Journal Description

Infrastructures — Open Access Journal

Infrastructures (ISSN 2412-3811) is an international scientific peer-reviewed open access journal on infrastructures published monthly online by MDPI. The journal collaborates with the Spanish Road Technology Platform /Plataforma Tecnológica Española de la Carretera (PTC). Infrastructures is affiliated to International Society for Maintenance and Rehabilitation of Transport Infrastructures (iSMARTi).

Open Access—free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: Indexed by Inspec (IET) and other databases, Scopus (2019 CiteScore: 1.3)
Rapid Publication: manuscripts are peer-reviewed and a first decision provided to authors approximately 11.6 days after submission; acceptance to publication is undertaken in 2.5 days (median values for papers published in this journal in the first half of 2020).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.

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Latest Articles

Open AccessArticle

A Strategic Move for Long-Term Bridge Performance within a Game Theory Framework by a Data-Driven Co-Active Mechanism

O. Brian Oyegbile and

Mi G. Chorzepa

Infrastructures 2020, 5(10), 79; https://doi.org/10.3390/infrastructures5100079 - 29 Sep 2020

Abstract

The Federal Highway Administration (FHWA) requires that states have less than 10% of the total deck area that is structurally deficient. It is a minimum risk benchmark for sustaining the National Highway System bridges. Yet, a decision-making framework is needed for obtaining the highest possible long-term return from investments on bridge maintenance, rehabilitation, and replacement (MRR). This study employs a data-driven coactive mechanism within a proposed game theory framework, which accounts for a strategic interaction between two players, the FHWA and a state Department of Transportation (DOT). The payoffs for the two players are quantified in terms of a change in service life. The proposed framework is used to investigate the element-level bridge inspection data from four US states (Georgia, Virginia, Pennsylvania, and New York). By reallocating 0.5% (from 10% to 10.5%) of the deck resources to expansion joints and joint seals, both federal and state transportation agencies (e.g., FHWA and state DOTs in the U.S.) will be able to improve the overall bridge performance. This strategic move in turn improves the deck condition by means of a co-active mechanism and yields a higher payoff for both players. It is concluded that the proposed game theory framework with a strategic move, which leverages element interactions for MRR, is most effective in New York where the average bridge service life is extended by 15 years. It is also concluded that the strategic move can lead to vastly different outcomes. Pennsylvania’s concrete bridge management strategy currently appears to leverage a co-active mechanism in its bridge MRR strategies. This is noteworthy because its bridges are exposed to similar environmental conditions to what is obtainable in Virginia and New York and are subjected to more aggressive weather conditions than those in Georgia. This study illustrates how a strategic move affects the payoffs of different players by numerically quantifying changes in service life from bridge time-dependent bridge performance relationships. Full article

(This article belongs to the Special Issue Innovate, Research, and Maintain Transportation Infrastructure)

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Open AccessArticle

Influence of Wall Thickness and Water Content on the Out-of-Plane Stability of Adobe Walls

Umaima Al Aqtash and

Paola Bandini

Infrastructures 2020, 5(9), 78; https://doi.org/10.3390/infrastructures5090078 - 22 Sep 2020

Abstract

This paper presents the results of a numerical study using the finite element method to assess the effect of wall thickness and a moist region along the wall base on the out-of-plane lateral stability of adobe walls. The models consisted of cantilever unreinforced adobe walls with a thickness of 25 cm, 30 cm, and 40 cm. Numerical analyses were performed for four lengths (L) of the moist region and for dry walls. The moist region was modelled with material characteristics corresponding to partially saturated and nearly saturated adobe. The results showed the detrimental effect of moisture along the lower portion of the wall on the out-of-plane lateral strength. The out-of-plane lateral strength reduction ratio dropped significantly as L increased. A high slenderness ratio was found to be critical for cantilever adobe walls when L extended beyond half of the wall length. The results provided insights concerning the role of wall thickness in the stability against overturning. Full article

(This article belongs to the Special Issue Selected Papers from the REHABEND 2020 Congress)

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Open AccessArticle

Maintenance Modelling of Ceramic Claddings in Pitched Roofs Based on the Evaluation of Their In Situ Degradation Condition

Cláudia Ferreira ,

Ana Silva ,

Jorge de Brito ,

Ilídio S. Dias and

Inês Flores-Colen

Infrastructures 2020, 5(9), 77; https://doi.org/10.3390/infrastructures5090077 - 22 Sep 2020

Abstract

Existing maintenance policies have several limitations, mainly due to the lack of knowledge regarding the durability and performance of buildings. Usually, the maintenance policies are insufficiently accurate, neglecting the risk of failure over time and the global costs associated with repairs. In this study, a condition-based maintenance model, based on Petri nets, is proposed to evaluate the impact of three maintenance strategies of ceramic claddings in pitched roofs (CCPR): MS1—only total replacement; MS2—composed of total replacement and minor intervention and MS3—composed of total replacement, minor intervention and cleaning operations. In this study, 146 CCPR were inspected in situ, with a total area of 43,991.6 m². The remaining service life of the CCPR; the global costs over the claddings’ lifetime (considering inspection, maintenance, replacement and disposal costs); the claddings’ degradation condition and the number of replacements during the time horizon are used to evaluate the performance of the different maintenance strategies through a simplified multi-criteria analysis. The results show that the gains in performance, in terms of expected service life and durability, of the consideration of preventive maintenance actions (minor interventions or cleaning operations) outweigh the increase of the operation costs. Full article

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Open AccessArticle

Inspection and Assessment of Corrosion in Pretensioned Concrete Bridge Girders Exposed to Coastal Climate

Magdalena J. Osmolska ,

Karla Hornbostel ,

Terje Kanstad ,

Max A.N. Hendriks and

Gro Markeset

Infrastructures 2020, 5(9), 76; https://doi.org/10.3390/infrastructures5090076 - 17 Sep 2020

Abstract

The most common methods for detecting chloride-induced corrosion in concrete bridges are half-cell potential (HCP) mapping, electrical resistivity (ER) measurements, and chloride concentration testing, combined with visual inspection and cover measurements. However, studies on corrosion detection in pretensioned structures are rare. To investigate the applicability and accuracy of the above methods for corrosion detection in pretensioned bridge girders, we measured pretensioned I-shaped girders exposed to the Norwegian coastal climate for 33 years. We found that, even combined, the above methods can only reliably identify general areas with various probabilities of corrosion. Despite severe concrete cracking and high chloride content, only small corrosion spots were found in strands. Because HCP cannot distinguish corrosion probability in the closely spaced strands from other electrically connected bars, the actual condition of individual strands can be found only when concrete cover is locally removed. Wet concrete with high chloride content and accordingly low HCP and low ER was found only in or near the girder support zones, which can therefore be considered the areas most susceptible to chloride-induced corrosion. We conclude by proposing a procedure for the inspection and assessment of pretensioned girders in a marine environment. Full article

(This article belongs to the Special Issue Structural Performances of Bridges)

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Open AccessArticle

Real-Time Road Hazard Information System

Carlos Pena-Caballero ,

Dongchul Kim ,

Adolfo Gonzalez ,

Osvaldo Castellanos ,

Angel Cantu and

Jungseok Ho

Infrastructures 2020, 5(9), 75; https://doi.org/10.3390/infrastructures5090075 - 09 Sep 2020

Abstract

Infrastructure is a significant factor in economic growth for systems of government. In order to increase economic productivity, maintaining infrastructure quality is essential. One of the elements of infrastructure is roads. Roads are means which help local and national economies be more productive. Furthermore, road damage such as potholes, debris, or cracks is the cause of many on-road accidents that have cost the lives of many drivers. In this paper, we propose a system that uses Convolutional Neural Networks to detect road degradations without data pre-processing. We utilize the state-of-the-art object detection algorithm, YOLO detector for the system. First, we developed a basic system working on data collecting, pre-processing, and classification. Secondly, we improved the classification performance achieving 97.98% in the overall model testing, and then we utilized pixel-level classification and detection with a method called semantic segmentation. We were able to achieve decent results using this method to detect and classify four different classes (Manhole, Pothole, Blurred Crosswalk, Blurred Street Line). We trained a segmentation model that recognizes the four classes mentioned above and achieved great results with this model allowing the machine to effectively and correctly identify and classify our four classes in an image. Although we obtained excellent accuracy from the detectors, these do not perform particularly well on embedded systems due to their network size. Therefore, we opted for a smaller, less accurate detector that will run in real time on a cheap embedded system, like the Google Coral Dev Board, without needing a powerful and expensive GPU. Full article

(This article belongs to the Section Infrastructures Inspection and Maintenance)

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Open AccessArticle

A Dissipating Frames for Seismic Retrofitting and Building Energy-Efficiency

Dora Foti ,

Francesco Ruggiero ,

Maria Francesca Sabbà and

Michela Lerna

Infrastructures 2020, 5(9), 74; https://doi.org/10.3390/infrastructures5090074 - 08 Sep 2020

Abstract

In the present paper a new and innovative way to approach the regeneration of public buildings and public housing is proposed. It consists in a dissipative steel frame to reduce the displacement demand and to improve the energy efficiency of a real existing structure, inserting buckling-restrained axial dampers (BRAD) type dissipative braces. This system is adaptable to any construction made of reinforced concrete frames and improves energy efficiency and earthquake-resistant performance; moreover, it upgrades the aesthetics of buildings and the quality of life for the users. In fact, the system is capable of assuming different and pleasant architectural shapes offering benefits in terms of earthquake-resistant performance, energy saving, and energy production from renewable sources. The attention to the aesthetic results renders the intervention a redevelopment strategy not only on an architectural scale, but also in the urban contexts for degraded and marginalized suburbs. The performances of the proposed kit were evaluated on a case study consisting in a social house located in the south of Italy. Numerical analyses have been carried out and the results have been reported both from the seismic protection and energy efficiency points of view. As a result, the produced renewable energy from the retrofitting system and the building seismic capacity increased. A rapid and precise control process, able to return a suitable structural dimensioning of the frame, according to the different application contexts, is finally proposed. Full article

(This article belongs to the Special Issue Seismic Performance Improvement and Energy Optimization for Structures)

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Open AccessArticle

Cost Overruns in Tunnelling Projects: Investigating the Impact of Geological and Geotechnical Uncertainty Using Case Studies

Chrysothemis Paraskevopoulou and

Georgios Boutsis

Infrastructures 2020, 5(9), 73; https://doi.org/10.3390/infrastructures5090073 - 08 Sep 2020

Abstract

Tunnelling projects seldom meet the initial budget requirements. Commonly, these types of projects suffer from cost overruns, which subsequently lead to project delivery delays mainly due to unsuccessful ground investigation as specified in the literature. The presented work scrutinises the effect of ground investigation in cost overruns. More specifically, various cost figures (total cost, construction cost, tunnel cost) are analysed for two case studies i) the Channel tunnel in the UK and ii) the Olmos Tunnel in Peru. Clayton’s relation between ground investigation and the construction cost is utilised and further investigated. In the Channel tunnel, the main problems faced led to a cost overrun of 78% for the total cost, 66% for the construction cost and 77% for the tunnelling cost. In the Olmos tunnel, two main geological scenarios are analysed and the construction cost overrun is calculated at 9.6% and 6.7%. Drawing on the conclusions, this research work proves that ground investigation can be one of the major factors influencing the tunnel cost. Full article

(This article belongs to the Special Issue Underground Infrastructure Engineering)

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Open AccessArticle

Seismic Capacity Estimation of a Masonry Bell-Tower with Verticality Imperfection Detected by a Drone-Assisted Survey

Francesco Micelli ,

Alessio Cascardi and

Maria Antonietta Aiello

Infrastructures 2020, 5(9), 72; https://doi.org/10.3390/infrastructures5090072 - 08 Sep 2020

Abstract

Masonry towers are considered an important part of cultural heritage due to their architectural and historical value. From a structural perspective these kind of buildings are considered slender elements, the same as a cantilever beam. In real cases it is not easy to model with high accuracy these heritage constructions, since the geometry and mechanical properties of the constituent materials are not adequately known. On the other hand, a deep knowledge of the structural and seismic vulnerability of the masonry towers is needed in order to preserve and retrofit, when necessary, their architectural and cultural value. In the present research an exhaustive study is presented, as it regards the assessment of the seismic vulnerability of a heritage masonry bell-tower, built in the 14th century. An innovative protocol of structural survey followed, and it is proposed herein. The geometry of the tower was easily obtained by digital photogrammetry assisted by a drone. The geometrical model was easily converted into a digitalized input, that was introduced into a finite element method (FEM)-based code. The 3D model was used for linear static, linear dynamic and nonlinear static (pushover) structural analyses. The vulnerability of the masonry tower was assessed and at least one kinematic was found to be not verified. Full article

(This article belongs to the Special Issue Selected Papers from the REHABEND 2020 Congress)

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Open AccessArticle

Failures of the Cast-Iron Columns of Historic Buildings—Case Studies

Michał Gołdyn and

Tadeusz Urban

Infrastructures 2020, 5(9), 71; https://doi.org/10.3390/infrastructures5090071 - 02 Sep 2020

Abstract

Selected technical problems related to the rehabilitation of cast-iron columns in structures from the turn of the 19th and 20th century are discussed in the paper. Lack of contemporary standard regulations related to the design of cast-iron structures is a significant problem in the design works and experimental investigations on cast-iron columns are frequently required. The paper presents results of the tests concerning principal properties of cast-iron—strength and deformability. The historical design principles are discussed in the light of the results of experimental investigations. As it was demonstrated, the actual load-carrying capacities of cast-iron columns may exceed by several times the values resulting from the 20th century design rules. The conservatism of the design principles resulted, however, from the material uncertainties—lack of homogeneity and hidden defects of the cast-iron. Selected examples of failures of cast-iron columns from 19th-century structures such as post-industrial buildings and engineering structures are discussed. They resulted from errors made during adaptation works. The reasons for these failures and considered methods of repairing the structures are presented. Full article

(This article belongs to the Special Issue Selected Papers from the REHABEND 2020 Congress)

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Open AccessArticle

Microstructure Analysis and Strength Characterization of Recycled Base and Sub-Base Materials Using Scanning Electron Microscope

Tanvir Imtiaz ,

Asif Ahmed ,

MD Sahadat Hossain and

Mohammad Faysal

Infrastructures 2020, 5(9), 70; https://doi.org/10.3390/infrastructures5090070 - 28 Aug 2020

Abstract

The reuse of recycled crushed concrete aggregate (RCCA) and reclaimed asphalt pavement (RAP) can provide a sustainable solution for the disposal of C&D waste materials instead of sending them to landfills. More importantly, it will conserve energy and reduce environmental concerns. Several states in the USA have been using RCCA and RAP as base materials for years, focusing on the quality of the recycled materials. The structure of Recycled Aggregate (RA) is more complex than that of Natural Aggregate (NA). RAs have old mortar adhered on them that forms a porous surface at the interfacial transition Zone (ITZ) and prevents new cement mix from bonding strongly with the aggregates. The objective of this study was to correlate microstructural properties such as microporosity, inter and intra aggregate pores with the unconfined compressive strength (UCS) of RAP and RCCA molds, mixed at different proportions. In this paper, the quantity of micropores and their effect on the strength of mixed materials is used as the basis of microstructural analysis of recycled concrete and reclaimed asphalt. Microstructural properties obtained from analyzing scanning electron microscope (SEM) images were correlated with unconfined compressive strength. Intra-aggregate and interaggregate pores were studied for different ratios of cement treated mixture of RAP and RCCA. The results show that addition of RAP considerably increases the number of pores in the mixture, which eventually causes reduction in unconfined compressive strength. In addition, significant morphological and textural changes of recycled aggregates were observed by SEM image analysis. Full article

(This article belongs to the Special Issue Geomaterials for Transportation Infrastructures)

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Open AccessArticle

The Selected Issues of Adaptation of 19th and 20th Century Post-Industrial Buildings in Łódź

Tadeusz Urban and

Michał Gołdyn

Infrastructures 2020, 5(8), 69; https://doi.org/10.3390/infrastructures5080069 - 18 Aug 2020

Abstract

The paper deals with selected technical problems related to the adaptation for new uses of the structure of existing post-industrial buildings from the turn of the 19th and 20th centuries. A major difficulty is the fact that the strength and geometric properties of cast-iron, steel, and masonry elements often differ significantly from the values characterizing contemporary materials. Due to uncertainty regarding the load-carrying capacity of historical structures, in many cases there is a need to carry out destructive tests of elements taken from the buildings. As the example of cast-iron girders in the former spinning mill of “I. Poznański” demonstrated, such tests can prove a significant margin of load-carrying capacity and confirm the possibility of adapting the structure to new purposes. The paper also presents examples of strengthening the existing wooden ceilings by joining with the reinforced concrete structure, which allowed the keeping of the original elements and an increase of the allowable load. Selected problems related to the assessment of historical masonry structures were also described. The discussed examples of structural failures showed that they often resulted from incorrect assessment of the strength of historical masonry elements as well as improperly conducted construction works. Full article

(This article belongs to the Special Issue Selected Papers from the REHABEND 2020 Congress)

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Open AccessArticle

Development of a Method to Study Evaporation of a Volatile Solvent in an Isolated Subsurface Structure: A Practical Exercise in Risk Minimization

Thomas Neil McManus ,

Ana Rosa and

Assed Haddad

Infrastructures 2020, 5(8), 68; https://doi.org/10.3390/infrastructures5080068 - 08 Aug 2020

Abstract

This article describes development and confirmatory testing of a method to study the evaporation of a volatile solvent containing ignitable ingredients in an isolated subsurface structure, a type of confined space. Accidental spillage and surreptitious disposal of chemical products in streets create a risk of fire and explosions in these structures. Development of the method included consideration about instrument safety; personal exposure; volume of the structure (2.5 m³); evaporation rate; temperature of the airspace; and number of opening(s) in the manhole cover. Confirmatory testing utilized 10 mL of lacquer thinner (60% to 80% toluene, 10% to 20% methylethyl ketone (MEK), 5% to 10% methanol and 1% to 9% acetone) on a wetted paper towel positioned near the bottom of the structure. This methodology produced a maximum of 2150 ppm of ‘isobutylene units’ on a PID (PhotoIonization sensor) positioned about 15 cm above the sample. This concentration corresponds to about 1140 ppm of toluene (less than 10% of the Lower Flammable Limit of 12,700 ppm). This method offers a stable, safe platform for study of the process. Evaporation of solvent and exchange between the external atmosphere and the airspace regulate the concentration of vapor, which can typically persist for 24 to 48 h. Full article

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Open AccessArticle

Reliability Analysis of Intersection Sight Distance at Roundabouts

Said M. Easa ,

Yang Ma ,

Shixu Liu ,

Yanqun Yang and

Shriniwas Arkatkar

Infrastructures 2020, 5(8), 67; https://doi.org/10.3390/infrastructures5080067 - 06 Aug 2020

Abstract

This paper presents a reliability-based method for the design of intersection sight distance (ISD) at traffic roundabouts using the linear and nonlinear deceleration profiles of the entry vehicles. The reliability method is based on the first-order second moment method which is simple and relatively accurate compared with advanced methods. The nonlinear deceleration profile includes a shape parameter that produces the linear profile as a special case. Deterministic and reliability-based formulas for the required ISD for an approaching vehicle are developed for the entry vehicle on the left and the vehicle on the circulating roadway. Then, the design values of the ISD legs, applicable to any type of roundabout, are presented for different probabilities of non-compliance (P_nc) and different coefficients of variations. For the special case of single-lane symmetrical roundabouts, which have a well-defined geometry, the lateral clearance needs are established. The sensitivity analysis shows that ISD is very sensitive to both the mean and variance of the critical headway. The results show that the deterministic method results in ISD values that correspond to a very small P_nc, indicating that the method is very conservative. The proposed method, which provides flexibility in selecting ISD for any given P_nc, should be of interest to highway designers and practitioners to promote roundabout safety. Full article

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Open AccessReview

Review of Enzyme-Induced Calcite Precipitation as a Ground-Improvement Technique

Heriansyah Putra ,

Hideaki Yasuhara ,

Erizal ,

Sutoyo and

Muhammad Fauzan

Infrastructures 2020, 5(8), 66; https://doi.org/10.3390/infrastructures5080066 - 05 Aug 2020

Abstract

Calcite-induced precipitation methods (CIPMs) have recently become potential techniques in geotechnical engineering for improving the shear strength of sandy soil. One of the most promising methods among them is enzyme-induced calcite precipitation (EICP). In this technique, a mixed solution composed of reagents and the urease enzyme, which produces calcite, is utilized as the grouting material. The precipitated calcite in granular soil provides ties among the grains of soil and limits their mobility, thus promoting an improvement in strength and stiffness and also a reduction in the hydraulic conductivity of sandy soil. This paper discusses the potential increase in the strength and stiffness of the soil, the additional materials for grouting, the effect of these materials on the treatment process, and the engineering properties of the soil. The possible sources of the urease enzyme and the applicability of the EICP method to other soil types are also discussed in this paper. The environmental and economic impacts of the application of EICP are also presented. The envisioned plans for application, potential advantages, and limitations of EICP for soil stabilization are discussed. Finally, the primary challenges and opportunities for development in future research are briefly addressed. Full article

(This article belongs to the Special Issue Geomaterials for Transportation Infrastructures)

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Open AccessArticle

Accuracy Comparison of Aerial Lidar, Mobile-Terrestrial Lidar, and UAV Photogrammetric Capture Data Elevations over Different Terrain Types

Ryen Johnson and

Infrastructures 2020, 5(8), 65; https://doi.org/10.3390/infrastructures5080065 - 31 Jul 2020

Abstract

Lidar and other remotely sensed data such as UAV photogrammetric data capture are being collected and utilized for roadway design on an increasing basis. These methods are desirable over conventional survey due to their efficiency and cost-effectiveness over large areas. A high degree of relative accuracy is achievable through the establishment of survey control. In this case study, elevations (z-values) derived from mobile-terrestrial lidar, aerial lidar, and UAV photogrammetric capture collected with survey control were statistically compared to conventionally surveyed elevations. A cost comparison of the methods is also included. Each set of z-values corresponds to a discrete horizontal point originally part of the conventional survey, collected as cross-sections. These cross-sections were surveyed at three approximate tenth-mile sample locations along US-30 near Georgetown, Idaho. The cross-sections were collected as elevational accuracy verification, and each sample location was selected as an area where the mobile-terrestrial lidar in particular was expected to have more difficulty achieving accuracy off the road surface. Processing and analysis were performed in Esri ArcMap 10.6, and all data were obtained from the Idaho Transportation Department, District 5. Overall, the aerial lidar elevations were found to be closest to conventionally surveyed elevations; on road surface and level terrain, mobile-terrestrial and UAV photogrammetric capture elevations were closer to the conventionally measured elevations. Full article

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Open AccessArticle

Ground Loss and Static Soil–Structure Interaction during Urban Tunnel Excavation: Evidence from the Excavation of the Athens Metro

Villy Kontogianni and

Stathis C. Stiros

Infrastructures 2020, 5(8), 64; https://doi.org/10.3390/infrastructures5080064 - 31 Jul 2020

Abstract

Ground settlement above urban tunnels is a threat for nearby buildings, because it may lead to their differential settlement, tilting, and damage, depending on their structural characteristics, on ground conditions, and on the excavation procedure. Still, for few cases only details on ground settlement are known. In this article we analyze ground subsidence data during the excavation of Lines 2 and 3 of the Athens Metro. Based on this evidence, and in comparison with previous studies, we show that observations of elevation changes and of tilting of buildings may underestimate the amount of ground loss; this is because part of the ground deformation may be compensated by the stiffness of buildings or accommodated by internal deformation of sizeable buildings hosting measuring benchmarks. This effect can be described as static soil–structure interaction (sSSI), in analogy to the dynamic SSI produced during earthquakes. sSSI can produce bias in monitoring data above an advancing tunnel front, leading to skew and not to symmetric subsidence curves if observations are made on one side on buildings and on the other side in open spaces (‘greenfields’). Furthermore, we show that ‘bowls’ of increased subsidence are observed along subsidence troughs during excavation; such ‘bowls’, not infrequently underestimated because of sSSI, may conceal a potential for sinkholes and other types of failure. Isolated towers on the contrary describe well ground subsidence and tilting. Full article

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Open AccessArticle

A Piecewise-Defined Function for Modelling Traffic Noise on Urban Roads

Mariano Gallo

Infrastructures 2020, 5(8), 63; https://doi.org/10.3390/infrastructures5080063 - 29 Jul 2020

Abstract

In this paper, a piecewise-defined function is proposed to estimate traffic noise in urban areas. The proposed approach allows the use of the model even in the case of very low or zero flows for which the classical logarithmic form is not suitable. A model based on the proposed approach is calibrated for a real case and compared with the results obtained with a model based only on the logarithmic form. The results obtained show how the proposed piecewise-defined function, linear for low traffic flows and logarithmic for medium-high volumes, is able to better represent real noise pollution levels in all conditions. The proposed approach is particularly useful when comparing two plan scenarios from the point of view of noise effects. Full article

(This article belongs to the Special Issue Transport Systems: Safety Modeling, Visions and Strategies)

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Open AccessArticle

Understanding Multi-Vehicle Collision Patterns on Freeways—A Machine Learning Approach

Clint Morris and

Jidong J. Yang

Infrastructures 2020, 5(8), 62; https://doi.org/10.3390/infrastructures5080062 - 24 Jul 2020

Abstract

Generating meaningful inferences from crash data is vital to improving highway safety. Classic statistical methods are fundamental to crash data analysis and often regarded for their interpretability. However, given the complexity of crash mechanisms and associated heterogeneity, classic statistical methods, which lack versatility, might not be sufficient for granular crash analysis because of the high dimensional features involved in crash-related data. In contrast, machine learning approaches, which are more flexible in structure and capable of harnessing richer data sources available today, emerges as a suitable alternative. With the aid of new methods for model interpretation, the complex machine learning models, previously considered enigmatic, can be properly interpreted. In this study, two modern machine learning techniques, Linear Discriminate Analysis and eXtreme Gradient Boosting, were explored to classify three major types of multi-vehicle crashes (i.e., rear-end, same-direction sideswipe, and angle) occurred on Interstate 285 in Georgia. The study demonstrated the utility and versatility of modern machine learning methods in the context of crash analysis, particularly in understanding the potential features underlying different crash patterns on freeways. Full article

(This article belongs to the Special Issue Innovate, Research, and Maintain Transportation Infrastructure)

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Open AccessArticle

Handling Imbalanced Data in Road Crash Severity Prediction by Machine Learning Algorithms

Nicholas Fiorentini and

Massimo Losa

Infrastructures 2020, 5(7), 61; https://doi.org/10.3390/infrastructures5070061 - 20 Jul 2020

Cited by 1

Abstract

Crash severity is undoubtedly a fundamental aspect of a crash event. Although machine learning algorithms for predicting crash severity have recently gained interest by the academic community, there is a significant trend towards neglecting the fact that crash datasets are acutely imbalanced. Overlooking this fact generally leads to weak classifiers for predicting the minority class (crashes with higher severity). In this paper, in order to handle imbalanced accident datasets and provide a better prediction for the minority class, the random undersampling the majority class (RUMC) technique is used. By employing an imbalanced and a RUMC-based balanced training set, we propose the calibration, validation, and evaluation of four different crash severity predictive models, including random tree, k-nearest neighbor, logistic regression, and random forest. Accuracy, true positive rate (recall), false positive rate, true negative rate, precision, F₁-score, and the confusion matrix have been calculated to assess the performance. Outcomes show that RUMC-based models provide an enhancement in the reliability of the classifiers for detecting fatal crashes and those causing injury. Indeed, in imbalanced models, the true positive rate for predicting fatal crashes and those causing injury spans from 0% (logistic regression) to 18.3% (k-nearest neighbor), while for the RUMC-based models, it spans from 52.5% (RUMC-based logistic regression) to 57.2% (RUMC-based k-nearest neighbor). Organizations and decision-makers could make use of RUMC and machine learning algorithms in predicting the severity of a crash occurrence, managing the present, and planning the future of their works. Full article

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Open AccessArticle

Aeroelastic Response of Suspended Pedestrian Bridges Made of Laminated Wood and Hemp

Fabio Rizzo

Infrastructures 2020, 5(7), 60; https://doi.org/10.3390/infrastructures5070060 - 20 Jul 2020

Abstract

The work described in this paper investigated, by calculating critical flutter speed, the aeroelastic response of suspended pedestrian bridges made of a laminated wood structure and hemp cables and compared them to bridges with a steel structure and harmonic steel cables. Critical flutter speed was estimated using a numerical two degree of freedom (2-DOF) generalized deck model based on finite-element modal analysis. The critical flutter speeds of two sets of 25 different structural configurations, obtained by varying the deck chord and the permanent deck loads, made of steel and of laminated wood respectively, were estimated using experimental flutter derivatives obtained from 30 wind tunnel experiments. One of the most significant results was that pedestrian bridges made of laminated wood and hemp have a higher torsional frequency than those made of steel and that this affects critical flutter speed. A case study was performed and discussed by analyzing the structural and aeroelastic response of a 250 m pedestrian bridge with a 12 m deck chord and two approximately 32 m tall towers. Full article

(This article belongs to the Special Issue Innovative Materials and Sustainable Infrastructure Construction)

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Special Issue in Infrastructures

Selected Papers from the REHABEND 2020 Congress Guest Editors: Ignacio Lombillo, Haydee Blanco, Yosbel Boffill, Luis Villegas
Deadline: 30 September 2020

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Geomaterials for Transportation Infrastructures Guest Editors: Md Rashadul Islam, Sadik Khan, Asif Ahmed
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Technologies and Methodologies for the Assessment of Structures and Infrastructures in the Presence of Natural Hazards Guest Editors: Carlo Rainieri, Giovanni Fabbrocino
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Sustainability of Concrete Infrastructures: New Applications, Monitoring and Retrofitting Guest Editors: Carmine Lima, Flavio Stochino
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