Infrastructures

This research investigates the possibility of using high-density polyethylene (HDPE) plastic waste to improve the properties of asphalt concrete pavement. HDPE plastic waste contents of 1, 3, 5, and 7% by aggregate weight were used. HDPE plastic waste=stabilized asphalt concrete pavement (HDPE-ACP) was evaluated by performance testing for stability, indirect tensile strength, resilient modulus (MR), and indirect tensile fatigue (ITF). In addition, microstructure, pavement age, and CO₂ emissions savings analyses were conducted. The performance test results of the HDPE-ACP were better than those without HDPE plastic waste. The optimum HDPE plastic waste content was 5%, offering the maximum MR, ITF, and pavement age. Scanning electron microscope images showed that the excessive HDPE plastic waste content of 7% caused a surface rupture of the sample. Improvements in the pavement age of the HDPE-ACP samples were observed compared with the samples with no HDPE plastic waste. The highest pavement age of the HDPE-ACP sample was found at an HDPE plastic waste content of 5% by aggregate weight. The CO₂ emissions savings of the sample was 67.85 kg CO₂-e/m³ at the optimum HDPE plastic waste content. Full article

Value of time (VOT) is a crucial aspect of travel demand modeling. VOT impacts most mobility projects and the evaluations therein. It has been noted to be influenced by multiple factors, mainly related to individuals’ demographics and trips’ characteristics. This paper presents the results of a survey conducted among users of the Portuguese national freeway network, aiming to derive insights about their travel choice mechanism for testing mobility projects, in particular dynamic pricing strategies. Particular attention is dedicated to the value they attribute to travel time by analyzing willingness-to-pay for avoiding congestion and saving travel time. An elaborate questionnaire survey was distributed through online survey campaigns between March and June of 2021, eliciting 163 valid responses. Even after a stratification process, results revealed that VOT is generally lower than our original expectations; various statistical distributions were tested to fit the empirical data, the best performing ones were selected and the results were compared with a previous survey-based VOT study. We finally measured the elasticity of the freeway demand and of the whole demand for transportation, which confirmed the generally low willingness to pay for less congested travels. Full article

Progressing digitalization and networking of systems and organizations representing Critical Infrastructures opens promising new potentials and opportunities, which on the downside, are accompanied by rising complexity and increasingly opaque interdependencies. The consequently increasing lack of knowledge leads to uncertainties affecting risk assessment and decision-making in case of adverse events. This trend motivated recent discussions and developments in risk science, emphasizing the need to handle such uncertainties. Complementarily, research in the resilience domain focuses on system capabilities to handle surprising hazardous situations. Several frameworks presented in the literature aim at combining both perspectives but either lack the focus on operational management, have a rather theoretical approach, or are designed for specific applications. Based on this observation, we propose an approach that integrates resilience management into the actual operation of Critical Infrastructure Systems and Organizations by providing an operational process that coordinates the fundamental resilience capabilities of responding, monitoring, anticipation, and learning. Furthermore, we tackle the challenge of uncertainties resulting from a lack of knowledge by aligning the concepts of digital twin and resilience management. The proposed framework is extensively discussed, and required processes are presented in detail. Eventually, its applicability and potential are reviewed by means of a complex hazardous situation at a Bavarian district heating power plant. Full article

The electric tricycle, often known as an e-trike, is a three-wheeled electric vehicle designed to transport a small group of people over short distances on side streets. This study aims to develop a service quality model of sustainable e-trike operations in the city of Manila, Philippines using stepwise regression analysis. A total of 230 participants from three districts in the City of Manila: Binondo, Recto, and Intramuros, were selected using the stratified sampling method. The main contribution of this study emerges from the quantification of the influence of sustainability indicators on the perceived service quality of e-trike passengers. The study identified 10 indicators: PWD accessibility (β = 0.2128), smoothness of the ride (β = 0.1001), noise level (β = 0.0886), discount rate (β = 0.0886), land use (β = 0.0835), comfort load (β = 0.0723), fare acceptability (β = 0.0577), e-trike intensity (β = 0.0420), fare affordability (β = 0.0339), and ease of availability (β = 0.0317) have significant importance in the service quality of e-trike operations. These indicators revealed the areas where improvements are needed to ensure the long-term viability of e-trike operations. Therefore, it is concluded that these factors should be the focus and priority for the improvement of e-trike operators, drivers, and transport groups to attain sustainability of e-trike operation in the country. Moreover, this study can also be used for other public transportations to improve their current service quality and operations. Full article

Scour action is one of the main factors that add significant stress to the growing infrastructure crisis as it is considered one of the most destructive flood-related hazards occurring around underwater foundation elements. Recent cases of bridge failures have highlighted the need for a reliable scour monitoring and early warning system to assess flood and geo-hazards in real-time, providing advanced key info for repair and maintenance actions. Despite the past efforts to provide such a system for scour assessment, most of the developed instruments were not able to offer a reliable solution for scour monitoring, due to technical and cost issues. As a result, there currently exists a gap in the knowledge and understanding of scour mechanism during flood incidents. This study presents the development of a new sensing system to assess hydro-hazards at bridge infrastructure. It initially focuses on factors contributing to the growing infrastructure crisis and provides an overview of the current practices and assessment procedures to assess scour processes and a summary of advantages and limitations of existing monitoring efforts. A new monitoring concept for assessing scour and sediment deposition processes is then presented focusing on modelling the geometric components of a new sensor which is evaluated in simulations under different environments that represent prospective field conditions. Main results are analysed and presented focusing on key criteria that maximize sensitivity of the sensor to scour and sedimentation processes. The obtained results indicate that the sensor has the potential to provide a new monitoring device for scour and sediment deposition monitoring, and it is proposed to be further developed and assessed in laboratory and field conditions. This study aspires to contribute to the ongoing discourse on the use of sensing techniques to monitor, assess, and manage scour action effectively. Full article

Critical infrastructures such as transportation, power, telecommunication, water supply, and hospitals play a vital role in effectively managing post-disaster responses. The resilience of critical infrastructures should be incorporated in the planning and designing phase based on the risk assessment in a particular geographic area. However, the framework to assess critical infrastructure resilience (CIR) is variably conceptualised. Therefore, the objective of this study was to critically appraise the existing CIR assessment frameworks developed since the adoption of the Sendai Framework in 2015 with the hazard focus on earthquakes. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) method was used for the selection of the 24 most relevant studies, and these were analysed to delineate existing frameworks, models, and concepts. The study found that there are wide-ranging disparities among the existing frameworks to assess the infrastructure resilience, and it has become a key challenge to prioritise resilience-based investment in the infrastructure sector. Furthermore, key attributes such as performance indicators, emergency aspects, and damage assessment need to be considered for different disaster phases—ex-ante, during, and ex-post—to improve the long-term resilience of critical infrastructure. Subsequently, an integrated and adaptable infrastructure resilience assessment framework is proposed for proper critical infrastructure planning and resilience-based investment decision making. Full article

From the perspective of sustainable waste management and its environmental impact, waste biomass bottom ash (BA) remains problematic and challenging to use as a recycling material for civil engineering infrastructures. This study evaluated the performance of lateritic soil (LS), stabilized with cement and biomass BA, as a subbase material. BA has been considered a replacement material in LS prior to the introduction of hydraulic cement stabilization means. The geotechnical engineering tests comprised the modified Proctor test, the California Bearing Ratio (CBR) test, and the unconfined compression test. X-ray fluorescence (XRF) and X-ray diffraction (XRD) tests were conducted to investigate the mineralogical properties of the stabilized soil samples. The leachate test was performed with a permeability mold to measure the release of heavy metals. Finally, the benefits of using the stabilized subbase material were assessed using the mechanistic–empirical (M–E) pavement design approach. Based on the results obtained, the strength and stiffness characteristics of the stabilized soils indicate that the efficiency of the mix satisfied the Thailand highway specification. The admixture of 80% BA and 5% cement is suggested for use as a soil–cement subbase material for flexible pavements, due to its good engineering and environmental properties. The results of the M–E design demonstrate the effectiveness of the stabilized soil presented herein. The study’s outcomes are predicted to promote the utilization of waste BA as a promising pavement material. Full article

This study investigated the potential influence of operating water levels and loading conditions on the slope stability of an embankment dam. Four different operating reservoir levels (normal, reduced, embankment height, and overflow) were considered in the study. Numerical modeling was used to investigate the problem in the case of the Chardara dam within the Syrdarya catchment in Kazakhstan. Based on the drawdown rates and operating conditions, minimum factor of safety values ranging from 0.56 (total failure) to 2.5 were retrieved. Furthermore, a very high correlation was observed between drawdown days, the minimum factor of safety values, the maximum factor of safety values, and pore-water pressures, with correlation coefficients ranging from 0.561 to 0.997 (strong to very strong correlation). On the other hand, the highest negative correlation of 0.997 was observed between the minimum factor of safety values and pore-water pressures. Additionally, based on the results from the analysis of variance, three reservoir operating levels (normal, embankment height, and overflow) resulted in p-values less than 0.05, indicating that the variations in the factor of safety values from the drawdown rates were statistically significant. The findings of this study demonstrated that, not only may the drawdown rate be detrimental to the embankments, but that different operating levels can also affect slope stability in different ways. Full article

Optimizing the serviceability of highway bridges is a fundamental prerequisite to provide proper infrastructure safety and emergency responses after natural hazards such as an earthquake. In this regard, fragility and resilience assessment have emerged as important means of describing the potential seismic risk and recovery process under uncertain inputs. Generating such assessments requires estimating the seismic demand of bridge components consisting of piers, deck, abutment, bearing, etc. The conventional probabilistic model to estimate the seismic demands was introduced more than two decades ago. Despite an extensive body of research ever attempting to improve demand models, the univariate demand model is the most common method used in practice. This work presents a comprehensive review of the evolution of demand models capturing machine-learning-based methodologies and their advantage in comparison to the conventional model. This study sheds light on understanding the existing demand models and their associated attributes along with their limitations. This study also provides an appraisal of the application of probabilistic demand models to generate fragility curves and subsequent application in the resilience assessment of bridges. Moreover, as a sound reference, this study highlights opportunities for future development leading to enhancement of the performance and applicability of the demand models. Full article

The consensus in the Norwegian construction industry is that the projects are characterized by conflicts. Because unresolved disputes that reach courts take time and resources to be solved, this leads to lost productivity and high costs for all stakeholders. Of the root causes of conflicts identified previously, tender specification and contract understanding were the most significant issues. To expand on previous findings, a qualitative analysis of 58 formal, semi-structured interviews was conducted to determine whether personal characteristics and types of contracts presented conflicts. Interviews were conducted with contractors, public clients, consultants, academics, and lawyers. Data were analyzed using NVIVO 12.0 following specific relevant themes and thematic maps. Corrective and preventive actions included the development of a new method to produce better-prepared tender documents, knowledge building in contract management, training to ensure better communication and dialogue between client and contractor, trust-building, dispute resolution along the way, and avoid awarding contracts at the lowest price or the use of a hybrid model. Improved routines may drive costs down, and cooperation and new forms of tendering and contracting could be the key to prevent and minimize disputes in Norway. Full article

Despite advancing Internet of Things (IoT) technologies, road projects often rely on inaccurate supplier data, making it difficult to determine the cost, quantity, quality, and transportation duration of the needed materials. The wrong choice of material suppliers can lead the supply chain to suffer losses, directly affecting the project’s performance. In this regard, many studies have devised material logistics optimization models for road projects. However, the majority based their decisions on inaccurate or outdated data. This paper studies this gap by introducing a framework that utilizes IoT technologies and smart construction to feed optimization models with accurate and dynamically updated material data. This IoT-powered framework considers only quantitative criteria as input data to the integrated linear programming optimization model, precisely selected suppliers, and optimally calculated costs using MS Excel Solver. The results reveal that the framework is sensitive to any dynamic data updates and can achieve up to 40% material cost savings in real runtime. The paper demonstrates the proposed outline framework with a case study of planning an alternative road between Riyadh and Madinah cities in Saudi Arabia. Full article

Modern roadways provide road users with a comfortable and safe ride to their destinations. Due to increasing traffic demands and maximum allowable loads, road authorities should also pay attention to the structural soundness of road pavements while seeking cost-effective and timely maintenance or minor rehabilitation activities. This means that a sustainable pavement preservation strategy is needed that includes an optimal pavement condition assessment to support the appropriate decision-making processes. To address this need, this research study proposes an approach to integrate Non-Destructive Testing (NDT) data and ground truth data to predict the long-term performance of flexible pavements. Appropriate mechanistic models that take into account the nature of Asphalt Concrete (AC) materials are used for the analysis to increase the accuracy of the results when it comes to protecting and extending pavement life. The results indicated that examining viscoelastic behavior for AC appears to be a more conservative approach for the response analysis, as well as the fatigue performance analysis, compared to the most conventional assumptions for linear elastic materials. In accordance with common sense, AC temperature was considered as a critical factor for the related investigation. Overall, it may not be a good and reliable practice to continue the process of pavement management and maintenance decisions based on the approach of only one analysis type. Full article

Nano-technology has played a vital role in upgrading the durability and sustainability of asphalt pavements during the last decade. Conventional bitumen does not provide adequate performance against permanent deformation in severe weather conditions. Quartz nano-size particles (QNPs) (1, 3, and 5% by weight of the bitumen) were employed in this research to modify the conventional base bitumen PG 58–16. Conventional physical (penetration, softening, ductility, and flash and fire point), rheological, frequency sweep, high-performance grading, and moisture susceptibility tests were performed to investigate the enhancement of the base bitumen performance. Marshall mix design was conducted on each asphalt mixture to determine the optimum bitumen content (OBC) percentage for the preparation of wheel tracker samples to evaluate the effect of QNPs on asphalt mixtures. Laboratory test findings showed that the optimum concentration of QNPs is 5% by weight of base bitumen. The homogeneity and proper stable dispersion of QNPs in the bitumen were validated via scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and storage stability tests. At higher temperatures, the QNP-modified asphalt mixtures exhibited higher stiffness, stripping resistance, and rutting potential. It was concluded that QNPs effectively upgrade durability and permanent deformation resistance at high temperatures and, therefore, the sustainability of asphalt roads. Full article

Higher train speeds and heavier axle loads trigger elevated stresses and vibrations in the track, potentially increasing track deterioration rates and maintenance costs. Alternative track forms made of combinations of reinforced concrete and asphalt layers have been developed. A thorough understanding of the slab and asphalt tracks is needed to investigate track performance. Thus, analytical and numerical models have been developed and validated by many researchers. This paper reviews numerical models developed to investigate railway track performance. The synthesis of major finite element models is described in detail, highlighting the main components and their outputs. For slab track models, the use of a structural asphalt layer within the railway track remains an active research topic and firm conclusions on its efficacy are not yet available. It can be expected that slab track structures will also be affected by train-induced ground vibrations. There is thus a gap in the literature regarding the measurement of dynamic effects on high-speed railway lines, and further research is needed to investigate the dynamic behaviour of slab–asphalt track systems. In this review, novel solutions for mitigating the vibrations in high-speed rail are discussed and compared. The use of asphalt material in railways appears to have beneficial effects, such as increasing the bearing capacity and stiffness of the structure and improving its dynamic performance and responses, particularly under high-speed train loads. Full article

Steel plate shear walls (SPSW) structures have been widely employed in multistory residential buildings. The traditional welding process may lead to serious welding deformation due to the thinness of the plate. In this study, a new welding process is proposed to ensure that the stiffeners and SPSWs bend as a whole, and the number of welds is reduced from 3 to 2. This process has better integrity than the traditional process owing to less welding residual stress and deformation. On the basis of low-cycle reciprocating load tests on four full-scale specimens, the shear failure pattern, hysteresis characteristics, and load-carrying capacity of SPSWs affected by the new process are studied, and the new welding process used in the vertical stiffener can meet the requirements of shear capacity. The influences of various parameters on the shear resistance of the SPSWs made by the new welding process are compared and analyzed. The results indicate that the lateral stiffness of the frame and the width–height ratios of the wall significantly influence the load-carrying capacity of the SPSWs. The SPSWs adopting the new manufacturing process are numerically simulated using ANSYS software. The same conclusions can be obtained by comparing the numerical results with the experimental results. Full article

In order to achieve a comprehensive study regarding evacuation efficiency in underground space, globally accepted regulations and standards include, among other parameters, the maximum unimpeded travel speed of occupants in case of emergency evacuation. Researchers attempt to investigate the variation of travel speed using different approaches. The aim of this paper is to study occupants’ travel speed during evacuation procedures in an underground space. Underground spaces have special requirements as they differentiate from a typical building regarding the absence of physical lighting, the fact that exit route paths are always ascending and the limited orientation awareness of their users. A total of 40 volunteers participated in a large-scale experiment that involved the evacuation of the underground space in real time. Two distinct evacuation drills took place, the first one in a smoke-free environment and the second simulated fire conditions via the presence of dense artificial smoke. During each trial, the required evacuation time as well as the walking speed of each occupant were monitored, with the aid of digital cameras positioned in appropriate spots inside the underground space. The evacuation speed resulted from the experiments is compared to those of international regulations (e.g., NFPA 130) regarding horizontal travelling, as well as travelling on an upward staircase. The effect of the presence of smoke on evacuation speed is discussed. The importance of direct and constant guidance to the occupants of an underground space is highlighted during evacuation in a smoked environment and its contribution to safety improvement. Finally, the effect of the egress route type of an underground space on occupants’ speed is discussed and how this may affect the decision making during the design of an underground infrastructure, in order to achieve a safe environment. Full article

The harmonious development of urban rail transit, underground space engineering, and social economy is the key to regional sustainable development. Based on synergetic theory, this paper constructs the coupling coordination evaluation system of “rail transport-social economy” composite system at the scale of a city cluster. With this system, the coupling and coordinated development pattern and characteristics of “rail transit-social economy” in the Yangtze River Delta city cluster from 2002 to 2020 were analyzed. The paper makes a horizontal comparison with the Beijing-Tianjin-Hebei city cluster and the Pearl River Delta city cluster, as well as analyzes the differences in development and existing problems, and puts forward policy suggestions for rail and urban underground space development. The results show that: (1) The rail transit of 11 cities in the Yangtze River Delta shows a “step by step” development pattern. That is “national central city, provincial city, second-tier city, third-tier city, etc.”, accompanied by periodic changes of coupling and coordination degree. In addition, there is also the phenomenon of unbalanced development within the region; (2) From 2002 to 2020, the development of rail transit in the three city clusters shows a situation of “the overall supply is lacking and lags behind the social economy for a long time”. Among them, the Pearl River Delta city cluster has the most serious lags. Multi-channel financing, speeding up the construction of the rail transit scale according to local conditions, and improving operating efficiency are considered to be the keys to solve this problem; (3) In general, the coupling between rail transit and the social economy in the Yangtze River Delta city cluster is better than that in the Beijing-Tianjin-Hebei city cluster and the Pearl River Delta city cluster, but the coordination is at a slight disadvantage. Full article

The qualitative measurement is a common practice in infrastructure condition inspection when using Infrared Thermography (IRT), as it can effectively locate the defected area non-destructively and non-contact. However, a quantitative evaluation becomes more significant because it can help decision makers figure out specific compensation plans to deal with defects. In this work, an IRT-based novel damage index, damage density, was proposed to quantify the significance of subsurface defects. This index is extracted from IR images using our thermography analytics framework. The proposed framework includes thermal image processing, defect edge detection, and thermal gradient map calculations. A modified root mean square error (mRMSE), which is a novel modification to the existing RMSE, was compared to evaluate the performance of image processing methods. The results show that the histogram equalization performs better than the other methods in the image processing part as the mRMSE is the lowest among them. The Pearson correlation coefficient between the developed index and the volume of subsurface defects is 0.94, which indicates a positive linear relationship between them. Thus, the proposed damage index can be used to guide the engineering practices and maintenance decisions for the subsurface determination in the civil infrastructure. Full article

A huge volume of waste is generated by natural and human-made disasters and by rapid urbanization that leads to the demolition of structures reaching the end of their service life. Using recycled aggregates in concrete producing reduces environmental pollution by decreasing the disposal of this waste material in landfills and preserving unreasonable exploitation of natural resources. This manuscript presents the results of an experimental program aiming to study the effect of recycled aggregates on the physical and the mechanical properties of roller compacted concrete (RCC). A Dreux–Gorisse mix design method together with the modified proctor test were adopted to prepare a reference mixture with natural aggregates with three derived mixtures where coarse aggregates were replaced by 50%, 70%, and 100% of recycled aggregates. The physical properties of RCC were evaluated by means of water absorption and gas permeability tests while the mechanical properties were evaluated using compressive, tensile splitting and 3-point flexural tests. The results of physical tests showed that both water absorption ability and gas permeability increase proportionally with the replacement ratios. The results of the mechanical tests showed that the compressive strength class was approximately constant for all developed mixtures at the age of 28 days. For a substitution ratio of 100%, a drop in the compressive strength of only 6% was recorded. The reduction in the tensile and flexural strength was more pronounced than the compressive strength and was about 10% for the mixture of 100% recycled aggregates. It was found that the strength increases with time, and it can be estimated at any age using the analytical models adopted for conventional hydraulic concretes. Based on the obtained results, it was concluded that recycled aggregates up to 50% don’t negatively affect the physical and mechanical properties of RCC. Full article