflection tests induced by both the dynamic and static loads and an independent numerical experiment. The analysis carried out in this paper shows that the normalisation of vertical displacements and pavement loads to the values corresponding to the frequency of 0 Hz improves the accuracy of the backcalculation results. It can be concluded that the frequency normalisation procedure is an effective way for standardising the boundary conditions in the backcalculation of flexible pavements.

Road structure analysis based on cross-section images processing

Road pavement structure analysis provides important information for road maintenance and renovation planning. Image processing methods applying to cross-section of the asphalt pavement can provide valuable information about the pavement structure and its quality. The paper presents a method to analyze a picture of a cross-section sample, taking into account aggregates size. The features that have been captured and quantified using 2-D images were limited to aggregates size. The elaborated algorithm and its implementation are presented. The tool is prepared as a part of a bigger system dedicated to road pavement analysis.