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Bridge engineers increasingly prefer to use the Ground-Penetrating Radar (GPR) technique. GPR can yield data with very high spatial resolution, the data can be acquired rapidly and even during traffic, causing very low interferences. This paper presents a novel GPR system that is designed and developed for bridge applications. In addition it proposes a new algorithm for cracks tracking in a three-dimensional domain. The effectiveness and accuracy of the procedure have been calibrated and validated on four different bridges. In this paper, three-dimensional visualisations of cracks and two-dimensional tomographies and sections are shown to demonstrate the potentialities of the GPR system associated to the signal-processing algorithm.

Laboratory tests or measures on the field are widely carried out in order to evaluate the drainage capability of pavement. Such an approach is in general not efficient and it shows poor significance. In this paper The authors propose a novel method, very effective for mix design, based on simulation of unsteady-flow of water through open-graded mixture. In particular the authors have modelled internal microstructures of an open-graded asphalt sample, positioning any aggregate particle and creating the bitumen film around each of them. The unsteady-flow of water inside the sample is simulated to evaluate the expected permeability for different specimens and compaction.

Nowadays, severe meteorological events are always more frequent all over the world. This causes a strong impact on the environment such as numerous landslides, especially in rural areas. Rural roads are exposed to an increased risk for geotechnical instability. In the meantime, financial resources for maintenance are certainly decreased due to the international crisis and other different domestic factors. In this context, the best allocation of funds becomes a priority: efficiency and effectiveness of plans and actions are crucially requested. For this purpose, the correct localisation of geotechnically instable domains is strategic. In this paper, the use of Ground-Penetrating Radar (GPR) for geotechnical inspection of pavement and sub-pavement layers is proposed. A three-step protocol has been calibrated and validated to allocate efficiently and effectively the maintenance funds. In the first step, the instability is localised through an inspection at traffic speed using a 1-GHz GPR horn launched antenna. The productivity is generally about or over 300 Km/day. Data are processed offline by automatic procedures. In the second step, a GPR inspection restricted to the critical road sections is carried out using two coupled antennas. One antenna is used for top pavement inspection (1.6 GHz central frequency) and a second antenna (600 MHz central frequency) is used for sub-pavement structure diagnosis. Finally, GPR data are post-processed in the time and frequency domains to identify accurately the geometry of the instability. The case study shows the potentiality of this protocol applied to the rural roads exposed to a landslide.

"Recently the road networks are more and more exposed to an increased landslide risk. It is generally caused by heavy weather conditions and a severe deficit of maintenance. Usually, it is easy to locate the damage as it becomes visible whereas it is difficult to identify the causes. In order to diagnose the damage before it becomes visible and severe, to identify the main cause and to implement the most effective rehabilitation measure, we propose the use of Ground Penetrating Radar for geotechnical inspection of pavement and sub-pavement layers. Different equipments were used and a survey protocol was tested in several situations characterized by landslide movements with different degrees of severity. For the inspection, 600, 1000 and 1600 MHz antennae were used. The 1 GHz horn antenna was used for a first survey at traffic speed in order to reduce traffic interference and to locate any possible anomaly. The other dipole antennae were used for more detailed investigations. GPR data were post-processed in the time and frequency domain, using the “Surface reflection method” and the Rayleigh scattering. This approach provides an innovative method that can be applied for accurate and non-invasive monitoring of alert conditions near to road pavements."

The interdisciplinary project “SimWorld” - initiated by the German Aerospace Center (DLR) - aims to improve and to facilitate the generation of virtual landscapes for driving simulators. It integrates the expertise of different research institutes working in the field of car simulation and remote sensing technology. SimWorld will provide detailed virtual copies of the real world derived from air- and satellite-borne remote sensing data, using automated geo-scientific analysis techniques for more efficiency and greater realism for landscape models. The implementation of geo-databases and GIS technology within the simulator will allow for further simulation and testing of new technologies like e.g. radar-sensors, night vision systems as well as positioning systems such as GPS and Galileo.

The problem of slope stability has been studied for many decades, but the contribution of vegetation to stability has typically been treated empirically. In this paper the author proposes to include a rational model for the role of vegetation in a global computer simulation to evaluate stability. Vegetation can perform an important engineering function because of its influence on the soil, both in terms of hydrological and mechanical aspects. Here two advanced numerical models are coupled, one for the hydrological simulation of soil wetting and drying and one for geotechnical simulation of the slope stability. The simulation of a railway embankment has been carried out, and effects of different vegetation properties on stability investigated. This approach is very flexible, efficient and effective to postulate the expected Factor of Safety of a critical slip surface.

Ground Penetrating Radar is frequently used for inspection the road pavement. Many applications are carried out: from pavement's layer thickness estimation, to damage detection and diagnosis, from the evaluation of geotextile effectiveness to the assessment of the bridge decks. Here we propose to integrate GPR survey with the Light Falling Weight Deflectometer. LFWD is a portable instrument that is used for measuring the Young Modulus through the analysis of the propagation of elastic waves in the pavement structure. The point of strength of this approach is that it is possible to correlate geometrical and some physical characteristics, in this case dielectric constant, of pavement layers, extracted from the GPR maps, to the mechanical properties, such as young modulus, measured using LFWD. It is well known that from a GPR stand alone survey is not possible to have directly any information about the mechanical characteristics of the structure. Otherwise, following this integrated method it is possible to reach a more comprehensive description of the road pavement. This diagnostic tool for pavement damage investigations seems absolutely very promising, cost effective and efficient in its implementation. Finally two case studies are presented: the first over about 3000 m of a real pavement the second over an unpaved airport strip.

The overall objective of this study is the calibration of an eye tracking system for assessing the effectiveness and efficiency of different Variable Message Signs. The study has been carried out in the driving simulation laboratory of the Inter-Universities Research Centre for Road Safety (Italy). The first step of the research was the evaluation of the reliability of the eye tracking system. Twenty subjects have been tested in the laboratory. They were required to look at a point on a flat screen sitting in the simulator cabinet. The position of the point changes nine times on the screen each five seconds. The system tracks automatically the point focused by the subject. For each position the software takes more than hundred frames (frequency greater than 20 Hz). The positions focused by the subject are collected in a file that is post processed. The statistics of the residuals between point positions and focused positions show that the system is very accurate and the standard deviation is negligible considering the objective of the study. The second step of the research was the validation of ten different Variable Message Signs. The Signs are always composed with a pictogram and some words, symbols or numbers. The twenty subjects were required to look the signs for five seconds sitting in the driving simulator cabinet. During the test, the subjects were interviewed about the meaning and comprehension of each sign. A cross correlation between the interview outcomes and the eye tracks demonstrates that as the sign comprehension increases the eye fixes for about the same duration alternatively the pictogram and the words message. Otherwise the eye fixes for a longer time what it is unclear. In conclusion the study puts in light as the eye tracking system integrated in a driving simulator is a promising tool for in depth human factors analysis.

"The technique of soil stabilization is usually adopted with the purpose of rendering plastic soils coherent to the standards and requirements of engineering projects. The environmental benefits of soil stabilization versus the use of traditional natural material from quarries are generally underestimated. The case study of one significant section of the Italian High Speed Railway is presented here. This section is a part of the line from Milan to Venice. The volume of material that is needed for the development of embankments amounts to about 3 million m3 and 1.5 millions m3 of aggregates are needed for concrete. At the same time the construction of foundations produces about 1 million m3 of soil: 350,000 m3 from foundations, 400,000 m3 from diaphragms and drilled piles and 70,000 m3 from helicoidal piles. The need to manage such a significant volume of soil suggests the need for the consideration of recycling the clay soil after lime stabilization. The technical compatibility is here verified. The total costs of all the actions derived from the Environmental Impact Assessment for environment protection is less than 8% of the savings produced by the stabilization of soil. It finally demonstrates that the question of non-renewable resource management, such as soil, is strategic also under an environmental protection perspective."

Basing on the recent outcomes of an investigation on the water content evaluation from processing the GPR signal in the frequency domain, an accurate model for the prediction of the frequency spectrum of the reflected GPR signal as the moisture content changes is proposed. This method uses an Artificial Neural Network approach. After the training, the ANN is reasonably able to predict the frequency spectrum for a water content in a specific soil (the error in the spectrum generation computed on a validation set, after 105 training epochs, is about or less than 10% for the same soil, if the ANN is used for all kinds of soil the error increases to about 15–20%). Of course this method can be inverted generating with the trained ANN a catalogue of different spectra for different values of the soil water moisture. Using this inverse approach it is possible to predict the water content of a specific soil just comparing the real current spectrum of the reflected GPR signal with the spectra of the catalogue. This method has been successfully tested on experimental data.

The evaluation of the water content of unsaturated soil is important for many applications, such as environmental engineering, agriculture and soil science. This study is applied to pavement engineering, but the proposed approach can be utilized in other applications as well. There are various techniques currently available which measure the soil moisture content and some of these techniques are non-intrusive. Herein, a new methodology is proposed that avoids several disadvantages of existing techniques. In this study, ground-coupled Ground Penetrating Radar (GPR) techniques are used to non-destructively monitor the volumetric water content. The signal is processed in the frequency domain; this method is based on Rayleigh scattering according to the Fresnel theory. The scattering produces a non-linear frequency modulation of the electromagnetic signal, where the modulation is a function of the water content. To test the proposed method, five different types of soil were wetted in laboratory under controlled conditions and the samples were analyzed using GPR. The GPR data were processed in the frequency domain, demonstrating a correlation between the shift of the frequency spectrum of the radar signal and the moisture content. The techniques also demonstrate the potential for detecting clay content in soils. This frequency domain approach gives an innovative method that can be applied for an accurate and non-invasive estimation of the water content of soils – particularly, in sub-asphalt aggregate layers – and assessing the bearing capacity and efficacy of the pavement drainage layers. The main benefit of this method is that no preventive calibration is needed.

A new methodology has been proposed to extract the hydraulic permittivity fields in sub-asphalt structural layers and soils from the moisture maps observed with GPR. It is effective at diagnosing the presence of clay or cohesive soil that compromises the bearing capacity of sub-base and induces damage on the road. The numerical algorithm has been yet discussed in the 11th International Conference on Ground Penetrating Radar [5]. Here some experimental confirms have been presented.

Ground penetrating radar (GPR) signal processing is a nondestructive technique, currently performed by many agencies involved in road management and particularly promising for soil characteristics interpretation. The focus of this paper is to assess the reliability of an optimal signal processing algorithm for pavement inspection. Preliminary detection and subsequent classification of pavement damages, based on an automatic GPR analysis, have been performed and experimentally validated. A threshold analysis of the error is carried out to detect possible damages and check if they can be predicted, while a second threshold analysis determines the nature of the damage. An optimum detection procedure is performed. It implements the classical Neyman-Pearson radar test. All the settings needed by the procedure have been estimated from training sets of experimental measures. The overall performance has been evaluated by looking at the usual receiver's operating characteristic. The results show that a reasonable performance has been achieved by exploiting the spatial correlation properties of the received signal, obtained from an appropriate analysis of GPR images. The proposed system shows that automatic evaluation of subgrade soil characteristics by GPR-based signal analysis and processing can be considered reliable in a number of experimental cases.

We investigate the relation between the dielectric constant of soils and their volumetric water content to be used in non-invasive measures of water content, like Ground Penetrating Radar (GPR). After modeling the porous medium as a Multi Indicator structure, we derive the effective permittivity of the soil as function of the water content by adopting the effective medium approximation. The derived formula is tested against controlled, laboratory experiments. Citation: Fiori, A., A. Benedetto, and M. Romanelli (2005), Application of the effective medium approximation for determining water contents through GPR in coarse-grained soil materials

Ground Penetrating Radar based analysis of road pavement is actually performed by many agencies involved in road management. The radar image interpretation is the most difficult step for the resear...

An integrated methodology is proposed for the design of polluted water control systems for road infrastructures, based on hazard analysis concepts. The case of a simultaneous rainstorm and road accident with the dispersion of dangerous substances is considered. The risk function is computed with regard to the objective evaluation of severity of the event and to the stochastic calculation of the associate probability. A logical framework for the evaluation of severity is proposed by taking into consideration four possible circumstances for the dispersion of pollutants: surface and ground water, and natural and urban soil. A set of check lists have been devised for the assessment and design of the environmental protection control systems. The methodological approach is completed with the formulation of a stochastic model representing the statistical combination of the occurrence of the hydrological processes and the road accident dynamics. The stochastic model estimates the expected volume of contaminated r...

Ground penetrating radar (GPR) signal processing is a nondestructive technique, particularly promising for soil characteristics interpretation. In fact, pavement damage is actually one of the most crucial problems in roads. A preliminary detection and a subsequent classification of the pavement damage, based on an automatic GPR analysis, have been performed and experimentally validated. An optimum detection procedure is performed. It implements the classical Neyman-Pearson radar test. All the settings needed by the procedure have been estimated from a training set of measures. The overall performance has been evaluated by looking at the usual receiver's operating curve. The results evidence that a reasonable performance has been achieved by a suited analysis of GPR images exploiting the spatio-temporal correlation properties of the received signal. Although a generalization is not reliable, this study shows that an automatic GPR-based evaluation of subgrade soil characteristics is feasible.

An accurate and high-resolution description of the spatial variability of soil water content at the field scale and the distribution of water in the unsaturated zone requires a large number of measurements. Financial and time constraints limit the numbers of measurement locations; thus the standard approach for monitoring could lead to a large degree of uncertainty in spatial predictions. We test in a parcel of bare soil an alternative approach based on ground-based geophysical techniques, by comparing the monitoring of the soil water content obtained from the Electrical Resisitivity Imaging and the Ground Penetrating Radar with the variability maps estimated from the interpolation of soil water contents measured in different locations With capacitance probes. The agreement is good and the integration of the techniques is promising. (C) 2013 The Authors. Published by Elsevier B.V

This paper focuses on the studies and activities in the field of road safety and accident prediction carried out by the research group of the Department of Sciences of Civil Engineering Section Road Infrastructures. The group has been working on this topic since the eighties but only at the beginning of nineties the research activities reached meaningful results The new assumption formulated from the first investigations and demonstrated by the experimental studies declined the following criterion: traffic safety does not only involve kinetic and dynamical problems under the domain of road and mechanical engineering but also a multidisciplinary approach on the basis of the following assumptions: (1) traffic flow and mobility motivations influence risk thresholds and driving behaviours, (2) variability of environmental conditions affects safety standards, (3) human factors, perception reaction mechanism, decision making processes impact on driving manoeuvres and finally on safety. Traditional approaches have many points of weakness connected to the inadequacy of the accident database and to the low reliability of statistical methods for the diagnosis of the cause. Techniques based on artificial intelligence have been investigated. Neural networks are advanced mathematical models showing real and promising results, but their applicability is not easy and absolutely not efficient. Hazard analysis approach has given important, very applicable and reliable results.

Projecte realizat en col.laboració amb Università degli studi Roma Tre Without the right signal processing technique, the GPR tool would became useless. . With an appropiate algorithm we can exploit and use all the amout of data that the GPR provide us. Hence, the objective of the thesis is elaborate a signal processing algorithm in Matlab. This algorithm must be able to extract a synthetic map of the ground. This means that the algorithm has to calculate layer thickness and permitittivity of each layer that forms the pavement structure and draw the map colouring the different permitittivity areas. The algorithm should be fully configurable by the user depending on the particular zone to scan and, last but not least, it must be user-friendly.