Infrastructures, Volume 6, Issue 5 (May 2021) – 16 articles

In a global society, in which geotechnical projects are increasingly designed in a country other than the one where construction takes place, geotechnical risk management must be extended to cover infrastructure works, which are smaller than dams and tunnels, for example, since there is a significant impact on works budget imponderables. Therefore, a risk management methodology based on the likelihood of the occurrence of certain events and their economic consequences is proposed, which is applicable to bored piles (Kelly drilled) in coarse soils, easy to use, and simple to implement since the initial stage of construction. Of 12 case studies of construction works involving bored piles (Kelly drilled) carried out in Luanda (Angola), two selected examples involving the proposed risk methodology on sandy soil layers with interbedded clays are discussed. Subsequently, whether the overall foundation contract budget is affected by assessed risk is determined, and what influence it has on the budget in the light of mitigating factors and associated real costs. This method intended to encourage the adaptation of sustainable risk management in bored piles construction by the site project managers, involving risk analysis concurrently with budgetary review. Though the level of assessed technical risk may be acceptable, overall costs associated with the contract in question may not be acceptable. Full article

Climate change is modifying scientific attitudes toward pre- and post-event assessments of natural hazards. Unprecedented levels of destruction need renewed focus on addressing and protecting communities forcing the decision makers to change their attention to vulnerability and risk assessment. In particular, society and economy rely heavily on infrastructures, as fundamental links for movement of goods and people, and are extremely vulnerable to multiple hazards (such as droughts, floods, storms, and coastal hazards). In this regard, resilience quantifies the recovery time and procedures to facilitate and enhance pre-hazard and post-hazard event mitigation and emergency response strategies of systems and entire communities. Resilience calculation depends on two important contributions: loss and recovery models that need to consider the effects of climate change. This paper aims to propose a methodology that implements the most recent approaches to assess climate change inside the traditional framework of resilience. The proposed framework is then applied to a case study of a bridge. Full article

In case of massive fire incidents in tunnels, ceiling lights are covered by dense smoke, and pedestrians must evacuate in the dark tunnel with almost zero visibility. Nonetheless, the walking behavior in a completely darkened tunnel has not been clarified. In this study, we experimentally attempted to investigate the evacuation loci and assess the stress of evacuees by measuring oxytocin and cortisol concentrations in saliva, heart rates, blood pressures, and responses in a survey questionnaire for a full-scale tunnel. Results indicated few differences in both one- and two-dimensional walking speed. In terms of stress, the group of subjects who felt stress demonstrated a walking speed that is 0.17 m/s slower than the group that did not feel it. In the questionnaire survey, most of the subjects answered that the wall was the most helpful item, followed by the unevenness (bumps) on the white lines on the road. One of the subjects became lost, stating that she could not find the unevenness (bumps) on the white lines. These two factors can be rational guides in a dense smoke environment or a completely dark tunnel scenario. Full article

This study was conducted on concrete using sewage sludge ash (SSA) with the aim to establish an efficient use of SSA as a cement replacement material. Concrete specimens with three degrees of strength were made from two different SSAs and exposed in temperate plain and cold mountain regions for a prolonged period of time to investigate the long-term properties of SSA concrete. After 17 years of exposure, the properties of the specimens were examined. SSA concrete basically maintained its strength after 17 years of exposure. No significant drop in the relative dynamic modulus of elasticity was detected in SSA concrete left in a cold mountain region, despite the fact that it would be exposed to a considerable number of freeze-and-thaw cycles. It was also confirmed that the SSA concrete exhibited high resistance against carbonation. A small amount of Katoite formed in the hardened cement/SSA mixture, probably due to the high content of Al₂O₃ in SSA. No abnormal formation of ettringite was observed. Full article

Although the design of jointed plain concrete pavements could be solved by commercial software, there is still a need for simple tools to be used in feasibility studies and preliminary cost–benefit analyses. This paper analyzed and verified jointed plain concrete pavements for airports composed of square slabs without tie and dowel bars. The examined slabs are laid on a cement-treated base layer and a stabilized granular subbase layer. The finite element software FAARFIELD was used to design the JPCP pavements when they are subjected to the design of the airplane (i.e., turboprop C-130J Hercules) under different conditions. Seven subgrade load bearing capacity values, twenty traffic levels, and two construction hypotheses (i.e., constant or variable thickness of the two deeper layers) were designed and then verified with the Westergaard theory in order to present a proposal for a catalogue. Finally, the construction cost per unit surface area was calculated for different construction methods of paving (by slip form paver or by fixed form). The obtained results provide a simple and fast procedure to design preliminary airport JPCPs. Full article

About 36% of fatal road accidents in Norway involve at least one driver who is “at work”. It has been argued that the implementation of rules clearly defining the responsibility of road transport companies to prevent work related accidents, by implementing safety management systems (SMS), could lead to increased safety. In the present study we tested the validity of this suggestion, by examining the influence of different sector rules on work-related accident prevention in Norwegian road and maritime transport. In contrast to the road sector, the maritime sector has had rules requiring SMS for over 20 years, clearly defining the shipping companies responsibility for prevention of work-related accidents. The aims of the study were to: (1) examine how the different sector rules influence perceptions of whether the responsibility to prevent work-related accidents is clearly defined in each sector; and (2) compare respondents’ perceptions of the quality of their sectors’ efforts to prevent work-related accidents, and factors influencing this. The study was based on a small-scale survey (N = 112) and qualitative interviews with sector experts (N = 17) from companies, authorities, and NGOs in the road and the maritime sectors. Results indicate that respondents in the maritime sector perceive the responsibility to prevent work-related accidents as far more clearly defined, and they rate their sector’s efforts to prevent accidents as higher than respondents in road. Multivariate analyses indicate that this is related to the scope of safety regulations in the sectors studied, controlled for several important framework conditions. Based on the results, we conclude that the implementation of SMS rules focused on transport companies’ responsibility to prevent work-related accidents could improve safety in the road sector. However, due to barriers to SMS implementation in the road sector, we suggest starting with a simplified version of SMS. Full article

The protection of infrastructure that is critical to society’s functionality, survival and progression has gained significance because of its large-scale and interdependent nature. This complex system-of-system (SoS) imposes extensive requirements on governance efforts to foster critical infrastructure protection (CIP). This paper uses the kaleidoscope for integrative system analysis (KISA) to investigate a Swedish approach for CIP against power shortages, called Styrel. Based on multiple sources of evidence, such as documents with regard to the case, interviews and a survey with involved experts, the analysis focuses on the system of emergency planning and the usage of the resulting plan. The results deliver insights into the governance of the multi-level planning, including issues regarding policies, the management and operation of Styrel, and accelerating problems in the adaption, emergence and entropy of the SoS, during and between process iterations. Since this large-scale approach largely fails to involve the private sector to enhance the resilience of the society, this proceeding results in uncalculated consequences. In addition, the current design of the approach hampers transparency and evaluation, which poses obstacles to the cultivation of mutual trust, collective learning and a shared understanding as well as proper risk communication with the wider public. Full article

Saltmarshes, known to be ecologically sensitive areas, face disturbances such as vegetation dieback due to anthropogenic activities such as construction. The current construction specifications recommended by state highway agencies do not specifically require documenting or restoring any prior saltmarsh soil/interstitial water properties, nor do they require re-establishing saltmarsh vegetation; restoring the abiotic properties and appropriate vegetation would enhance the long-term functionality and ecology of a disturbed area. In order to have a successful restoration of disturbed saltmarshes with healthy vegetation, the relationship between vegetative species and the properties of saltmarsh soils and interstitial water must be fully understood. In this study, field and laboratory tests were conducted for the soil samples from eight different saltmarsh sites in the Southeastern US Atlantic coastal region, followed by the development of a random forest model; the aim is to identify correlation among saltmarsh predominant vegetation types, redox potential, and salinity. The results reveal that moisture content and sand content are two main drivers for the bulk density of saltmarsh soils, which directly affect plant growth and likely root development. Moreover, it is concluded that deploying modern machine learning algorithms, such as random forest, can help to identify desirable saltmarsh soil/water properties for re-establishing vegetative cover with the reduced time after construction activities. Full article

This study addresses the feasibility of reusing pre-damaged steel beams in temporary structures. The extensive structural investigation of notch-damaged, unrepaired, and laterally unsupported steel beams was performed experimentally and numerically. The simply supported specimens were tested in two-point loading with the study parameters being the location and size of the notch. Some beams had one notch on one edge of the tension flange at different locations, and some beams had two notches on both edges of the tension flange. Three-dimensional numerical models were generated to simulate the behavior of the test beams. After verifying the model, the numerical analysis was extended to cover additional different notch depths and widths. The study showed that the capacity of beams with single notch was more influenced by the notch depth increase than it was by the increase in the notch width. Beams with double notches exhibited an even more pronounced and distinct decrease in the capacity as the notch depth and width increased. This investigation supports the feasibility of reusing pre-damaged steel beams in temporary structures under service loads and certain levels of damage, where the behavior of such beams is within the elastic range and the beam maximum defection is less than the allowable one. Full article

High speed rail (HSR) networks have been an essential catalyst in stimulating and balancing regional economic growth that ultimately benefits the society as a whole. Previous studies have revealed that HSR services sustainably yield superior social values for people, especially for adults and those of working age. This has become an advantage of HSR networks over other forms of public transportation. The Shinkansen network in Japan is one of most successful HSR models. Its services bring significant social advantages to the communities it serves, such as shorter travel times and increased job opportunities. Nevertheless, the societal impact of HSR networks depends on many factors, and the benefits of HSR could also be overrated. The goal of this research is to measure the socioeconomic impacts of HSR on people of all genders and age groups. The outcomes could lead to more suitable development of HSR projects and policies. This study investigates data sets for Japanese social factors over 55 years in order to determine the impacts of HSR. The assessment model has been established using Python. It applies Pearson’s correlation (PCC) technique as its main methodology. This study broadly assesses social impacts on population dynamics, education, age dependency, job opportunities, and mortality rate using an unparalleled dataset spanning 55 years of social factors. The results exhibit that younger generations have the most benefits in terms of equal educational accessibility. However, the growth of the HSR network does not influence an increase in the employment rate or labour force numbers, resulting in little benefit to the workforce. Full article

Time-based smart home controllers govern their environment with a predefined routine, without knowing if this is the most efficient way. Finding a suitable model to predict energy consumption could prove to be an optimal method to manage the electricity usage. The work presented in this paper outlines the development of a prediction model that controls electricity consumption in a home, adapting to external environmental conditions and occupation. A backup geyser element in a solar geyser solution is identified as a metric for more efficient control than a time-based controller. The system is able to record multiple remote sensor readings from Internet of Things devices, built and based on an ESP8266 microcontroller, to a central SQL database that includes the hot water usage and heating patterns. Official weather predictions replace physical sensors, to provide the data for the environmental conditions. Fuzzification categorises the warm water usage from the multiple sensor recordings into four linguistic terms (None, Low, Medium and High). Partitioning clustering determines the relationship patterns between weather predictions and solar heating efficiency. Next, a hidden Markov model predicts solar heating efficiency, with the Viterbi algorithm calculating the geyser heating predictions, and the Baum–Welch algorithm for training the system. Warm water usage and solar heating efficiency predictions are used to calculate the optimal time periods to heat the water through electrical energy. Simulations with historical data are used for the evaluation and validation of the approach, by comparing the algorithm efficiency against time-based heating. In a simulation, the intelligent controller is 19.9% more efficient than a time-based controller, with higher warm water temperatures during the day. Furthermore, it is demonstrated that a controller, with knowledge of external conditions, can be switched on 728 times less than a time-based controller. Full article

This paper presents the behavior of concrete-filled steel tube (CFST) columns infilled with fiber-reinforced self-consolidating ultrahigh strength concrete (UHSC) subjected to axial concentric monotonic loading to failure. UHSC is expected to improve ease of fabrication, strength, and ductility of CFST columns. Seventeen columns having varying geometric properties such as tube wall thickness, cross-sectional shape (circular, rectangular, and square), and slenderness were constructed and tested by applying load through both steel tube and concrete core. Circular columns were further distinguished by the presence or absence of main and hoop steel reinforcing bars in the core concrete. Axial load-displacement response, axial/transverse strain development, and failure modes were recorded during the loading history to analyze the performance. Experimental confined concrete strength and axial strength of UHSC-filled CFST columns were compared with those obtained from three suggested analytical models and three code-based design procedures including Eurocode 4, Canadian CAN/CSA S16, and American AISC. Analytical models were found to over-predict the confined concrete strength and the axial strength of CFST columns. Canadian and American codes were found to be most applicable for predicting axial strength of UHSC-filled CFST columns while remaining conservative. Full article

Infrastructure project delivery, specifically the delivery of water infrastructure projects, is a serious challenge in South Africa. Therefore, using the study context of water utility agencies in South Africa, the objective of this study was to examine the challenges that emanate from poor delivery and factors that cause poor delivery of water infrastructure projects in South Africa. Furthermore, it evaluated the various strategies that could enable improvement in water infrastructure project delivery. A survey research method constituting data obtained on the perceptions of relevant stakeholders and ordinal regression modeling were used for conducting the study. Findings suggest that delay in project completion, cost overruns, poor quality of work, poor fund utilization, and poor service delivery are the major challenges of the poor delivery of projects. The major factors that cause such challenges are linked to four aspects of the infrastructure projects such as project management, organization and management, construction and construction management, and sociopolitical. Six-pronged strategic measures, which include capacity building, the appointment of competent and skilled professionals, structuring review and monitoring processes, enhancing collaboration and communication among stakeholders, enabling accountability and transparency, and adopting participative leadership, can assist efficient water infrastructure project delivery in South Africa. Full article

The high wear resistance and toughness of electric arc furnace slag (EAFS) means that this industrial by-product can successfully replace natural aggregate in hydraulic or bituminous concretes that withstand vehicle traffic. This article validates the use of concrete made with large amounts of EAFS for rigid pavements. Accordingly, three EAFS–concrete mixes made with metallic or synthetic fibers were designed. Their performance was studied through laboratory tests (compressive strength, modulus of elasticity, splitting tensile strength, and abrasion resistance) and field observations on full-scale slabs made with each of the studied mixes. All mechanical properties yielded adequate results for concrete for rigid pavements. The metallic fibers increased the strength and elastic stiffness by 7–10%, while the addition of synthetic fibers slowed the development of these properties over time. On the other hand, all the mixes allowed for a successful implementation of full-scale slabs, with none of them showing excessive deterioration after five years of exposure to the outdoor environment. Only minor cracking and some chips in the surface-treatment layer were detected. The strength development of the slabs and their slipperiness were adequate for use in high-speed pavements. The overall analysis of the results shows that concrete made with EAFS can be used in real rigid pavements. Full article

Switch and crossing (S&C) faults are a major cause of track-related delays and account for a significant proportion of maintenance and renewal budgets for railway infrastructure managers around the world. Although various modelling approaches have been proposed in the literature for the simulation of vehicle–track dynamic interaction, wheel–rail contact and damage prediction, there is a lack of evaluation for combining these approaches to effectively predict the failure mechanism. An evaluation of S&C modelling approaches has therefore been performed in this article to justify their selection for the research interests of predicting the most dominant failure mechanisms of wear, rolling contact fatigue (RCF) and plastic deformation in S&C rails by recognising the factors that influence the accuracy and efficiency of the proposed modelling approaches. A detailed discussion of the important modelling aspects has been carried out by considering the effectiveness of each individual approach and the combination of different approaches, along with a suggestion of appropriate modelling approaches for predicting the dominant failure mechanisms. Full article

The ‘short’ neutral section is a feature of alternating current (AC) railway overhead line electrification that is often unreliable and a source of train delays. However hardly any dynamic analysis of its behaviour has been undertaken. This paper briefly describes the work undertaken investigating the possibility of modelling the behaviour using a novel approach. The potential for thus improving the performance of short neutral sections is evaluated, with particular reference to the UK situation. The analysis fundamentally used dynamic simulation of the pantograph and overhead contact line (OCL) interface, implemented using a proprietary finite element analysis tool. The neutral section model was constructed using physical characteristics and laboratory tests data, and was included in a validated pantograph/OCL simulation model. Simulation output of the neutral section behaviour has been validated satisfactorily against real line test data. Using this method the sensitivity of the neutral section performance in relation to particular parameters of its construction was examined. A limited number of parameter adjustments were studied, seeking potential improvements. One such improvement identified involved the additional inclusion of a lever arm at the trailing end of the neutral section. A novel application of pantograph/OCL dynamic simulation to modelling neutral section behaviour has been shown to be useful in assessing the modification of neutral section parameters. Full article