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Over the last 30 years, the last planner system (LPS), as a Lean-driven production planning and control tool, has consistently demonstrated its capability to improve planning reliability and overall performance in construction projects. Recent research provides evidence suggesting that the LPS ability to do good to projects has not reached its full potential yet. In fact, it has been observed that by identifying the missing social mechanisms in its implementation process and managing more effectively the complex socio-technical nature of the LPS, its implementation effectiveness is improved. However, commonly used research approaches, such as the case study method, have been criticized for lacking scientific control, replicability, and external validity. Alternatively, immersive virtual reality (IVR)-based simulation games have the methodological capability to enable the study of the social mechanisms that the LPS engenders when implemented in projects, by providing a highly controlled, reproducible, and ecologically valid experimental environment. However, how to leverage effectively IVR-based gaming technology to study the social mechanisms that the LPS engenders in construction organizations is not well understood. In order to bridge this gap, this paper established the conceptual and technical foundations to set IVR-based experimental environments and developed an IVR prototype encompassing nonlean and LPS-based rounds. The evaluation of the IVR prototype involved both quantitative and qualitative research approaches, focusing on its functionality, user-perceived presence and usability, task performance, and lean expert feedback. The results demonstrated the prototype's capability to create a controlled experimental environment while offering participants a user-friendly, immersive, and realistic LPS simulation experience. The contributions of this study are twofold: (1) the addition of a new method to the research methodology toolbox in construction engineering and management; and (2) the generation of design insights to develop IVR prototypes for research in construction engineering and management, and preliminary evidence for its ecological validity. [ABSTRACT FROM AUTHOR]

Steel through-truss is a very common configuration for railroad and highway bridges. There is a large number of such spans in surface transportation infrastructure worldwide, especially in railway systems. In design and evaluation, these spans' in- and out-of-plane bending have been either omitted or approximated. A fuller understanding of this effect will be able to assist in reliably designing and assessing these structures for longevity and/or increasing allowable service load to facilitate economic developments. A full scale load test is performed in this paper on five such bridges of the Canadian National Railway (CN) using train load. The main truss elements prone to in- and out-of-plane bending are identified and strain-gauged including the hanger (L1U1 or L'1U'1). Out-of-plane bending is seen to produce more significant flexural stress than in-plane bending. Three-dimensional (3D) numerical simulation is also verified by physical tests and covers other uninstrumented members of the tested spans. These results are used to evaluate the accuracy of a new and simplifying two-dimensional (2D) analysis method for the most significantly bent vertical hanger out-of-plane. The 2D method is shown to capture a significant portion of the bending but still underestimate flexural stress. An empirical and hybrid approach is therefore developed and recommended to address the inadequately accounted out-of-plane bending for routine practice of design and evaluation. It is needed when resources for detailed 3D analysis are not readily available, and/or when a quick and reliable method is needed, e.g., for verification or calibration of another method. These results are also useful for stress range estimation for fatigue analysis, although fatigue is not a concern to these bridges and is therefore not specifically addressed in this paper. CN has adopted the recommended method and the other research findings in load-rating their existing through-truss bridges. [ABSTRACT FROM AUTHOR]

In an effort to assist transportation professionals with the evaluation of wider economic benefits (WEB) of highway improvements, this paper provides important insights into the open-source AASHTO EconWorks wider economic benefits analysis tools using three case studies located in Indiana. The paper makes a significant contribution to the state of practice by providing an in-depth discussion of the lessons learned during the Federal Highway Administration (FHWA) implementation assistance program in Indiana. The paper briefly presents the theoretical background related to the development of the tools and explains data needs and sources. The discussion of the case studies primarily focuses on the sensitivity of the tools' results to critical input parameters (such as volume to capacity ratio and productivity elasticity), which has not been addressed in previous studies. Lastly, the paper elaborates on the applicability and limitations of the tools, and also discusses their potential integration into an agency's decision-making process. The inferences from this case study can be useful for state departments of transportation (DOTs), metropolitan planning organizations (MPOs), and other organizations interested in quantifying the potential productivity gains associated with planned or future highway projects. [ABSTRACT FROM AUTHOR]

This paper proposes a novel concept, stop-line setback (SLSB), aimed at enhancing the capacity of signalized roundabouts and solving the problem of unbalanced flow patterns. This method is believed to avoid wasting acceptable time gaps and therefore increase the capacity of the approach with SLSB. However, to the best of the authors' knowledge, no analytical work and little empirical work has yet explored the impact of SLSB. To bridge this gap, the phasing scheme and an adaptive control algorithm are developed for the roundabout with SLSB. Case studies are conducted under different traffic demands to evaluate the method. The findings show that (1) in peak hours the SLSB method is useful to improve the operational performance of the signalized roundabout and solve the problem of unbalanced flow patterns; (2) the right-turning vehicle volume is the critical factor that influences the benefits of the SLSB method; and (3) the phasing scheme and adaptive signal control algorithm developed in this paper are suitable to signalized roundabouts with distances of SLSB. Based on the aforementioned findings, it is recommended that the SLSB method be applied to one or two approaches with heavier traffic loads but not all approaches, which is believed to increase the capacity and reduce the average vehicle delay of the roundabout. [ABSTRACT FROM AUTHOR]

Land expansion and population growth are the most important factors for urban development in the rapid urbanization stage. Intensive land use is a key goal of urban sustainable development. Therefore, to promote intensive land use, local governments should take the scientific evaluation of the relationship between urban land and population as the basis and make policies cautiously. Thus, it is vital to adopt evaluation methods that are sensitive to intensive land use. However, this topic has received insufficient attention in the literature. Addressing this gap, this study (1) proposes a modified method to evaluate the relationship between land expansion and population growth, (2) compares the results of three evaluation methods, and (3) compares the relationship between evaluation results and urban construction land area per capita (UCAP) using UCAP as an indicator of intensive land use. Our findings indicate that existing evaluation methods do not adequately reflect the state and trend of intensive land use and that our modified model significantly improves the sensitivity to intensive land use. Additionally, this paper provides policy suggestions based on a quantitative evaluation of the relationship between urban land expansion and urban population growth. These conclusions provide a basis for formulating planning strategies to promote the intensive use of land in cities in the stage of rapid development. [ABSTRACT FROM AUTHOR]

Public participation as an alternative paradigm in planning theory is consequently a key challenge in planning practice regarding interactive and collaborative versus rational and top-down decision-making approaches. Hence, this paper aims to define this concept theoretically and then to evaluate it practically. Based on the relevant views and research, public participation has been considered through three main dimensions of "inclusiveness and incentive structures," "information exchange and provision of lay knowledge," and "sense of ownership and influence on decision-making." This threefold conceptualization has also been further explored by 10 subdimensions or measures to explain precisely the specific aspects of community participation. "Transparency and accessibility," "fairness or equal contribution," "effectiveness and efficiency," and "negotiation" are the most significant subdimensions. Thus, the concept of public participation has been evaluated in the Oudlajan market (Bazarcheh) in Tehran, where a supposedly participatory revitalization project has been implemented. This evaluation relies on the views of 117 market traders as respondents, using the analytical hierarchy process method. Accordingly, the overall status of the public participation in the Oudlajan project with a score of 2.56 based on a 5-point Likert-type scale is evaluated as between low and average. This finding implies that while the Oudlajan Market Revitalization Plan may seem participatory, it has serious shortcomings, especially according to the actual affected community or group. [ABSTRACT FROM AUTHOR]

This paper discusses advances in evaluation, health monitoring, and rehabilitation of cable-stayed bridges, and available methods. In the last 2 decades, the writer has contributed extensively to advances in cable-stayed bridge construction, design, and health monitoring. Information gathered from evaluation of the strength and reliability of dozens of stay cable systems worldwide, and health monitoring and inspection of more than 12 cable-stayed bridges in the United States and abroad, have discovered problem conditions that seem to be consistent across many types of cable-stayed bridges and stay cable designs, and have helped toward formation and evolvement of a unified approach for in-service evaluation and problem solving of these aesthetic structures. A case study related to evaluation and rehabilitation of the Luling Bridge in Louisiana, for which the new approach has been implemented almost entirely, is also described. The bridge evaluation process, and cable replacement design and its implementation, contain unique aspects and are the first attempted in North America. The cable replacement design accommodated an extraordinary construction sequence to address constraints on space and traffic flow. Temporary cables minimized stress variation and allowed for the live load without restriction. The new cable system allows individual strand installation and tensioning, and is expected to facilitate future inspections and replacement. [ABSTRACT FROM AUTHOR]

A system dynamics (SD) model was developed to identify the best road strategies for network-level maintenance and rehabilitation, considering technical, environmental, and economic grounds. This SD model uses triangulated research methods and data [e.g., interviews, policy analyses, and the VIZIR Pavement Distress Assessment Method (VPDAM)] to determine and allocate maintenance budgets in specific environmental and operational conditions. The system is tested via a case study at the Tunisian Radès Road Port (RRP). Baseline analyses of the simulation show the networked effects of key factors, including increased greenhouse gas (GHG) emissions, rehabilitation deficits, and climate change with reduced average pavement life. The SD model is calibrated and validated using data from RRP rehabilitation operations from 2020 until 2040. The model is coupled with an optimization module that recommends three optimal pavement solutions for the RRP and three pavement management systems (PMS) policies for improved sustainability. The model is based on sound technical principles, enhancing road function, sustainability, and cost savings. These findings contribute to the literature in PMS, SD modeling, sustainable development, and engineering management. [ABSTRACT FROM AUTHOR]

Cement-stabilized pavement layers are subject to sulfate attack (SA) in sulfate-abundant regions due to internal expansion–induced damage throughout its expected service life. SA is a coupled physical-chemical-mechanical damage process for cementitious materials involving complicated chemical reactions between sulfate and components of cement composite. SA contains intricate interactions among porous media, moisture transport, and heat transfer. Engineering mechanics has been used to explain the failure process of the internal expansion caused by this coupled physical-chemical ingress phenomenon. Existing studies have considered only heat transfer or moisture content–dependent modeling. The literature lacks a comprehensive model that considers coupled interaction of temperature and humidity upon sulfate ingression. Thus, a chemomechanical (CM) model has been developed for capturing the true failure process of cement-stabilized pavement subgrades under SA. In this paper, a set of governing equations are developed, and a unique expression for a moisture-dependent and heat-dependent sulfate diffusion coefficient is proposed. Consequently, the equations are solved using the finite-element method. The results conform well with experimental results. The model has been validated to be accurate enough compared with previously implemented models. It is capable of evaluating and predicting SA-induced expansive failure in unsaturated cement-stabilized pavements. Two different models were combined to estimate the mechanical behavior of cement-stabilized subgrades subject to SA. Finally, the Drucker-Prager (DP) failure criterion was used for determining the damage zone. [ABSTRACT FROM AUTHOR]

The interface bond strength between carbon fiber-reinforced polymer (CFRP) layers and concrete is a crucial metric for determining the mechanical properties of CFRP-reinforced concrete. This bond strength is essential for evaluating CFRP-reinforced concrete's performance and ensuring the materials' structural integrity. A database was established using the experimental data in the literature to evaluate the interface bond strength. This database comprised 360 groups of different conditions test results of CFRP-reinforced concrete, which were used to create a prediction model using an artificial neural network. The database was randomly divided into two data sets: 310 groups were used for training the neural network model and 50 for simulated prediction. A three-layer artificial neural network model was trained using the backpropagation algorithm, which is widely used in artificial neural networks. The model's input layer considered seven parameters, including the type of CFRP layer, surface form, CFRP layer thickness, anchorage length, failure mode, concrete compressive strength, and normalized concrete cover thickness. These parameters were selected based on their known influence on the interface bond strength between the CFRP layers and concrete. The output layer of the model represented the interface bond strength between the CFRP layers and concrete. The model's results indicated that the backpropagation (BP) neural network model had strong capability of prediction and generalization. The predicting error was minimal, a crucial aspect of the model's accuracy. Further, this approach allows for integrating many factors that influence the interface bond strength between the CFRP layers and concrete, providing accurate predictions of the bond strength. It can be used as a valuable tool for evaluating the performance of CFRP-reinforced concrete. This research develops an accurate method to predict the bond strength between CFRP layers and concrete using artificial neural networks. A strong bond is crucial for the structural integrity of concrete reinforced with CFRP. The neural network model considers factors like the type and thickness of CFRP used, how the concrete surface is prepared, and the concrete's strength. Engineers can use this neural network tool to evaluate how well CFRP will reinforce specific concrete mixtures and structures before construction. This allows structures to be designed and built with optimal, cost-effective use of CFRP to reinforce concrete in applications like bridges and buildings. The neural network approach integrates many technological and material factors into one predictive model, providing a useful evaluation method for the construction industry. [ABSTRACT FROM AUTHOR]

Scaling, erosion, and cracking are some manifestations of deterioration of concrete surfaces due to chemical attack, exposure to cyclic freezing and thawing, and so forth. Though a rating of the surface can be done visually using some standard method, such an evaluation still remains largely qualitative and subjective. For laying down specifications and maintenance of structures, quantitative and objective methods are required to assist objective decision-making. This paper reports the results of the application of a modified version of a test procedure that is used to determine the surface texture of pavements using concrete specimens subjected to accelerated deterioration due to cyclic freezing and thawing. It is found that the test can be used in conjunction with others to maintain an objective and quantitative record of deterioration of surface characteristics. The fact that the test is nondestructive, noninvasive, and requires only minimum training of workers and simple tools, makes the proposition of using this test more attractive. A possible classification that can be used for specification writing and maintenance of structures is also suggested. [ABSTRACT FROM AUTHOR]

The new ASCE Vision and Body of Knowledge embraces the attitude toward and skills of lifelong learning, indicating the need of acquiring self-regulated learning (SRL) skills. Although civil engineering education has primarily focused on instilling technological knowledge to students, less attention has been paid toward offering deliberate training for nurturing such required high-order skills based on how people learn. This paper introduces the theoretical construct of SRL and the effective pedagogies of cultivating SRL skills from educational research findings, presents a novel instructional framework and its procedures to support students' SRL skill development, and reports its implementation outcomes in civil engineering curricula at a minority-serving institution. The key instructional strategy is to integrate the prompted self-assessment with the course learning tasks into the students' learning processes. Its effect has been evaluated through the feasible assessment practice. Assessment results reveal that the presented framework may benefit students' learning performance, and the majority of students perceived the importance of SRL skills and were interested in developing SRL skills. The limitations of this study and future improvement are also discussed. [ABSTRACT FROM AUTHOR]

A successful civil engineering project is often a highly collaborative team-based activity, and the engineering education community must therefore prepare graduates to work in this type of environment. A large body of research has demonstrated the considerable benefits and minor organizational problems of collaborative work in higher education. However, there are only a few case studies reported in the literature that evaluate the positive and negative experiences encountered by students when undertaking group projects, and these invariably focus on first-year students. This paper contributes to this limited literature by assessing previously existing methodologies applied to group projects in the final year of an engineering degree, and compares the results with those obtained for students with no experience in collaborative work. The methodology was tested on a survey sample of 105 students enrolled in the Roads module of the new Civil and Territorial Engineering degree at the Technical University of Madrid (UPM). Although the results highlight the extremely positive effects of group projects on the students' perceptions, certain deficiencies were also detected relating to the lack of previous collaborative work in the students' background, an area which requires further research [ABSTRACT FROM AUTHOR]

All over the world, governments, policy makers, and practitioners are searching for proper routes and corridors to invest transportation infrastructures such as new railways, highways, and multimodal ways. Although it is one of the important steps of development, finding a suitable route for new transport infrastructure is a complicated and conflicting task for of various reasons. Possible social and environmental impacts on society and increasing cost and technical pressures on decision makers are some of these reasons. Taking into consideration aspects of different evaluation criteria, a geographic information system (GIS)-based multicriteria solution approach is proposed in this study. Potential high-speed rail (HSR) routes in Turkey are considered as a case study. After gathering and processing the related GIS data, weights are assigned to each criterion by using the fuzzy analytic hierarchy process in order to indicate their relative importance. Then, the additive ratio assessment method is applied to carry out the multicriteria (13 technical, social, and demographic criteria) evaluation and selection of the suitable alternatives (among 20 HSR routes) under given circumstances. It was found that the corridor from the west part of Turkey (from İzmir and Manisa) to the Marmara region (Kocaeli and İstanbul) had the highest priority, followed by the corridor from Ankara to Kayseri. HSR trains could potentially reduce the journey times to Kocaeli and İstanbul from İzmir and Manisa, as compared with driving, by 46% and 45%, respectively. The results of this study can be used to evaluate potential HSR corridors/routes or similar transport infrastructures in other countries. [ABSTRACT FROM AUTHOR]

Highway traffic loads and environmental conditions, including temperature and moisture at the layer interface, could cause debonding or delamination between adjacent asphalt pavement layers in tensile, shear, or mixed-mode failures. Thus, studying the tensile and shear strengths of interface bonding is crucial to maintaining durable and functional pavement structures. The main objective of this research is to evaluate and estimate the interface bonding strength (IBS) between asphalt pavement layers under the mixed shear-tension loading mode. To this end, an experimental, statistical, and machine-learning (ML) approach was adopted. A total of 164 double-layered hot-mix asphalt specimens consisting of hot-mix asphalt AC-13 in the upper layer and AC-20 in the lower layer were tested via a direct tensile device with a supplementary shear fixture. The effects of test temperature, shear stress, and tack coat application rate on the IBS were considered. The results revealed that with increasing tack coat dosage, the IBS peaked at 0.8 kg/m2 and was subsequently decreased. It was also found that the IBS was very sensitive to temperature changes and heavily dependent on shear stress at elevated temperatures. On the other hand, with increasing shear stress from 0 to 0.20 MPa, the IBS at temperatures of 5°C, 20°C, and 35°C declined by 10.96%, 61.85%, and 83.16%, respectively. Two prediction models for the IBS based on the conventional statistical models of multiple linear regression (MLR) and nonlinear regression were successfully developed. However, the nonlinear model outperformed with a better prediction accuracy of 24.2% compared with linear regression (R2=71.8%). Finally, a highly accurate feed-forward back-propagation (FFBP) artificial neural network (ANN) model was developed to predict and form a relationship between the IBS and independent variables with an extremely low margin of error. It was revealed that the developed FFBP-ANN model could capture 99% of the measured data. Finally, a comparative analysis demonstrated that the developed FFBP-ANN model was superior to regression modeling in terms of predicting the IBS. [ABSTRACT FROM AUTHOR]

This paper demonstrates the analysis of the relative deterioration trends of the various types of bridge structural design and/or construction to determine and compare their operational structural performances at the serviceability limit states. The study derives operational data from the entire database of the U.S. National Bridge Inventory and analyzes the actual bridge deck areas rather than bridge counts. Deck areas more realistically reflect the actual sizes of bridge types, enabling a more reliable analysis of deterioration trends and providing more objective structural performances. The study analyzes the trends of the proportional accumulation of deterioration by bridge type, considering criteria based on the concept of structural deficiency and the objective of life-cycle expectancy for uninterrupted service life. The multiple-criteria diagnostic approach integrates the rate and pattern performances, based on deterioration trends, with the condition, durability, and longevity performances to determine and compare the overall equivalent structural performances using prioritized weights. As compared to inventory averages, the results reflect the distinct deterioration trends of bridge types and show a decrease in the equivalent structural performances by 10%. As compared to counts, the equivalent structural performances by areas are lower by 3% for all bridge types and 34-40% for some bridges. Also, the annual maximum average accumulation of structural deficiency of all bridge areas is nearly 20% lower than by counts. The average increase in structural deficiency is 0.42% per year, adding to the already existing 9.38% and constituting an average annual increase of structurally deficient (SD) bridge areas by 4.48%. The analysis also identifies premature accelerated accumulation of deterioration for a particular age group within a bridge type, indicating a critical need to investigate the etiology of the deterioration and improve existing and future bridges. The study provides a comprehensive national network-level comparative experience of the operational structural performances of bridge types by area under actual practices and circumstances to help identify critical deterioration, forecast future structural performance, and promote the sustainability of bridge types. [ABSTRACT FROM AUTHOR]

The determination of suction-water content relationship (SWR) is of prime importance in unsaturated soil mechanics. When such a relationship is obtained from continuous drying or wetting process of the same soil sample, it is termed as water retention characteristic curve (WRCC). The relationship obtained from suction measurement of remolded soil samples with different water content is termed as spot SWR (SSWR). Most of the reported studies use drying WRCC (DWRCC) because of the relative ease of its measurement as compared to wetting WRCC (WWRCC). There are not many studies that critically compare measured DWRCC, WWRCC, and SSWR of soils. Such a comparison would help to understand the differences in WRCC attributable to hysteresis and limitations of spot measurements, if any. A simple procedure similar to the field wetting process is discussed in this paper for developing DWRCC andWWRCC on the same soil sample, one after the other. WRCCs and SSWRs of three cohesionless soils are not unique for the range of suction measured in this study. The implication of such nonuniqueness is further investigated by comparing unsaturated soil hydraulic conductivity function estimated based on WRCCs and SSWRs. [ABSTRACT FROM AUTHOR]

This paper investigates the evaluation procedure of an AASHTO Type 3 precast-prestressed girder that was extensively damaged by truck impact and then repaired using externally bonded fiber-reinforced polymer (FRP) composites. Results of this study can be applied to bridges having similar vehicle impact incidents. Parameters whose effects were investigated on the evaluation procedure include (1) the effect of horizontal resistance of elastomeric bearing supports, (2) the presence of barrier wall and sidewalk, and (3) live load distribution factors obtained from finite-element analysis (FEA) compared with the simplified method prescribed by other codes. FEA showed that support horizontal resistance has negligible effects on live load distribution factors for shear, Fm, while it has considerable effect on live load distribution factors for moment, Fm. The live load distribution factors Fm and Fv calculated from the simplified method of analysis prescribed by other codes were observed to all be greater than those obtained from FEA, showing that the approach taken by other codes is conservative for the studied bridge. The Fm and Fm of external girders obtained by FEAwere as much as 30 and 40% less than those of other codes. Inclusion of barrier wall and sidewalk in the analysis showed an additional 18% reduction for Fm, with insignificant effect on Fm. The live load capacity factor as the safety indicator in the bridge evaluation was calculated analytically by the load and resistance factor method and the mean load method and then correlated with experimental findings of proof load test on the repaired girder. [ABSTRACT FROM AUTHOR]

Slender monumental stairs are major architectural features in many high-end building structures. Architectural requirements for these are usually very aggressive, with long spans and slender stringers being the norm. The resulting low natural frequencies are often within reach of the lower harmonics (which have high amplitudes) of the vertical force caused by a person descending the stair. Also, some configurations with very low frequency lateral vibration modes might allow high lateral accelerations. Because the potential for annoying vibrations is high, it is critical that stair designers have access to evaluation methods. Current evaluation methods rely on finite-element analysis-based response prediction methods that are outside the reach of many structural engineering firms. This paper presents a simplified vertical acceleration prediction method, based on the fundamental natural mode of the stair, which is suitable for manual calculations. Response predictions are compared to experimental measurements to calibrate the prediction method for design use. Lateral vibrations are discussed, and an evaluation method is proposed. Finally, a numerical example is provided. [ABSTRACT FROM AUTHOR]

One of the most important parts of any bridge management system is the condition assessment and rating of bridges. This paper introduces a procedure for condition assessment, based on criticality and vulnerability analysis. According to this procedure, new rating equations are developed. The inventory data are used to determine the contribution of different critical factors such as environmental effects, flood, earthquake, wind, and vehicle impacts. The criticality of the components to live load and vulnerability of the components to the preceding critical factors are identified. Based on the criticality and the vulnerability of the components and criticality of factors, and by using the new rating equations, the condition assessment and the rating of the railway bridges and their components at the network level will be conducted. This method, for the first time, incorporates structural analysis, available knowledge of risk assessment in structural engineering standards, and the experience of structural engineers in a practical way for enhancing the reliability of condition assessment for rating a network of bridges. [ABSTRACT FROM AUTHOR]

This paper describes a technique for evaluating the impact of climate change on drinking water treatment operations and for applying engineering principles to minimize those impacts. The U.S. Environmental Protection Agency (USEPA) Water Treatment Plant model was modified, validated, and applied to a case study based on the Greater Cincinnati Water Works' Richard Miller treatment plant to provide quantitative measures of these impacts. Multivariate Monte Carlo experiments were executed to simulate and track performance of the Miller plant subject to nine jointly distributed source water quality parameters under both current and potential future hydrologic conditions. Results from the case study indicate a risk that finished water may exceed critical total organic carbon (TOC) levels, leading to potential violations of disinfection by-product regulations under plausible future scenarios. The future risk, however, can be managed with operational adjustments at the water treatment plant, such as increasing the frequency of granular activated carbon reactivation. Utility costs associated with the operation adjustments were expressed as cost curves. The approach presented in this paper can be useful for evaluating climate change impacts and for planning infrastructure and operational adaptation. [ABSTRACT FROM AUTHOR]

In designing and evaluating roadway bridges in the surface transportation infrastructure, truck load is a major variable to account for. For daily operation, truck load also is a primary factor. Trucks on continuous spans were studied, with a focus on their behavior of longitudinal multiple presence in the same lane(s). Current US specifications include provisions for how to account for such multiple presence, and these provisions have evolved over the years. However, the basis for the provisions and their changes have not been well documented. An unprecedentedly large number of high-quality in-motion truck weight data were gathered in eight states across the US and used to investigate trucks' longitudinal multiple presence behavior. A new approach to analyzing each platoon of trucks recorded in traffic was developed for this purpose. Each random platoon's total load effect was identified, covering every truck in the platoon, to obtain reliable statistics of the maximum load effects. Results show that longitudinal multiple presence increases with truck volume and span length. Relevant current AASHTO provisions therefore were found to be conservative or overconservative. Accordingly, it was concluded that lower longitudinal multiple presence factor values for evaluation and design are more justifiable. These results may be used by bridge owners and engineers for realistic load rating and design, for more-uniform structural safety and cost effectiveness. This is consistent with the top two goals of the AASHTO Committee on Bridges and Structures' strategic plan for extending bridge service life and assessing bridge condition. [ABSTRACT FROM AUTHOR]

Reinforcement bars in concrete are exposed to several actions, such as overloading, fatigue, and corrosion. These actions can lead to a deterioration of the reinforcement bars. However, only advanced stages of damage in the reinforcement will be visible at the surface. Since no suitable commercial nondestructive methods are available yet, the concrete cover must be removed if damage is suspected. The magnetic flux leakage method is a promising approach to solving this problem. A measuring device was developed that enables the simultaneous magnetization of the reinforcement and measurement over a width of 20 cm. To support the user, a software is in development that allows for immediate evaluation and interpretation of the results. The present project aims at demonstrating the value of the magnetic flux leakage method in particular for bridge evaluation. [ABSTRACT FROM AUTHOR]

This paper demonstrates the analysis of the deterioration trends of the various types of bridge structural design and/or construction in the entire U.S. National Bridge Inventory, to derive and compare operational structural performances. The approach considers the trends of the proportional accumulation of deterioration by bridge types, based on the concept of structural deficiency and the objective of life-cycle expectancy at the serviceability limit states. The analysis determines the rate and pattern of the deterioration trends. The multiple-criteria diagnostic approach integrates the rate and pattern performances with the condition, durability, and longevity performances to determine the overall equivalent structural performances using prioritized weights. This study produces the most comprehensive national network-level comparative basis of the operational structural performances of bridge types under the actual circumstances. The deterioration trend performances of most bridge types are relatively lower. Also, the overall equivalent structural performances of almost all bridge types are lower. The analysis also helps identify critical accumulation of deterioration for bridge types, suggesting focused improvement efforts necessary for existing and future bridges. The most common stringer/multibeam or girder bridges have relatively higher and faster accumulation of deterioration, generating a below average trend and equivalent structural performances. The results help predict future performances and improve effectiveness of bridge types for sustainable service life. [ABSTRACT FROM AUTHOR]

Infrastructure networks are essential to support the world's economic development. Governments around the world, in both developed and developing economies, have dedicated significant shares of the public budget to infrastructure development and refurbishment. Nevertheless, there has been an increasing concern about the selection of economically more interesting projects. The large sunk investments, as well as the uncertainty surrounding these projects, require new and more sophisticated investment analysis techniques. Simultaneously, there has been a recent trend towards increasing the flexibility in these projects to allow a more progressive adaptation to changing market conditions, thus decreasing the overall risk affecting these investments. The flexibility is introduced through real options that include the possibility of change that one develops in the planning and design stage, allowing the infrastructure (and service) to cope with future uncertainty. This paper intends to provide an overview of the current literature on real options, thereby fulfilling a gap in current academic literature. It addresses the main types of options and valuation mechanisms and provides an extensive overview of their application to the infrastructure sector. [ABSTRACT FROM AUTHOR]

Low-density urban sprawl is reducing the quality of urbanization, especially in China. Improving the population aggregation degree is an essential means to solve the problem, and in this process, the central urban area plays a vital role. It is necessary to explain the population's spatiotemporal distribution mechanism and analyze the potential of population aggregation. The study took the central area of Tianjin, China, as an example, and the working framework focused on the comprehensive perspective of the urban built environment, which was divided into four dimensions (spatial construction intensity, spatial function characteristic, spatial accessibility, and spatial ecological quality). A geographically and temporally weighted regression (GTWR) model was first applied to determine the spatiotemporal relationship between the urban built environment and population-density distribution, and then, an urban-population aggregation-potential evaluation model was constructed through bivariate local spatial autocorrelation to analyze the potential for population aggregation. The results showed that spatial construction intensity and function characteristic indicators had the most significant impact intensity and were the main influencing factors, with spatial accessibility and spatial ecological quality indicators as subsidiary factors. Each index had the heterogeneity of influence in both time and space simultaneously, which was manifested in the spatiotemporal nonstationarity of the correlation coefficient. Most of the high-population aggregation-potential areas in the study were single-type high-potential areas, accounting for 37.78%, and were dominated by building density. Based on the mechanism and potential results of population spatiotemporal aggregation, the study provided new planning advice for Chinese cities to achieve better space utilization and sustainable urban development. [ABSTRACT FROM AUTHOR]

29Si and 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy techniques were employed towards evaluation of hydrated cement paste and concrete subjected to accelerated sulfate attack. Quantitative analyses of the 29Si NMR spectra of specimens subjected to different periods of sulfate attack indicated that the chain length CL of SiO4=AlO4 tetrahedra was lowered by sulfate attack. 27Al NMR spectra indicated that sulfate attack produced a significant rise in the intensity of ettringite and a sharp drop in the concentration of monosulfate hydrate, which are some primary indications of sulfate attack on concrete. Fourier-transform infrared (FTIR) spectroscopy method was employed in order to verify the result of NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Residents of northern Tehran are well paid and have better access to urban services, whereas their southern counterparts are paid less and deprived. Land value also differs significantly between the north and south. However, it seems that having more apt objective indicators does not necessarily lead to an enhancement in subjective indices. The hypothesis is that "Justice is not perceived at a higher level among the dwellers of the higher-income quarters of Tehran compared with their counterparts in the lower-income quarters." To test this hypothesis, we attempted to define the criteria of justice, as perceived by Tehran citizens. According to previous studies, Tehran citizens generally perceive justice through four criteria: reduction of the gap between the poor and rich, government's assistance to the poor, law enforcement, and absence of corruption. Based on these criteria, justice is evaluated in Niavaran (a high-income quarter in northern Tehran with good access to urban services) and NematAbad (a low-income southern quarter with poor services) via a questionnaire (a randomly selected sample of 200 people). The results show that despite the existing objective differences between the infrastructures, services, and incomes, there is no significant difference between these quarters in terms of the perceived (subjective) justice (based on Mann–Whitney U test). The citizens in both quarters are dissatisfied with the status of all criteria. It is concluded that only physical strategies and enhancement in city services have not been accountable for the promotion and a sense of justice. Thus, the attention of planners should shift from physical indicators to mental indicators. [ABSTRACT FROM AUTHOR]

Explicit prediction of the suspended sediment loads in rivers or streams is very crucial for sustainable water resources and environmental systems. Suspended sediments are a governing factor for the design and operation of hydraulic structures, like canals, diversions and dams. In recent decades, to model hydrological phenomena which are complex in nature the machine learning models are used commonly. In the present study, support vector machine (SVM) with wavelet transform (WASVM) has been employed for prediction of daily suspended sediment load (SL) for two south Indian watersheds (Marol and Muneru) using hydrometeorological data. A 40-year daily observed data (1972-2011) have been used for the analysis, where past SL, streamflow (Q), and rainfall (R) data were used as the model inputs, and SL was the model output. Using conventional correlation coefficient analysis between input and output variables, the best input of WASVM model was identified. The reliability of SVM and WASVM models were evaluated on the basis of different performance criteria, i.e., coefficient of determination (R²), root mean square error (RMSE), normalized mean square error (NMSE), and Nash-Sutcliffe coefficient (NS). Initially, 1-day ahead SL prediction was performed using the best WASVM model. The results showed that, 1-day predictions were very precise, showing a close agreement with the observed SL data (R² = 0.94, NS = 0.94 for the Marol watershed, and R² = 0.77, NS = 0.77 for the Muneru watershed) in the testing period. The same WASVM model was then used for the prediction of SL for the higher lead periods. The NMSE value for the Marol watershed was found as low as 0.06 for 1-day ahead prediction, and increases subsequently as 0.29, 0.46, and 0.70 for 3-, 6-, and 9-day higher leads, respectively. Likewise, for the Muneru watershed, the NMSE value was found as low as 0.21 for 1-day ahead prediction, and increases subsequently as 0.42, 0.53, and 0.68 for 3-, 6-, and 9-day higher leads, respectively. Further, the model was evaluated on the basis of its capability of predicting peak SL and cumulative SL for 1- to 6-day leads. The statistical analysis shows that the developed WASVM model can predict the target value successfully up to a 6-day lead and is not suitable for higher lead specifically in the selected watersheds having similar hydroclimatic conditions like the ones selected in this study. Predictions by the WASVM model were found significantly superior to the ones obtained by the conventional SVM model. The results revealed that the WASVM model provides a very good accuracy in predicting SL and can be used as an effective forecasting tool for hydrological applications. [ABSTRACT FROM AUTHOR]

Integrated design (ID) process encourages integration of team members in the design phase of green building projects through intense collaborative processes and free exchange of information. Although integration in general and ID in particular have been well theorized by construction management research community, there exists no systematic mechanism in the field to help owners, architects, and managers of green project teams assess the level of integration in their projects' ID team environment in a practical manner. The key objective of the present article is therefore to use a qualitative-quantitative methodology to propose and validate an integration evaluation framework for green project teams and to statistically test the association between integration level and project success. The framework can be used by green project teams for comparison, benchmarking, or educational purposes and for integration evaluation and improvement in ID team environments. This research also provides empirical evidence to anecdotes suggesting positive link between team integration and project success in green projects. [ABSTRACT FROM AUTHOR]

Information technology (IT) has increasingly been highlighted in the construction industry as an integral contributor in improving project performance and competition. IT application challenges for infrastructure operation companies still exist creating a need for improved evaluation methods of information systems (IS) prior to application. This study proposes a scheme for evaluating IS from both functional and nonfunctional aspects at the maintenance management process level. Considering the characteristics of maintenance management processes, discrete-event simulation coupled with the Keystroke-Level Model is adopted in the scheme. A case study is conducted using the scheme, and results reveal that IS is positively associated with maintenance performance. The effects of IS of varying levels on different processes and users are determined based on the functions within the organization. Moreover, the obstacles that hinder favorable user experiences of IS are identified. The case study verifies that the effects of IS on maintenance performance can be assessed quantitatively and objectively through application of the scheme. Decision makers may apply the scheme in the IS planning phase or in optimizing the available IS. [ABSTRACT FROM AUTHOR]