Bridge expansion joint in road transition curve: effects assessment on heavy vehicles

Properly-designed road surfaces provide a durable surface on which traffic can pass smoothly and safely. In fact, the main causes that determine the structural decay of the pavement and its parts are the traffic loads. These repeated actions can create undesirable unevennesses on the road surface, which induce vertical accelerations on vehicles, up to hindering contact between pavement and tire, with dangerous consequences on traffic safety. The dynamic actions transmitted by the vehicles depend on these irregularities: often, a bridge expansion joint (BEJ), introducing a necessary discontinuity between different materials, determines from the beginning a geometric irregularity in the running surface. Besides, some structural conditions could emphasize the problem (e.g., local cracking due to the settlement of the subgrade near the abutment or the discontinuity of stiffness due to the presence of different materials). When the BEJ is located in a transition curve, an inevitable vertical irregularity between road and joint can reach values of some centimeters, with serious consequences for the road safety. This paper deals with the analysis of a case study of a BEJ. Several test surveys were performed in order to fully characterize the effects on both vehicles and pavement. The three-dimensional representation of the pavement surface and the acceleration measurements on a heavy test vehicle were performed to analyze the joint behavior under traffic. Finally, a finite element model was implemented to evaluate the stress contribution on vehicle components induced by the vertical irregularities

Sampietrini stone pavements: Distress analysis using pavement condition index method

In several Italian cities, it is possible to find historical pavements such as the Sampietrini pavements, which are mainly located in the center of the city of Rome. The Sampietrini pavement is a particular road surface paved in natural stone with irregular sharp elements that are assembled by hand with the evident not plan effect. Because of their peculiarities, they are not suitable for streets where high speed is allowed. In many cases, high vibration and noise levels due to road traffic traveling on Sampietrini pavements are caused by inadequate maintenance, which is also affected by the absence of specific evaluation criteria regarding surface conditions and performances of Sampietrini pavements. It is not possible, in fact, to adopt common approaches developed to be used for flexible and rigid pavements, because they present completely different features and distresses. In this paper, to overpass this problem, a new evaluation criterion based on Pavement Condition Index (PCI) method established for block pavements is proposed. Furthermore, to fully characterize this kind of pavements, other analyses, i.e., International Roughness Index (IRI) and comfort level evaluation based on ISO 2631 standard, were also carried out. The results showed a good correlation between PCI and IRI approaches (R 2 = 0.82), also highlighting that new or reconstructed Sampietrini pavements present not negligible roughness level. This aspect was also confirmed estimating the comfort level perceived by users traveling at several speeds (≤50 km/h). Finally, speed related threshold values to be adopted for PCI and IRI methods are proposed. The proposed method can be implemented by pavement managers in a PMS ad hoc for stone block paving and thus, it can be integrated with other equivalents methods of visual inspection based on PCI

Ride quality due to road surface irregularities: Comparison of different methods applied on a set of real road profiles

Road roughness evaluation can be carried out using different approaches. Among these, the assessment of ride quality level perceived by road users is one of the most-used. In this sense, different evaluation methods have been developed in order to link the level of irregularities present on road surface profiles with the induced detrimental effects in terms of discomfort. In particular, relationships between wavelength content of road profiles and consequent level of comfort perceived had been investigated by using, in general, a mean panel ratings approach. In this paper, four ride quality evaluation methods (Ride Number, Michigan Ride Quality Index (RQI), Minnesota Ride Quality Index and frequency-weighted vertical acceleration, awz, according to ISO 2631 were applied to a set of real road profiles. The obtained results were analyzed, investigating a possible relation between the different indices, comparing them also with the most-used road roughness method worldwide: the International Roughness Index (IRI). The analyses carried out in this work have highlighted how the various rating scales may lead to a different ride quality assessment of the same road pavements. Furthermore, comparing the awz with the values obtained for the other three methods, it was found that their rating scales are set for speeds within the range 80–100 km/h. For this reason, it is necessary to identify new thresholds to be applied for lower speeds, as in the case of urban roads. In this sense, the use of the ISO 2631 approach would seem to be a useful tool

Variability of gravel pavement roughness: an analysis of the impact on vehicle dynamic response and driving comfort

Gravel pavement has lower construction costs but poorer performance than asphalt surfaces on roads. It also emits dust and deforms under the impact of vehicle loads and ambient air factors; the resulting ripples and ruts constantly deepen, and therefore increase vehicle vibrations and fuel consumption, and reduce safe driving speed and comfort. In this study, existing pavement quality evaluation indexes are analysed, and a methodology for adapting them for roads with gravel pavement is proposed. We report the measured wave depth and length of gravel pavement profile using the straightedge method on a 160 m long road section at three stages of road utilization. The measured pavement elevation was processed according to ISO 8608, and the frequency response of a vehicle was investigated using simulations in MATLAB/Simulink. The international roughness index (IRI) analysis showed that a speed of 30-45 km/h instead of 80 km/h provided the objective results of the IRI calculation on the flexible pavement due to the decreasing velocity of a vehicle’s unsprung mass on a more deteriorated road pavement state. The influence of the corrugation phenomenon of gravel pavement was explored, identifying specific driving safety and comfort cases. Finally, an increase in the dynamic load coefficient (DLC) at a low speed of 30 km/h on the most deteriorated pavement and a high speed of 90 km/h on the middle-quality pavement demonstrated the demand for timely gravel pavement maintenance and the complicated prediction of a safe driving speed for drivers. The main relevant objectives of this study are the adaptation of a road roughness indicator to gravel pavement, including the evaluation of vehicle dynamic responses at different speeds and pavement deterioration states

A Mathematical Model to Evaluate the Impact of the Maintenance Strategy on the Service Life of Flexible Pavements

[Abstract] The structural failure of a flexible pavement occurs when the accumulated fatigue damage produced by all the vehicles that have passed over each section exceeds a certain threshold. For this reason, the service life of pavement can be predicted in terms of the damage caused by the passage of a single standard axle and the expected evolution of traffic intensity (measured in equivalent standard axles) over time. In turn, the damage caused by the passage of an axle depends on the vertical load exerted by the wheels on the pavement surface, as given by the technical standard in application, and the depths and mechanical characteristics of the layers that compose the pavement section. In all standards currently in application, the unevenness of the road surface is disregarded. Therefore, no dynamic effects are taken into consideration and the vertical load is simply given in terms of the static weight carried by the standard axle. However, it is obvious that the road profile deteriorates over time, and it has been shown that the increase in the pavement roughness, when considered, gives rise to important dynamic effects that may lead to a dramatic fall in the expected structural service life. In this paper, we present a mathematical formulation for the fatigue analysis of flexible pavements that includes the effects of dynamic axle loading. A pavement deterioration model simulates the sustained growth of the IRI (International Roughness Index) over time. Time is discretized in successive time steps. For each time step, a road surface generation model provides a profile that renders the adequate value of the IRI. A QHV (Quarter Heavy Vehicle) model provides the dynamic amplification function for the loads exerted on the road surface along a virtual ride. This function is conveniently averaged, what gives the value of the so-called effective dynamic load amplification factor (DLA); this is the ratio between the effective dynamic loading and the static loading at each time step. Finally, the damage caused by the passage of the standard axle can be evaluated in terms of the dynamic loading. The product of this damage times the number of equivalent standard axles gives the total fatigue damage produced in the time step. The accumulated fatigue damage at each moment is easily computed by just adding up the damage produced in all the previous time steps. The formulation has been implemented in the software DMSA (Dynamic & Maintenance Simulation App). This tool has been specifically developed for the evaluation of projects in applications for financing submitted to the European Investment Bank (EIB). DMSA allows for quantifying the expected structural service life of the pavement taking into account both the rise of the dynamic axle loads exerted by the traffic as the road profile deteriorates over time and the different preventive maintenance strategies to be taken into consideration.Ministerio de Economía y Competitividad; DPI2015-68431-RXunta de Galicia; GRC2014/03

Impact of Dynamic Axle Loading on the Service Life of Flexible Pavements

Programa Oficial de Doutoramento en Enxeñaría Civil . 5011V01[Abstract] Impact of dynamic axle loading on the service life of flexible pavements The study of pavement maintenance strategies has gained great importance in recent years, both because of the drastic decrease in investments for the maintenance of road infrastructures and because of the benefits associated with the performance of such preventive maintenance. This doctoral thesis uses a methodology focused on the study of the impact of preventive maintenance strategies on the service life of flexible pavements, taking into account the effect of dynamic rolling loads. The first part of the methodology focuses on calculating the fatigue failure of a flexible pavement considering the effect of dynamic axle loads. For this purpose, a multilayer elastic model is first developed to calculate the mechanical responses of the firm. Then, a structural failure model of the pavement and its fatigue failure criteria are defined. The second part of the methodology focuses on the role of dynamic axle loads in the fatigue failure of the pavement. First, the methodology for calculating these dynamic axle loads using a quarter heavy vehicle model is presented, which requires the computational simulation of a longitudinal road profile. Finally, a deterioration model of surface evenness is presented, thanks to which it is possible to simulate the time evolution of this surface evenness, and therefore, the time evolution of the dynamic axle loads during the pavement service life. Finally, the algorithm used is presented, as well as the reduced model of this algorithm and its implementation in a software that allows to calculate the effect of different preventive maintenance strategies on the service life of a flexible pavement.[Resumen] Impacto de las cargas dinámicas en la vida útil de firmes flexibles El estudio de las estrategias de conservación de firmes ha cobrado gran importancia en los últimos años, tanto por el descenso drástico en las inversiones para el mantenimiento de las infraestructuras viarias como por los beneficios asociados a la realización de dicho mantenimiento preventivo. En la presente tesis doctoral se desarrolla una metodología centrada en el estudio del impacto sobre la vida útil de firmes flexibles de las estrategias de mantenimiento preventivo, teniendo en cuenta el efecto de las cargas dinámicas de rodadura. La primera parte de la metodología empleada se centra en calcular el fallo a fatiga de un firme flexible considerando el efecto de las cargas dinámicas de rodadura. Para dicho fin, primeramente se desarrolla un modelo elástico multicapa para calcular las respuestas mecánicas del paquete de firme. A continuación se define un modelo de comportamiento de dicho paquete de firme y su criterio de fallo por fatiga. La segunda parte de la metodología se centra en el papel que desempeñan las cargas dinámicas de rodadura en el fallo por fatiga del paquete de firme. En primer lugar se presenta la metodología para calcular dichas cargas dinámicas de rodadura empleando un modelo de cuarto de vehículo pesado, la cual requiere de la simulación computacional de un perfil longitudinal de carretera. Finalmente se presenta un modelo de deterioración de regularidad superficial, gracias al cual se puede simular la evolución temporal de dicha regularidad superficial, y por lo tanto, la evolución temporal de las cargas dinámicas de rodadura durante la vida ´útil del firme. Finalmente se presenta el algoritmo empleado, así como el modelo reducido de dicho algoritmo y su implementación en un software que permite calcular el efecto de diferentes estrategias de mantenimiento preventivo en la vida útil de un firme flexible.[Resumo] Impacto das cargas dinámicas na vida útil dos pavimentos flexíbeis O estudo das estratexias de conservación de firmes cobrou gran importancia nos últimos anos, tanto polo declive drástico nos investimentos para o mantemento das infrastructuras viarias coma polos beneficios asociados á realización de dito mantemento preventivo. Na presente tese doutoral lévasne a cabo unha metodoloxía centrada no estudo do impacto sobre a vida útil dos firmes flexíbeis das estratexias de mantemento preventivo, tendo en conta o efecto das cargas dinámicas de rodadura. A primeira parte da metodoloxía empregada céntrase en calcular o fallo a fatiga dun firme flexíbel considerando o efecto das cargas dinámicas de rodadura. Para dito fin, primeiramente desenvólvese un modelo elástico multicapa para calcular as respostas mecánicas do paquete de firme. Deseguido defínese un modelo de comportamento deste paquete de firme e o seu criterio de fallo por fatiga. A segunda parte da metodoloxía céntrase no papel que desempeñan as cargas dinámicas de rodadura no fallo por fatiga do paquete de firme. En primeiro lugar preséntase a metodoloxía para calcular ditas cargas dinámicas de rodadura empregando un modelo de cuarto de vehículo pesado, a cal require da simulación computacional dun perfil lonxitudinal de estrada. Finalmente preséntase un modelo de deterioración de regularidade superficial, grazas ao cal pódese simular a evolución temporal de dita regularidade superficial, e polo tanto, a evolución temporal das cargas dinámicas de rodadura durante a vida útil do firme. Finalmente preséntase o algoritmo empregado, así como o modelo reducido deste algoritmo e a súa implementación nun software que permite calcular o efecto de diferentes estratexias de mantemento preventivo na vida útil dun firme flexíbel.This work has been primarily supported by the European Investment Bank (EIB) Institute through a STAREBEI grant awarded to the Fundaci´on de la Ingeniería Civil de Galicia. Partial support has also been provided by FEDER funds of the European Union, by the Ministerio de Economía y Competitividad of the Spanish Government through grant #DPI2015-68431-R, by the Ministerio de Ciencia, Innovación y Universidades of the Spanish Government through grant #RTI2018-093366-BI00, by the Secretaría Xeral de Universidades of the Xunta de Galicia through grants GRC2014/039 and # ED431C 2018/41, by the Conselleria de Cultura, Educación e Ordenación Universitaria of the Xunta de Galicia through a grant awarded to the University of A Coru˜na, and by research fellowships of the University of A Coruña and the Fundación de la Ingeniería Civil de Galicia.Xunta de Galicia; ED431C 2018/41Xunta de Galicia; GRC2014/03

Quantifying road roughness: multiresolution and near real-time analysis

Road roughness is a key parameter for road construction and for assessing ride quality during the life of paved and unpaved road systems. The quarter-car model (QC model), is a standard mathematical tool for estimating suspension responses and can be used for summative or pointwise analysis of vehicle response to road geometry. In fact, transportation agencies specify roughness requirements as summative values for pavement projects that affect construction practices and contractor pay factors. The International Roughness Index (IRI), a summative statistic of quarter-car suspension response, is widely used to characterize overall roughness profiles of pavement stretches but does not provide sufficient detail about the frequency or spatial distribution of roughness features. This research focuses on two pointwise approaches, continuous roughness maps and wavelets analysis, that both characterize overall roughness and identify localized features and compares these findings with IRI results. Automated algorithms were developed to preform finite difference analysis of point cloud data collected by three-dimensional (3D) stationary terrestrial laser scans of paved and unpaved roads. This resulted in continuous roughness maps that characterized both spatial roughness and localized features. However, to address the computational limitations of finite difference analysis, Fourier and wavelets (discrete and continuous wavelet transform) analyses were conducted on sample profiles from the federal highway administration (FHWA) Long Term Pavement Performance data base. The Fourier analysis was performed by transforming profiles into frequency domain and applying the QC filter to the transformed profile. The filtered profiles are transformed back to spatial domain to inspect the location of high amplitudes in the suspension rate profiles. Finite difference analysis provides suspension responses in spatial domain, on the other hand Fourier analysis can be performed in either frequency or spatial domains only. To describe the location and frequency content of localized features in a profile, wavelet filters were customized to separate the suspension response profiles into sub profiles with known frequency bands. Other advantages of wavelets analysis includes data compression, making inferences from compressed data, and analyzing short profiles (\u3c 7.6 m). The proposed approaches present the basis for developing real-time autonomous algorithms for smoothness based quality control and maintenance

Pavement Performance Evaluation Using Connected Vehicles

Roads deteriorate at different rates from weathering and use. Hence, transportation agencies must assess the ride quality of a facility regularly to determine its maintenance needs. Existing models to characterize ride quality produce the International Roughness Index (IRI), the prevailing summary of roughness. Nearly all state agencies use Inertial Profilers to produce the IRI. Such heavily instrumented vehicles require trained personnel for their operation and data interpretation. Resource constraints prevent the scaling of these existing methods beyond 4% of the network. This dissertation developed an alternative method to characterize ride quality that uses regular passenger vehicles. Smartphones or connected vehicles provide the onboard sensor data needed to enable the new technique. The new method provides a single index summary of ride quality for all paved and unpaved roads. The new index is directly proportional to the IRI. A new transform integrates sensor data streams from connected vehicles to produce a linear energy density representation of roughness. The ensemble average of indices from different speed ranges converges to a repeatable characterization of roughness. The currently used IRI is undefined at speeds other than 80 km/h. This constraint mischaracterizes roughness experienced at other speeds. The newly proposed transform integrates the average roughness indices from all speed ranges to produce a speed-independent characterization of ride quality. This property avoids spatial wavelength bias, which is a critical deficiency of the IRI. The new method leverages the emergence of connected vehicles to provide continuous characterizations of ride quality for the entire roadway network. This dissertation derived precision bounds of deterioration forecasting for models that could utilize the new index. The results demonstrated continuous performance improvements with additional vehicle participation. With practical traversal volumes, the achievable precision of forecast is within a few days. This work also quantified capabilities of the new transform to localize roadway anomalies that could pose travel hazards. The methods included derivations of the best sensor settings to achieve the desired performances. Several case studies validated the findings. These new techniques have the potential to save agencies millions of dollars annually by enabling predictive maintenance practices for all roadways, worldwide.Mountain Plains Consortium (MPC

Roughness-Induced Vehicle Energy Dissipation: Statistical Analysis and Scaling

The energy dissipated in a vehicle suspension system due to road roughness affects rolling resistance and the resulting fuel consumption and greenhouse gas emission. The key parameters driving this dissipation mechanism are identified via dimensional analysis. A mechanistic model is proposed that relates vehicle dynamic properties and road roughness statistics to vehicle dissipated energy and thus fuel consumption. A scaling relationship between the dissipated energy and the most commonly used road roughness index, the International Roughness Index (IRI), is also established. It is shown that the dissipated energy scales with IRI squared and scaling of dissipation with vehicle speed V depends on road waviness number w in the form of V[superscript w−2]. The effect of marginal probability distribution of the road roughness profile on dissipated energy is examined. It is shown that although the marginal distribution of the road profile does not affect the identified scaling relationships, the multiplicative factor in these relationships does change from one distribution to another. As an example of practical application, the model is calibrated with the empirical HDM-4 model for different vehicle classes