Highway Pavement Research Articles

Key pavement condition indicators for assessing highway pavement maintenance quality index

The technical condition of road pavements requires regular monitoring to support accurate maintenance decisions. However, existing pavement maintenance quality index (PQI) assessment methods are often expensive and infrequent, which limits intelligent decision-making. This paper proposes a cost-effective and precise PQI assessment method using data from five highways in Beijing. Key PQI indicators were identified through a hybrid feature selection method, and a CatBoost model optimised by a genetic algorithm (GA-CatBoost) was developed. The model demonstrated superior accuracy, achieving an R2 of 0.938, an MSE of 0.838, and an MAE of 0.576. It achieved 98.46% accuracy compared to traditional methods, confirming its reliability in an on-site application. This approach offers an economical solution for high-frequency PQI assessment, enabling intelligent decision-making in road infrastructure maintenance and supporting the use of lightweight detection equipment.

Performance Study of Stabilized Recycled Aggregate Base Material with Two-Gray Components.

This article studies the practical road performance of recycled materials from construction waste, relying on the paving test section of the supporting project for the Qingdao Cross-Sea Bridge. The research focuses on the construction technology and road performance of using recycled construction waste materials in urban road sub-base construction. Through indoor tests such as sieving and unconfined compressive strength tests, relevant technical indicators were obtained and analyzed. Additionally, periodic core sampling, compaction tests, and rebound deflection tests were conducted on-site according to relevant standards to thoroughly investigate the specific effects of using construction waste in practice and to analyze and evaluate the actual feasibility of the materials for road use. The results indicate that the particle gradation of the construction mix in the test section aligns well with the target gradation, and the dosage of the mixing agent meets the design requirements. The 7-day unconfined compressive strength already satisfied the technical requirements for heavy and extremely heavy traffic on highways as specified in the "Technical Specifications for Construction of Highway Pavement Subbase" (JTG/T F20-2015), with the 14-day strength generally reaching 7 MPa. Core sampling revealed good aggregate gradation, smooth and straight profiles, and the thickness and strength of all parts meet the specifications. The compaction levels met the testing requirements, the surface deflection values showed a decreasing trend, and the deformation resistance was good, consistent with the general development patterns of semi-rigid sub-bases.

Investigating the interfacial vertical shear behavior of BFPMPC mortar and cement concrete with pothole repair

Magnesium phosphate cement (MPC) has both traditional cement properties and ceramic properties with fast setting and hardening characteristics. To rapidly reopen traffic and extend its service life, MPC has been widely used in the rapid repair of highway and airport cement concrete pavement. This study utilizes basalt fiber-reinforced polymer-modified magnesium phosphate cement (BFPMPC) developed in previous research to rapid repair the typical potholes on cement concrete pavement, aims to reveal the interface properties between BFPMPC mortar and cement concrete and further investigate the underlying mechanisms for such properties. Firstly, the optimal mixture ratio was determined by orthogonal test design. Then, the shear strength of the repair interface was measured by composite BFPMPC mortar and cement concrete specimens. The mechanical characteristics of the repair interface and the microscopic mechanism were characterized by nano-indentation technology and SEM/EDS. Finally, the interface constitutive model was established by DIGIMAT and finite element model was developed to simulate the interface failure. Results showed that the no new hydration products were produced by the addition of polymer in BFPMPC. BFPMPC matrix became denser with the increase of age, resulting in the better bonding between fiber and paste. The interface vertical shear strength at 6 h and 3 d were 3.1 MPa and 3.9 MPa, respectively. SEM/EDS results showed that polymer has a certain self-healing ability to decrease the crack width with increase of curing age, and a variety of inclusions in the repair interface were observed. The elastic modulus of each inclusion phase can be effectively analyzed by nanoindentation. The simulation results showed that the pressure on upper surface of BFPMPC mortar transfers to the bottom through the repair interface. As the tensile stress on the bottom over the maximum interface tensile stress, the cracks were extend from the bottom to upper, then the structure was failed. Interface vertical shear strength of numerical simulation was, respectively, 3.149 MPa and 3.957 MPa. It is close to the plain shear strength experimental value, validating the proposed interface constitutive relationship.

Підвищення колієстійкастосування армуючих синтетичнихості та довговічності асфальтобетонних покривів на автомобільних дорогах і автодорожніх мостах з допомогою з матеріалів ADFORS GLASGRID

Introduction. One of the most common defects in the asphalt concrete pavements of highways and highway bridges that arise during their operation is the formation of ruts. The problem of increasing the rut resistance and durability of asphalt concrete pavements of highways, city streets and roads, at intersections, in front of traffic light intersections, at public transport stops and on the right lanes of bridges and overpasses is very relevant all over the world. One of the effective means of solving this problem is to increase the rut resistance and durability of asphalt concrete pavements by reinforcing them with Adfors GlasGrid® reinforcing synthetic materials.

Development of Risk-Based Methodologies for Highway Pavement Construction Inspection

Construction inspection plays a critical role in Portland cement concrete pavement (PCCP) and hot mix asphalt (HMA) pavement projects. To ensure the quality of pavement projects, state departments of transportation (DOTs) in the U.S. typically conduct construction material tests and inspect workmanship processes using quality assurance (QA) programs. Given today’s reality of reduced QA inspection resources such as funding, staff ability, and availability, several state DOTs have used a risk-based inspection (RBI) approach to optimize their QA processes. A thorough review of existing literature revealed limited studies examining RBI methodologies in highway pavement construction projects. The aim of this study is to investigate the use of RBI for pavement construction projects. It employed a triangulation research methodology, including an extensive literature review, a survey questionnaire of 50 state DOTs, focus groups, and a vetting workshop. A list of 16 core items in field inspection for both PCCP and HMA pavement projects was developed and verified. A generic risk rating of these critical inspection activities was determined. Additionally, inspection frequency, documentation effort, and inspector experience associated with these critical inspection activities identified through focus groups and the vetting workshop served as a reference point when conducting RBI for PCCP and HMA pavement projects. This study contributes to the body of knowledge and the highway construction industry by identifying and prioritizing 16 core inspection items for PCCP and HMA pavement construction. Construction project managers and inspectors may benefit from this study by analyzing the risks of core inspection items and implementing appropriate risk mitigation plans.

Analysis of the mechanical behavior of asphalt pavement under multiple coupling effects

To reveal the damage mechanism of asphalt pavement caused by the spatial rotation of the stress principal axis, and the influence range of excess pore water pressure on the pavement under the coupling action of multiple fields, the finite element software was used to build the three-dimensional highway asphalt pavement models. Under the consideration of gravity's impact on dynamic computation results, the study investigated the variation patterns of the direction cosines of the principal stress axes of asphalt structural pavement elements under the action of moving loads, as well as the distribution laws of excess pore water pressure. The results indicate that the influence of gravity on dynamic computation results increases gradually with the depth of the pavement, reaching an error of first principal stress of 40.1 % at the bottom of the lower layer. During the movement of loads, the pavement elements directly under the load undergo rotation of the principal stress axes in the xy, xz, and yz planes under different physical fields. With increasing pavement depth, the angle between the first principal stress and the z-axis primarily fluctuates between −90° to 0° and 90° to 180°. The cosine of the angle between the first principal stress and the x-axis and z-axis undergoes instantaneous positive and negative conversion, which can easily lead to transverse and longitudinal cracks on the road surface. The influence widths of excess pore water pressure along the longitudinal and transverse directions of the pavement increase with the pavement depth, with maximum widths of 5.426 m and 2.075 m, respectively. These findings offer new insights into the mechanisms behind the formation of transverse and longitudinal cracks on asphalt pavement and hold significant implications for the improvement of asphalt design methods.

UPDAPS-Flood: a mechanistic-empirical flexible pavement analysis tool to evaluate the effect of flooding events on flexible pavement performance

ABSTRACT Flooding can cause considerable damage to flexible pavements and negatively affects their performance over time. This study aims to evaluate the flooding effects on the flexible pavement performance and the potential resiliency of the pavement network through a mechanistic-empirical (ME) pavement analysis approach. The Unified Pavement Distress Analysis and Prediction System (UPDAPS) programme, which includes ME analysis models, was used to develop the UPDAPS-Flood programme. A total of 7,655 flexible pavement sections were extracted from the Highway Pavement Management System (HPMS) database in three United States regions. Finally, the resiliency of the pavement network to flood events was quantified using the loss of pavement service life based on the international roughness index (IRI). The results showed that flooding has the highest impact on rutting performance, followed by IRI and fatigue cracking. It has been found that a proper drainage system can reduce the flooding impact by a factor of two. The predicted pavement performance was found to be very sensitive to the coefficients of the rutting model, which brings the need for further studies to re-calibrate the rutting prediction model at higher moisture content levels.

Evaluation of the performance of warm asphalt mixture with Sasobit

Abstract The highway pavement construction industry has consistently attempted to promote the use of warm-mix asphalt (WMA) to encourage the construction of environmentally friendly pavement. This study aims to investigate the mechanical characteristics of warm asphalt mixtures that are made by utilizing modified asphalt binders containing different amounts of Sasobit. The base bitumen is modified with various percentages of Sasobit (3%, 4%, 5%, and 6%) of the weight of the bitumen by shear mixing. The rheological-physical characteristics of the base and enhanced asphalt binders were assessed using various tests such as: rotational-viscosity, softening point, and penetration tests. The stiffness, susceptibility to moisture, and resistance to rutting of the hot and warm mixes, made the binders are modified by using Sasobit, were assessed through Marshall characteristics, tensile strength, and punching shear tests. The findings demonstrated a significant enhancement in the rheological-physical characteristics of the modified binders. Findings revealed that the asphalt mixtures containing 5% Sasobi-modified binders exhibited more excellent resistance to both moisture damage and rutting in comparison to the control mixture.

Impact Assessment of Mixing Conditions on Rubberized Asphalt Binder

Abstract The objective of this study was to enhance the efficiency of the approach employed for preparing asphalt binders modified with waste rubber nanomaterial. A high-shear mixer has been utilized, with revaluation rates of 3000, 4000, 5000, and 6000 rpm. In addition, a mixing time of 30 minutes was employed. Four different waste rubber nanomaterial dosages were used: 0.5%, 1%, 1.5 %, and 2% by weight of asphalt cement, respectively. The asphalt binder was heated to 140 °C. The characteristics of the modified asphalt binder, including penetration grade, softening point temperature, temperature sensitivity, rotational viscosity, and ductility, were analyzed. The study demonstrated that incorporating waste rubber nanomaterial as a modifier improved the physical characteristics of the asphalt binder. Overall, the study revealed decreased penetration and increased softening point temperature and viscosity values. Additionally, the temperature sensitivity was enhanced. In addition, high shear mixing proved to be more efficient in achieving a thorough dispersion of waste rubber nanomaterial particles within the asphalt binder, resulting in a uniform composite binder. The tested samples demonstrated that adding a dosage of 1 % waste rubber nanomaterial enhanced the physical characteristics of asphalt, making it more suitable for the construction of highway pavements in hot weather conditions.

Influence of Waste Rubber Nano-Material Utilization on The Engineering Properties of Asphalt Matrix

Abstract The highway pavement construction industry is widely recognized as the most suitable establishment for recycling waste materials. Consequently, selecting sustainable materials constitutes a crucial concept for developing an innovative pavement construction characteristic. This research investigation aims to explore the consequences of utilizing waste rubber nanomaterial as a sustainable supplementary at four various weight ratios (0.5, 1, 1.5, and 2) in bituminous material. The assessment involved physical features such as viscosity, ductility, penetration, penetration index, and softening point. A dry mixing process is also accomplished for modified asphalts by conducting a high shear mixer at 5000 rpm for 30 minutes at 160 °C was chosen to ensure optimal dispersion of the waste rubber nanomaterial. Overall, the results demonstrated that adding waste rubber nanomaterial increased viscosity and softening point temperature but decreased ductility and penetration. The enhanced penetration index values of the modified asphalts result from the incorporation of residual rubber nanomaterial. In contrast, the binder modified with 2% residual rubber nanomaterial and nano-rubberization exhibited a greater penetration index (PI); thus, it positively impacts the resistance to rutting failure.

Application of Automated Pavement Inspection Technology in Provincial Highway Pavement Maintenance Decision-Making

Taiwan’s provincial highways span approximately 5000 km and are crucial for connecting cities and towns. As pavement deteriorates over time and maintenance funds are limited, efficient pavement inspection and maintenance decision-making are challenging. Traditional inspections rely on manual visual assessments, consuming significant human resources and time without providing quantitative results. This study addresses current maintenance practices by introducing automated pavement damage detection technology to replace manual surveys. This technology significantly improves inspection efficiency and reduces costs. For example, traditional methods inspect 1 km per day, while automated survey vehicles cover 4 km per day, increasing efficiency fourfold. Additionally, automated surveys reduce inspection costs per kilometer by about 1.7 times, lowering long-term operational costs. Inspection results include the crack rate, rut depth, and roughness (IRI). Using K-means clustering analysis, maintenance thresholds for these indicators are established for decision-making. This method is applied to real cases and validated against actual maintenance decisions, showing that the introduced detection technology efficiently and objectively guides maintenance decisions and meets the needs of maintenance units. Finally, the inspection results are integrated into a pavement management platform, allowing direct maintenance decision-making and significantly enhancing management efficiency.

Stabilization of Krobokan Clay Soil with California Bearing Ratio (CBR) for Highway Pavement

In this research, clay soil will be stabilized in the Kerobokan Badung area by mixing the soil with various levels of lime. The problem to be solved is how much the CBR value of soil mixed with lime will increase and what is the most economical lime content associated with the minimum CBR requirements for the base soil layer. The aim is to determine the increase in CBR value from a mixture of clay with lime and to determine the most economical lime content associated with the minimum CBR requirements for the base layer of highway pavement structures. The research results show that adding lime to clay soil can increase its bearing capacity. For the standard compaction method, the CBR of the base soil which was initially 3.32% increased to 12.14, 21.86, and 26.24% for lime addition of 2.50, 5.00, and 10.00% respectively. For the modified compaction method, the CBR of the base soil which was initially 5.74% increased to 13.42, 25.69, and 38.15% for lime addition of 2.50, 5.00, and 10.00% respectively. To produce a base soil CBR of 6%, the modified compaction method requires less lime content than the standard method. The lime content required is 0.22% for modified compaction and 0.79% for standard compaction.

Mechanistic Pavement Modeling of Typical Brazilian Pavements: Cohesive Zone Fracture Modeling and Continuum Damage Modeling

Pavement performance evaluation with respect to fatigue cracking has seen a major shift toward more rigorous mechanistic models that can capture the complex damage response of the mixtures more accurately. This study utilized two mechanistic methods (cohesive zone [CZ]-based fracture modeling and continuum damage [CD] modeling) to study the cracking behavior of asphalt mixtures and subsequently predict the damage-associated performance of pavements. A Superpave mixture designed for Brazilian highway conditions was selected to evaluate the two modeling approaches for the performance of the mixture when utilized as a surface course within typical Brazilian highway pavements. The mixture was first evaluated for its linear viscoelastic properties, and then the damage characteristics of the mixture were obtained through two different experiments: the semi-circular bending (SCB) beam test and the cyclic fatigue (CF) test. The SCB tests performed at different loading rates were used to obtain the model parameters of the nonlinear viscoelastic CZ model with a Gaussian damage evolution criterion, while the CF tests were performed at different strain amplitudes, and the mixture-specific damage characteristic curve and the fatigue failure criterion were obtained using the simplified-viscoelastic continuum damage model. From a design perspective, three pavement structures that varied in geometry (pavement layer thickness) and underlying layer properties were selected while retaining the same asphalt mixture. The three pavement scenarios were evaluated for the fatigue cracking performance from each of the mechanistic modeling methods. The results indicate that both methods rank the performance of the pavement structures in a similar manner, while the damage initiation and progression were seen to be different because of the different mechanics in modeling cracks.

Performance Assessment of Existing Asphalt Pavement in China’s Highway Reconstruction and Expansion Project Based on Coupling Weighting Method and Cloud Model Theory

In China, a substantial portion of highway asphalt pavements are no longer capable of accommodating increasing traffic volumes and necessitate renovation and expansion. Prior to commencing such activities, it is crucial to evaluate the performance of the existing asphalt pavements. This study developed a novel normal cloud framework integrating a comprehensive weighted indicator system for existing asphalt pavement. Five key performance indicators including riding quality index (RQI), rutting area ratio (Rr), cracking area ratio (Cr), patching area ratio (Pr), and pavement structural strength index (PSSI) were selected to holistically represent the pavement condition in highway renovation and expansion projects. Subsequently, a method was proposed to determine the weights of these indicators by integrating the analytic hierarchy process (AHP) and entropy. A normal cloud model was constructed to address data characteristics and representation of indicator fuzziness/randomness through digital cloud modeling. The model was applied to 12 sections of the Jingjintang Expressway (Tianjin section). The results revealed only one section where the normal cloud model differed from the pavement maintenance quality assessment (PQI) model. The 3D ground-penetrating radar detection results of this different section indicated that the normal cloud model more closely aligned with the road structure condition. Compared to absolute pass/fail criteria of the traditional PQI model, the cloud model offered enhanced sensitivity to define graded condition assessments essential for reconstruction planning and decision analysis. Therefore, the normal cloud model is more suitable for assessing the performance of existing asphalt pavements in highway reconstruction and extension projects compared to the PQI model.

A method to detect uniformity of road base course based on impact imaging technology

The damage of road base course has the characteristics of strong concealment and difficulty in detecting. For this reason, the impact imaging method has been used for detection of road base course. This paper discussed systematically collection points setting, excitation mode and data processing method. Through the application in testing for highway pavement base before and after grouting maintenance, the results show that the method is simple and accurate. The detection results can be displayed in a two-dimensional image form and it is easy to be used in road maintenance. This method can be used to identify and locate the damages of the pavement base, to judge the uniformity of the pavement base structure. It can also be used to evaluate the effectiveness of internal damage after grouting repairing.

Impacts of heavy-duty electric trucks on flexible pavements

ABSTRACT The transportation sector is responsible for significant greenhouse gas (GHG) emissions, with medium- and heavy-duty trucks (MHDTs) being major contributors. In response, medium- and heavy-duty electric trucks (MHDETs) are being explored as zero-emission alternatives. However, the weight of high-capacity batteries needed for long-haul trips and heavy loads could increase the axle loads as well as the gross vehicle weight (GVW) of heavy-duty electric trucks (HDETs), leading to extra damage on flexible highway pavements. This study simulated the GVW increment of HDETs and assessed its effects on pavement damage, environmental impacts, and life-cycle costs of four typical highway pavement structures in Illinois (known as thick–weak, thick–strong, thin–weak, and thin–strong). The utilisation of electric trucks resulted in significant reductions in diesel combustion related global warming potential (GWP) emissions and costs (in $2022) by 73% and 11.5%, respectively. However, the results demonstrated that with a 100% penetration of HDETs carrying an additional weight of 8 kips per truck, the pavement deterioration accelerated compared to traffic with conventional trucks. As a consequence, GWP and costs were reduced by 69% and 10.6%, respectively.

Calculated purpose of the distance between the expansion joints of cement concrete pavements of roads

Problem. The article discusses current issues of increasing the efficiency and quality of construction of cement concrete pavements for highways. It is shown that the regulatory documents in force in Ukraine recommend reducing the distances between compression joints and expansion joints during the construction of roads made of cement concrete. However, such a reduction leads to a slowdown in the pace of road construction and a significant increase in construction costs. The increase in cost occurs due to frequent stoppages of a set of concrete-laying machines and the formation of a large amount of concrete waste. The cost of this waste can reach UAH 200 thousand per 1 kilometer of road. In addition, frequent stops of a set of machines when laying cement concrete pavements of highways slow down the time it takes to put roads into operation. Purpose of the work. The aim is to calculate the expansion of cement concrete pavement when heated under operating conditions. Methodology. The work used formulas for thermophysical calculations during thermal expansion of concrete. The paper presents the results of thermophysical calculations of the expansion of cement concrete pavements of highways during their operation at elevated temperatures. It has been shown that when there are a large number of compression joints, they can partially compensate for the space required for concrete expansion. At the same time, they can act as compression joints during low temperatures. A design of double expansion seams has been proposed, which allows increasing the distance between them. The joint work of compression and expansion seams makes it possible to increase the distance between expansion seams. Due to this, it is possible to reduce their number, while simultaneously increasing the speed of construction and maintaining the quality indicators of the coating concrete. Originality: The article presents the results of a production test of thermophysical calculations. It is shown that two experimental sections of road surfaces were built. The concept of the maximum value of thermal expansion of concrete was further developed. Practical value: On one of them, the distance between expansion joints was 101 m, and on the other – about 300 meters. In this case, the distance between the expansion joints in the double seam was 1.5 meters. These parameters were sufficient for efficient and high-quality operation of double expansion joints.

A multi‐agent reinforcement learning model for maintenance optimization of interdependent highway pavement networks

AbstractPavement segments are functionally interdependent under traffic equilibrium, leading to interdependent maintenance and rehabilitation (M&R) decisions for different segments, but it has not received significant attention in the pavement management community yet. This study developed a maintenance optimization model for interdependent pavement networks based on the simultaneous network optimization (SNO) framework and a multi‐agent reinforcement learning algorithm. The established model was demonstrated on a highway pavement network in the real‐world, compared to a previously built two‐stage bottom‐up (TSBU) model. The results showed that, compared to TSBU, SNO produced a 3.0% reduction in total costs and an average pavement performance improvement of up to 17.5%. It prefers concentrated M&R schedules and tends to take more frequent preventive maintenance to reduce costly rehabilitation. The results of this research are anticipated to provide practitioners with quantitative estimates of the possible impact of ignoring segment interdependencies in M&R planning.

Theoretical substantiation of system for organising preventive treatment of asphalt concrete road pavements

Introduction. Over the past 20 years, the fleet of vehicles in the Republic of Belarus has increased significantly, and, consequently, the intensity of traffic on roads with a proportional increase in wear and tear of their surfaces. The need to protect asphalt concrete pavements from premature destruction dictates the search for new technological solutions. To effectively protect asphalt concrete pavements from the complex effects of water and traffic loads in the autumn-winter and spring-winter periods, the author has developed and implemented one of the options for protecting asphalt concrete pavements of a highway – treating them with a hydrophobic preventive Protekt- 01composition.Materials and methods. The research used theoretical and practical results from the implementation of the developed hydrophobic prophylactic composition.Results. The article presents an overview of the state of the problem of preventing destruction of asphalt concrete pavements abroad and in the Republic of Belarus, an analysis of the measures taken to implement the developed hydrophobic preventive Protekt-01composition at transport infrastructure facilities, and also, based on the data obtained from production testing a ‘System for organizing preventive treatment’ has been proposed, which will be aimed at preventing the beginning and future destruction of the asphalt concrete pavement of highways and will be based on monitoring the technical condition of the control object, planning, organizing, implementing and managing preventive and repair measures using navigation equipment and software that makes it possible to optimize the balance of costs and road surface defects.Originality. Thus, based on the theoretical substantiation and the results of practical implementation of the developed composition, the following are proposed:- method for ensuring the operation of a control system for liquid road-building materials which enables to eliminate overconsumption of the distributed substance;- ‘System for organizing preventive treatment’, which enables to increase the service life of asphalt concrete pavement by 1.2–1.5 times.

An appraisal of statistical and probabilistic models in highway pavements

Accurate performance prediction is crucial for safe and efficient travel on highway pavements. Within pavement engineering, statistical models play a pivotal role in understanding pavement behavior and durability. This comprehensive study critically evaluates a spectrum of statistical models utilized in pavement engineering, encompassing mechanistic-empirical, Weibull distribution, Markov chain, regression, Bayesian networks, Monte Carlo simulation, artificial neural networks, support vector machines, random forest, decision tree, fuzzy logic, time series analysis, stochastic differential equations, copula, hidden semi-Markov, generalized linear, survival analysis, response surface methodology and extreme value theory models. The assessment meticulously examines equations, parameters, data prerequisites, advantages, limitations, and applicability of each model. Detailed discussions delve into the significance of equations and parameters, evaluating model performance in predicting pavement distress, performance assessment, design optimization, and life-cycle cost analysis. Key findings emphasize the critical aspects of accurate input parameters, calibration, validation, data availability, and model complexity. Strengths, limitations, and applicability across various pavement types, materials, and climate conditions are meticulously highlighted for each model. Recommendations are outlined to enhance the effectiveness of statistical models in pavement engineering. These suggestions encompass further research and development, standardized data collection, calibration and validation protocols, model integration, decision-making frameworks, collaborative efforts, and ongoing model evaluation. Implementing these recommendations is anticipated to enhance prediction accuracy and enable informed decision-making throughout highway pavement design, construction, maintenance, and management. This study is anticipated to serve as a valuable resource, providing guidance and insights for researchers, practitioners, and stakeholders engaged in asphalt engineering, facilitating the effective utilization of statistical models in real-world pavement projects.