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The partnership between the public and private sectors has led to a new and innovative way of delivering infrastructure projects that is referred to as public–private partnership (PPP). There are various benefits associated with PPP delivery methods including risk sharing, access to private funding, innovation, and flexibility, among others. Despite the proved benefits, contract conflicts and disputes are very common in PPP projects. While previous research studies examined the risks and the potential causes of conflicts in PPP projects, little-to-no research efforts were directed to study and model the interconnectivities between the different causes of conflicts in PPP agreements. To this end, the aim of this paper is to fill the gap in knowledge by providing a deeper understanding of the causalities or relationships between the different factors that cause disputes in PPP projects in the United States. The authors used a comprehensive analytical approach that involved three primary steps. First, 37 PPP case studies of infrastructure and construction projects were collected and analyzed using manual content analysis. Second, social network analysis was conducted to study the interdependencies between the different causal factors leading to disputes in PPP in general and in relation to Execution, Investment and Operation, and Third-Party Claims, in particular. Third, association rule analysis was conducted to identify key associations between the different causal factors that may trigger the three different types of PPP disputes. The findings showed that the key causes of disputes in PPP projects are related to (1) legal and regulatory, (2) payment and financial, and (3) poor management. While Execution-related disputes were found to be caused by complex interactions of causal factors, dispute causation of Investment and Operation–related and Third-Party Claims–related disputes seemed to be less simplistic. As such, the outcomes of this paper highlighted the important aspects required to avoid dispute occurrence in PPP projects. Ultimately, this paper contributes to the body of knowledge by providing directions for scholars and practitioners toward the aspects and interdependencies that require optimization and/or thorough consideration to avoid dispute occurrence and subsequently ensure successful implementation of PPPs. [ABSTRACT FROM AUTHOR]

The increasing availability of bridge data from the National Bridge Inventory (NBI) offers a great opportunity to perform predictive analytics (such as bridge deterioration prediction) using machine learning (ML) pipelines for supporting bridge asset management. However, data quality issues (e.g., outliers and missing values) can significantly affect ML pipelines, requiring upstream tasks to be performed for ensuring the validity, applicability, and generalizability of pipelines. Among the tasks, outlier removal and missing value imputation are the most challenging due to a highly laborious process, a lack of data governance, and a mixture of heterogenous data quality issues and data types. To address this challenge, this paper proposes an upstream workflow for enhancing the downstream predictive analytics of bridge-related ML pipelines. The proposed upstream workflow was developed based on the NBI data collected for all States in the United States, which includes a total of 617,084 observations/bridges. Existing bridge domain knowledge from multiple sources (such as the bridge design manual and regulations) was leveraged to remove outliers. Then, this study applied and compared 10 statistical and ML-based data imputation techniques to impute missing values. Statistical analysis and imputation evaluation of NBI data indicated that: (1) 19 and 15 out of the total 38 frequently used features or variables had outliers and missing values, respectively; (2) categorical features are generally more prone to data dropping due to inapplicable values, while numeric features are more subjected to outliers; and (3) ML-based data imputation is more suitable than statistical imputation for both numeric and categorical features, especially for features with high missing rate. The proposed workflow was validated on its capability of improving downstream predictive analytics for bridge deck condition prediction, increasing the balanced accuracy by 6.85%–9.76%. This paper contributes to the body of knowledge by offering a novel upstream workflow that can be utilized as a benchmark for guiding researchers and bridge engineering practitioners to handle NBI data quality issues for better preforming predictive analytics using ML pipelines. [ABSTRACT FROM AUTHOR]

There are multiple dam failures and dam safety incidents every year in the United States. There are currently no standard policy requirements for when or how to conduct failure or incident investigations. In order to understand the state of the industry, this study reviewed 58 different dam failure or incident investigation reports based on incidents that occurred in the United States from 1960 through 2022. The investigations ranged from well-known failures/incidents of large dams such as Oroville Dam and Teton Dam, to little known structures such as Hawkins Dam, a small dam in the state of Washington that had a spillway failure in 2014. The investigations were analyzed and evaluated for characteristics such as the length of time for the investigation team to get on-site, the amount of time to complete the full investigation, what organization funded the investigation, independence of the investigation team, scope of the investigation, and several other parameters. Based on the analysis, investigations after the year 2000 have seen more time pass before the investigation team can visit the site and investigations have taken longer to complete. Investigations are often not fully independent, are most commonly funded by federal agencies, and often do not investigate human, programmatic factors, or consequences. This paper makes 10 recommendations for improving investigations in the future, including recommended definitions for incidents and failures. In this paper, the authors recommend that (1) a dam safety incident be defined as a potential failure mode has initiated and progressed but has not led to an uncontrolled release from the reservoir; (2) a high flow release be defined as: An incident when there are consequences downstream of a dam due to controlled flows passed by the dam, not due to the failure of a dam or dam component; and (3) that dam failures be separated into three types based on the severity of downstream consequences. [ABSTRACT FROM AUTHOR]

This paper reviews the state of the art in using benefit–cost analysis (BCA) to inform earthquake risk reduction decisions by building owners and policymakers. The goal is to provide a roadmap for the application and future development of BCA methods and tools for earthquake risk reduction. Our review covers three earthquake risk reduction measures: adopting up-to-date building codes for new construction, designing new buildings to exceed code requirements, and retrofitting deficient existing buildings. We highlight the factors that influence the cost-effectiveness of building design and retrofit, as well as tactics for increasing the cost-effectiveness of risk reduction strategies. We also present BCA results, methods, and data sources used in the literature to help researchers and practitioners design and conduct a reliable and robust BCA study. In the process, we develop a set of opportunities and challenges for applying BCA to new areas of research, as well as key gaps and limitations in current BCA approaches, including further investigation of above-code design, incorporation of code implementation and enforcement into BCA, quantification of environmental benefits of seismic retrofits, and optimization of seismic retrofits with energy upgrades. Overall, our review provides practical guidance and useful insights into BCA with the goal of increasing the earthquake resilience and economic efficiency of buildings in the United States. [ABSTRACT FROM AUTHOR]

Investments in the architectural, engineering, and construction (AEC) sector can be used by governments to introduce desired changes in the economy, which gives an indication of the future trends of the economy. In addition, the stock market—as reflected by the Standard and Poor 500 (S&P 500)—creates a sense of confidence about the direction of the US economy. Many studies have shown that stock prices in multiple international industries could be considered as leading economic indicators. Nevertheless, this was not researched within the AEC sector in the United States. This paper addresses this knowledge gap by investigating whether the stock prices of AEC companies in the United States could be used to inform strategic, proactive decision making. First, time series data were collected for the stock prices of 16 large AEC companies as well as for the S&P 500 index. Second, multivariate time series analysis was conducted to examine the type of relationship between the response variable—S&P 500—and all other input variables. Two econometrics models were developed: a linear, statistical vector autoregression model and a computational, deep learning model based on long–short-term memory (LSTM) networks. Third, the two developed econometrics models were tested on unseen data. Fourth, the best econometrics model was verified using another leading economic indicator which is the Purchasing Managers' Index. The results reflected that the computational LSTM model outperformed the linear statistical model. The findings showed that the stock prices of AEC companies could be considered as an additional and complementing leading economic indicator to the American Institute of Architects' Architecture Billings Index to provide a broader perspective of the business ecosystem. This paper adds to the body of knowledge by providing an econometrics model for helping in optimal investment opportunities, taking informed strategic management and business judgments, and predicting changes in the economy. [ABSTRACT FROM AUTHOR]

Recent amendments to design ground snow load requirements in current US standards have reduced the size of case-study regions by 91% from what they were in previous standards, primarily in western states. This reduction is made possible through the development of highly accurate regional generalized additive models (RGAMs), stitched together with a novel smoothing scheme implemented in the R software package remap, to produce the continental-scale maps of reliability-targeted design ground snow loads available in current standards. This approach allows for better characterizations of the changing relationship between temperature, elevation, and ground snow loads across the conterminous US (CONUS). RGAMs are shown to have 10% or better improvement in mean absolute mapping error in two independently created data sets when compared with traditional mapping techniques. Structures must be able to withstand environmental stresses without collapsing, including snow. Design ground snow loads are estimated using snow measurements taken at weather stations throughout the US. Mapping techniques allow design ground snow loads to be estimated at regions between weather stations. This paper describes a regional approach for mapping design ground snow loads in CONUS and demonstrates the improved accuracy of the approach, relative to previous methods, on two independently created national data sets. [ABSTRACT FROM AUTHOR]

Since the 1800s, there have been live load surveys and analyses carried out, particularly of area-dependent loads in office buildings. While some occupancies have received careful examination, there has been no systematic review and consideration of reliability-based scenarios for office gathering space live loads. The results of the research reported here indicates (supports) a more consistent, reliable, and economic design load for office gathering spaces in buildings. These results provide the theoretical and practical basis for design live loads for gathering spaces within offices, a step toward possible enactment in the current standard, and subsequently by adoption into the International Building Code and materials standards. Following a review of historical load surveys and theoretical models, the paper presents models and observations of crowding, serving as a basis for a different approach for such areas, including a Delphi among leading design firms in the United States. The paper concludes with recommendations for a new live load use category for gathering spaces for offices. Modern office usage often contains work spaces for meeting, gathering, and collaboration. The current standard for minimum design loads and associated criteria for buildings and other structures does not directly address this situation. Interpretation has led to conflicting requirements for the design loads of such spaces, including the possibility of assigning them as assembly areas. This can lead to overdesign and uneconomical structures. This research reviews historical office surveys with an emphasis on assembly spaces, presents the results of a Delphi of design firms throughout the United States, and contains a stochastic maximum load analysis. These various assessments lead to a consistent evaluation of plausible loads for such spaces, and a recommendation for a new subcategory in the standard live load table. The study recommends treating these spaces similar to general offices, with a basic live load of 2.39 kN/m2 (50 psf), and permissible live load reduction as is currently in the standard for offices. Exception is made for such work spaces that are directly accessible from outside and intended for use by the general public. [ABSTRACT FROM AUTHOR]

The load resistance (LR) of glass lites is determined in the United States by use of standards based on a probabilistic model of glass breakage. These standards generally restrict design to rectangular glass lites continuously supported along one, two, three, or four sides. In addition, these standards treat single glass lites as simply supported flat rectangular plates. Historically, rigid window frames supported single glass lites holding them in place with neoprene or similar gasket material. This attachment method approximated simply supported edges that rotate about an axis parallel to the simply supported edges, deform in the plane of the glass lite, and do not deflect out-of-plane. Advances in structural silicone make it possible to produce rectangular single flat glass lites with edge fixity somewhere between that of simply supported edges and fully fixed edges. The authors applied the glass failure prediction model (GFPM) to a nonlinear finite-element model developed previously by the authors to determine the probability of breakage for selected single glass lite geometries with fully fixed edges under uniform lateral loads. The paper presents comparisons between results of analyses of lites with fixed edges with analyses of lites with simply supported edges. The comparisons indicate that not all single glass lite geometries benefit from fully fixing edges, but the benefits of doing so appear to increase as lite aspect ratio (AR) increases. The comparisons bracket benefits that can accrue from the partial fixity provided by structural silicone supports. The actual degree of fixity provided by structural silicone can only be determined experimentally, which lies outside the scope of this paper. [ABSTRACT FROM AUTHOR]

Composite steel bridges in the United Sates are typically constructed using 22 mm-diameter (7/8 in.-diameter) shear studs. The number of shear studs on a girder can be significantly reduced by using larger-diameter studs. This study employed 11 push-out tests to investigate the static performance of 29 mm-diameter (1-1/8 in.-diameter) shear studs. An extensive welding investigation was conducted to develop the optimum welding parameters for 29 mm-diameter studs. Results from experiments showed the static strength of 29 mm-diameter studs satisfied stud strength equations in the AASHTO LRFD Bridge Design Specifications and Eurocode 4. The ductility of the 29 mm studs was comparable or better than that of 22 mm-diameter shear studs. Concrete cracking under service level loading was similar between specimens with 22 and 29 mm studs. Observations indicate that the minimum allowable stud penetration into the concrete deck may need to increase in order for the 29 mm-diameter studs to have good static performance. Using partial-depth precast concrete panels in the bridge deck reduced the static strength of both 22 and 29 mm-diameter shear studs in push-out specimens. Efficient steel bridge girder design makes use of a composite action between the concrete deck and the steel girders. Composite action is achieved by welding shear studs to the top flange of the steel girder during fabrication or erection. The number of shear studs needed is directly related to the individual stud strength, which is controlled by the stud diameter. The shear stud diameter most commonly used in steel bridge construction throughout most of the United States is 22 mm. This paper presents laboratory experiments evaluating the static strength of 29 mm-diameter shear studs. The test results showed that 29 mm-diameter shear studs have a static strength that satisfies US bridge design standards. Compared with 22 mm-diameter shear studs, the use of 29 mm-diameter shear studs is estimated to reduce the number of studs needed on a steel bridge girder by 40%. This reduction in the number of shear studs can enhance construction safety, reduce the cost of fabrication, and facilitate the use of partial-depth precast concrete deck panels, which in turn can increase the speed of construction. [ABSTRACT FROM AUTHOR]

Wind energy is widely deployed and will likely grow in service of reducing the world's dependency on fossil fuels. The first generation of wind turbines are now coming to the end of their service lives, and there are limited options for the reuse or recycling of the composite materials they are made of. Current literature has verified that there is no existing recycling pathway (i.e., mechanical, chemical, thermal methods of recovery, etc.) for end-of-life materials in wind blades that can meet cost parity with landfilling in the US. However, to the authors' knowledge there is no study to date that uncovers the cost structures associated with repurposing wind turbine blades in the US. Repurposing could offer a cost-competitive advantage through displacement of higher-value products, rather than materials or chemical constituents alone. This study implements life cycle assessment (LCA) and life cycle cost analysis (LCC) to assess the environmental and financial implications at each stage of repurposing wind turbine blades as the primary load-carrying elements for high-voltage transmission line structures in the United States. This case study contribution to knowledge is based on the successful management of construction waste by analyzing an application for repurposing construction demolition waste. Specifically, this study presents an environmental and financial analysis of repurposing wind turbine blades as transmission line poles. Under this case study, our results show that BladePoles have lower greenhouse gas emissions than steel poles, and we anticipate BladePoles will be less costly than steel poles. Overall emissions are most sensitive to combustion emissions, driven primarily by transportation distance and hours of required crane operations during the installation process. Compared to other evaluated recycling methods, repurposing wind blades as BladePoles has the least overall global warming potential. As renewable energy production grows, managing infrastructure at its end-of-life is increasingly relevant—for example, wind turbine blades. This case study presents a financial and environmental analysis of repurposing decommissioned wind turbine blades as transmission poles, called BladePoles. This paper presents the cost and associated greenhouse gas emissions at each stage of the process. The case study also compares this reuse application to typical steel pole deployment, finding that for the same 60-year life span and 161 kV, 230 kV, and 345 kV transmission line poles, the BladePole cost is lower than the steel pole. Greenhouse gas emissions are most sensitive to transportation distance from the wind farm to the transmission project and the time of crane use for installation are key parameters in this case study and reducing them directly reduces the total greenhouse emissions overall. [ABSTRACT FROM AUTHOR]

Evidence-Based Design (EBD) principles are researched and published widely throughout the design, engineering, and construction industry. However, few studies show the extent of the implementation of the principles on actual projects. This paper documents the implementation of EBD elements relating to patient privacy and comfort in hospital renovation projects. The goal of Evidence-Based Design is to make design and construction decisions based on the best possible outcome for the user of a given space. In healthcare, this outcome may be critical to the health, comfort, privacy, and overall well-being of hospital patients and staff. This paper compiles the list of design recommendations relating to privacy and comfort. These recommendations come from a review of existing EBD literature. To assess the implementation of these elements into actual projects, construction documents from 30 recent healthcare facility renovation projects across the United States were obtained and analyzed. This paper provides results for the levels of implantation in the EBD categories of privacy and comfort. EBD elements related to privacy and comfort are shown to have a high level of adoption into actual projects. This may demonstrate the effectiveness of EBD in influencing design decisions. The report does show that there are still areas of potential improvement. Suggestions are given to improve building design, codes, standards, and guidelines. The information found in this study will be helpful to owners, building contractors, and design professionals by providing insight into how well the industry is recognizing and implementing the known best practices of EBD. These findings likewise introduce new opportunities for further research which could lead to additional improvements in healthcare facilities of the future. [ABSTRACT FROM AUTHOR]

Drought and population growth, especially in the western United States, are propelling a need for more efficient irrigation. Smart irrigation controllers, which interface with soil moisture, evapotranspiration (ET), or weather sensors, have been promoted as a demand-side management tool for this purpose. This paper reviews the body of research on residential smart irrigation controllers and their effectiveness. We find that smart irrigation controllers consistently reduce water demand by 15% among general users and more than 40% among indulgent users. Gaps in research include studies addressing peak demand reduction, centralized communication, data verifiability, and human factors of landscape management. Future work may develop techniques for coordinating networks of smart irrigation controllers to enable greater shifting and shaving of discretionary irrigation demands, similar to what is already happening in the electric grid, thereby creating an integrated water distribution system (IWDS). An IWDS may utilize smart irrigation controllers as direct load control devices at customer end points and interface with advanced metering infrastructure (AMI) and supervisory control and data acquisition (SCADA) systems at a central location to create more effective demand-side management (DSM) strategies for water conservation. Weather-based irrigation controllers (WBICs) have become the prevalent smart controllers used for residential irrigation scheduling. They are easy to install, have smartphone control, are easy to program, utilize local real-time weather data, prevent operating the irrigation system during rain or other adverse weather events, adjust watering schedules and duration seasonally, conserve water, and reduce water billing costs. In addition to the ease of use and benefits at the residential user level, smart irrigation controllers have the potential to provide the water utility with controls to buffer or shift peak irrigation demands. This buffering and shifting of peak demands have the potential to lower energy costs, decrease the carbon footprint, and delay costly infrastructure upgrades. With technological advancements and the proliferation of smart controllers, the future for water utilities will become more similar to the electrical grid industry. The smart controllers and technology will enable the development of the IWDS. The IWDS will allow the water utility to utilize data from AMI meters, SCADA systems, smart irrigation controllers, artificial intelligence, and other smart technology to operate more effectively and efficiently. [ABSTRACT FROM AUTHOR]

This paper delivers a detailed statistical assessment of pavement rehabilitation treatments by delivery methods via studying their performance in terms of pavement indicators (international roughness index, rutting depth, and pavement condition rating) and in terms of their pavement service lives. The data include 812 pavement segments that were rehabilitated under six commonly implemented treatments and through six commonly used delivery methods [with a focus on public–private partnerships (PPP)], which were let or completed in the United States between 1996 and 2011. The treatments include a two-course hot-mix asphalt (HMA) overlay with or without surface milling, concrete pavement restoration; three-course HMA overlay with or without surface milling; three-course HMA overlay with crack and seat of portland cement concrete pavement; 3R (resurfacing, restoration, and rehabilitation) and 4R (resurfacing, restoration, rehabilitation and reconstruction) overlay treatments; and 3R/4R pavement replacement treatments. The delivery methods/PPP types include performance-based contracting, cost-plus-time, incentives/disincentives, design-build and their derivatives, warranties, and lane rentals. To model and forecast pavement performance, a three-stage least-squares approach is employed. For the pavement service life analysis, the elapsed time until the pavement crosses a threshold is investigated, using random parameter hazard-based duration models. Separate models are estimated for each combination of delivery method/PPP type and rehabilitation type. The model estimation results show that several influential factors, such as traffic, weather, and pavement characteristics along with drainage condition affect pavement performance and pavement service life; these factors differ among pavement rehabilitation treatments and delivery methods/PPP types. [ABSTRACT FROM AUTHOR]

Using trip data from the SHRP-2 Naturalistic Driving Study (NDS) database collected at 12 sites in three states across the United States, this paper investigates driver behavior at freeway exit ramp terminals. First, the study qualitatively assesses driver speed behavior as they navigate the speed change lane (SCL) and the ramp. Starting at the beginning of the SCL and continuing after diverging onto the ramp controlling curve, a trend of continuous vehicle deceleration was evident, which continued throughout the SCL and ramp. It was also evident that a portion of drivers have a tendency to diverge onto the SCL on the taper and before the SCL has begun, where this behavior is dominant on the taper-type SCL. In general, statistical analysis revealed that the speed measures of driver behavior follow a normal distribution. The speed and deceleration measures at the study sites were statistically and significantly different, with the differences likely related to the geometric characteristics of each site. The data were then used to develop prediction models for the speed and deceleration measures. To account for the repeated measures induced by the same drivers in the dataset, linear-mixed models were developed for the speed and deceleration behavior measures. [ABSTRACT FROM AUTHOR]

As the United States' population grows and power delivery needs continue to expand, utility companies are presented with a unique opportunity to improve reliability, increase capacity, and provide innovations to power and pipeline production and delivery infrastructure. While there is research dedicated to the impacts of the regulatory environment on project performance and the profitability of power and pipeline projects, there has been no research dedicated to identifying the differences in planning processes for such projects. Therefore, this paper contributes to the construction body of knowledge by explicitly documenting how the regulatory environment impacts the planning metrics involved in power and pipeline utility projects. This paper explores how capital project planning varies for power and pipeline projects in both regulated and nonregulated environments through an analysis of 770 projects in the Independent Project Analysis (IPA), project database. This paper presents a statistical comparison of pipeline and power project planning indicators—front-end loading (FEL) score, budget spent on front-end planning, and stakeholders engaged in front-end planning—to understand the impact of the regulatory environment on project planning. The results suggest that for some planning indicators studied, regulated projects outperform nonregulated projects, and for other indicators, the reverse is true. In particular, results show that regulated pipeline projects have better a project definition at the time of project authorization than nonregulated pipeline projects based on the FEL score; the reverse is true for power projects. Regulated pipeline and power projects spend more in a budget on front-end planning than nonregulated pipeline and power projects. Lastly, key stakeholders are represented in both regulatory environments with little difference between nonregulated and regulated environments in both pipeline projects, but power projects in regulated environments engage the key stakeholders for more time. [ABSTRACT FROM AUTHOR]

Inspections are important to ensuring adequate safety and performance of a bridge throughout its service life. Bridge inspections are highly connected with maintenance decisions and can help in managing maintenance activities while maintaining a reliable bridge network. Routine inspections are the most common type of highway bridge inspections in the United States. The National Bridge Inspection Standards (NBIS) requires that, for almost all bridges, a routine inspection should be conducted at least every 24 months. However, limitations of current bridge inspection practices impact the quality of information provided about bridge conditions and the subsequent decisions made based on that information. Much research in the field of bridge inspection planning has been conducted to assist bridge inspectors in the inspection planning process and improving routine inspections. Accordingly, the goal of this study is to provide an overview on current bridge inspection practices in the United States and conduct a systematic literature review on innovations in the field bridge inspections planning while investigating research gaps and future needs. This paper provides a background on the history of bridge inspection in the United States, including current bridge inspection practices and their limitations and analyzes the connections between nondestructive evaluation techniques, deterioration models, and bridge inspection management. The primary emphasis of the paper is a thorough analysis of research proposing and investigating different methodologies for inspection planning and scheduling. Studies were analyzed and categorized into three main types of inspection planning approaches, based on: reliability, risk-analysis, and optimization approaches. The study revealed gaps and limitations in the current proposed techniques for inspection planning. The findings of this review will help in characterizing the current state of bridge inspection programs and future research needs to enhance inspection programs and reduce the gap between inspection practice and research. [ABSTRACT FROM AUTHOR]

Airports provide essential infrastructure to connect travelers and products to destinations across regions, nations, and the world. However, these connections were the focus of restrictions in the midst of a global pandemic because the same potential to provide access to people and products as a hub of long-distance travel can also serve as an opportunity to spread a virus. The objective of this paper is to explore the temporal effects of the COVID-19 pandemic on flight operations at airports in the US, in addition to an examination of the differences among various classifications of airports. For commercial service and general aviation airports, the airports with the quickest and most substantial recoveries were in areas with populations of under 100,000 people [within 48.2 km (30 mi) of the airport]. Airports with higher and lower populations within 48.2 km experienced sharper declines in flights and slower recoveries. Local, state, and national airport infrastructure investments will need to consider these effects and changes in demand spurred by COVID-19 while monitoring the long-term sustainability of the changes. [ABSTRACT FROM AUTHOR]

Hurricane-induced coastal floods pose a significant threat to near-shore communities for the United States and many other coastal areas around the world. Various mitigation measures have been developed to reduce infrastructure vulnerability. This paper proposes an engineering-based method to evaluate the influence of different flood mitigation strategies on residential structural vulnerability. The mitigation strategies studied are floor elevation, the elevation of utilities, wet floodproofing, and dry floodproofing. A probabilistic damage and cost analysis of building components is employed to modify existing fragility functions of unmitigated structures. The coastal flood fragility functions are then translated into vulnerability functions to express the mean damage ratio as a function of the hazard intensity, reflecting the influence of the mitigation measures. To evaluate the effectiveness of the strategy, the mitigated results are compared with the vulnerability functions of unmitigated residential structures. The proposed method is designed to incorporate independent calibration data from damage assessments readily and claims analyses and provides a useful tool to help decision-makers assess coastal flood mitigation measures on a quantitative basis. [ABSTRACT FROM AUTHOR]

This paper presents an iterative sandwich beam theory (ISBT) and a simplified version suitable for the design termed simplified sandwich beam theory (SSBT) used to predict the elastic mechanics of partially composite insulated concrete sandwich wall panels (SWPs) under flexural, axial, and thermal loads. These solution methods expand upon closed-form solutions to create a more general analysis technique. Design and analysis of SWPs are handled largely outside of codified documents and are almost exclusively designed such that they will remain within the elastic range. The presented ISBT and SSBT methods have been used in the United States precast industry since 2017 and are implemented in widely available software, LECWall, as of 2020, for predicting elastic deflections and stresses. In this paper, the ISBT and SSBT solution methods are validated with experimental data from the literature and using finite-element analysis. For the ISBT cracking moment and deflection, the measured-to-predicted ratio were 0.99 and 1.0 with coefficients of variation (COVs) of 0.10 and 0.11, respectively. For the SSBT cracking moment and deflection, the measured-to-predicted ratio was 0.99 and 0.99 with COVs of 0.21 and 0.19, respectively. For thermal loading, the ISBT and SSBT deflection m easured-to-predicted ratios were 0.95 and 0.90, respectively. The model was then used to investigate the behavior of sandwich wall panels under varying load combinations and with various section and material properties to demonstrate the robustness of the presented methods. [ABSTRACT FROM AUTHOR]

Dam failure can cause extraordinary flooding. Water and wastewater treatment plants, electricity generation facilities, bridges, highways, population centers, and other dams often lie downstream of a dam. If poorly maintained, aging dams can be overtopped by extreme rainfall events, and long-term loss of critical infrastructure services for many communities and regions may result. Such events are now more likely as the climate changes. How should we prioritize dams that need immediate attention and retrofit or remove them? Losses from a dam failure could exceed the infrastructure's replacement costs, through cascading effects in multiple sectors such as electricity, transportation, water supply, and environmental services. The existing dam hazard classification frameworks in the US and many other countries do not formally characterize "hazard hotspots" considering these impacts. Given that there are over 90,000 dams at different stages of repair, maintenance, and budgetary constraints, a systematic approach is needed to rank their potential failure hazard and allocate resources for risk mitigation. In this paper, we synthesize an approach for preliminary ranking of the priority areas of concern. The approach is scalable over many regions for rapid assessment of magnitude and exposure of a dam failure. The estimation of the consequences of a dam failure, including its financial losses, as well as affected critical infrastructures and population, is explored using publicly available dam break and consequence tools as well as national infrastructure data sets. [ABSTRACT FROM AUTHOR]

The Ogallala Aquifer, located in the Central Plains of the United States, is essential for agricultural irrigation and public water supply. Indiscriminate pumping from the aquifer has caused several negative impacts, such as deterioration of water quality and depletion of groundwater levels, which urgently demand better management. This paper applies hierarchical cluster analysis (HCA) and artificial neural networks (ANNs) for predicting annual groundwater levels in 403 wells of the Ogallala Aquifer. First, the methodology employed HCA to cluster homogeneous wells based on the time series of groundwater levels. Then, the study calibrated an ANN model for each cluster (composed of one or more wells) using previous annual values of groundwater levels as input. The HCA results showed a particular pattern in the spatial distribution of the 30 found clusters, revealing that the Ogallala Aquifer holds higher groundwater levels in the western part, which gradually decrease, advancing to the east. The ANN models provided proper predictions even for wells outside of the calibration data set. This investigation concludes that the integration of HCA and ANN enabled single models to accurately forecast annual groundwater levels for sets of wells in the Ogallala Aquifer. [ABSTRACT FROM AUTHOR]

Managed retreat in the form of voluntary flood-buyout programs provides homeowners with an alternative to repairing and rebuilding residences that have sustained severe flood damage. Buyout programs are most economically efficient when groups of neighboring properties are acquired because they can then create unfragmented flood control areas and reduce the cost of providing local services. However, buyout programs in the United States often fail to acquire such efficient, unfragmented spaces, for various reasons, including long administrative timelines, the way in which buyout offers are made, desires for community cohesion, and attachments to place. Buyout programs have relied primarily on posted price mechanisms involving offers that are accepted or rejected by homeowners with little or no negotiation. In this paper, we describe four alternative strategies that have been used successfully in land-preservation agricultural–environmental contexts to increase acceptance rates and decrease fragmentation: agglomeration bonuses, reverse auctions, target constraints, and hybrid approaches. We discuss challenges that may arise during their implementation in the buyout context—transaction costs, equity and distributional impacts, unintended consequences, and social pressure—and recommend further research into the efficiency and equity of applying these strategies to residential buyout programs with the explicit goal of promoting spatial coordination. [ABSTRACT FROM AUTHOR]

The decisions of whether and how to evacuate during a climate disaster are influenced by a wide range of factors, including emergency messaging, social influences, and sociodemographics. Further complexity is introduced when multiple hazards occur simultaneously, such as a flood evacuation taking place amid a viral pandemic that requires physical distancing. Such multihazard events can necessitate a nuanced navigation of competing decision-making strategies wherein a desire to follow peers is weighed against contagion risks. To better understand these trade-offs, we distributed an online survey during a COVID-19 pandemic surge in July 2020 to 600 individuals in three midwestern and three southern states in the United States with high risk of flooding. In this paper, we estimate a random parameter discrete choice model in both preference space and willingness-to-pay space. The results of our model show that the directionality and magnitude of the influence of peers' choices of whether and how to evacuate vary widely across respondents. Overall, the decision of whether to evacuate is positively impacted by peer behavior, while the decision of how to evacuate (i.e., ride-type selection) is negatively impacted by peer influence. Furthermore, an increase in flood threat level lessens the magnitude of peer impacts. In terms of the COVID-19 pandemic impacts, respondents who perceive it to be a major health risk are more reluctant to evacuate, but this effect is mitigated by increased flood threat level. These findings have important implications for the design of tailored emergency messaging strategies and the role of shared rides in multihazard evacuations. Specifically, emphasizing or deemphasizing the severity of each threat in a multihazard scenario may assist in: (1) encouraging a reprioritization of competing risk perceptions; and (2) magnifying or neutralizing the impacts of social influence, thereby (3) nudging evacuation decision-making toward a desired outcome. [ABSTRACT FROM AUTHOR]

In the United States, motor vehicle crashes are the leading reason of fatalities for young drivers in the age group of 16-19 years. This paper used naturalistic driving study (NDS) data to examine the safety of young drivers. The NDS data consist of comprehensive information related to driving behavior. The statistical modeling method (logistic regression) was used to investigate the relationship between factors of driver attention such as secondary tasks, impairments, hands on wheel, and crash risk to aid in the formulation of teen driving policy. The results indicated that nondriving tasks engagement such as cell phone use, external distraction, food and drink intake, personal hygiene, and reaching and handling objects in the vehicle increase the possibility of involvement in a safety critical event [odds ratio (OR) = 1.67-1.93]. Risk estimation for the observable impairments indicated that emotional state of the driver (OR = 6.01) and impairments (drugs/alcohol, OR = 5.02) exerted greater influence on crash likelihood compared to involvement in secondary tasks. The study revealed that not all secondary tasks pose the same risk. Transportation agencies can design behavioral countermeasures targeted at young drivers to help increase driver attention. Countermeasures such as increased enforcement, treatment and monitoring of the offender, and education and outreach programs for teenagers may help alleviate impaired driving. [ABSTRACT FROM AUTHOR]

This paper provides an observational before/after evaluation of the safety effects of edge-lane road (ELR) (also known as advisory bike lanes or advisory shoulders) installations in the United States. An ELR is a class of roadway that supports two-way automobile traffic within a single center lane and vulnerable road users (VRUs), i.e., bicyclists or pedestrians, in the edge lanes on either side. The use of a single lane by automobile users traveling in both directions is often a cause of potential safety concerns among the general public. This study employs a project-level empirical Bayes (EB) approach to before/after safety analysis for all US ELR sites where requisite crash data and other relevant characteristics were available. The analysis at 11 sites was performed with 8 years of crash data and more than approximately 60 million motor vehicle trips. Project-level EB analysis based on safety performance functions (SPFs) showed 8 of 11 ELR sites experienced a reduction in crash experience since installation. There was a ∼44% reduction in crashes among all sites compared to the expected crashes on the traditional two-lane two-way design that existed before ELR installation. This estimation assumed the calibration factor for all SPFs used in the EB analysis was 1.0. Because of the geographical spread of the ELRs being analyzed in this study, estimation of specific calibration factors for all 11 sites was beyond the scope of this work. To address this limitation, we conservatively assumed the SPF calibration factors to be 0.50 for locations for which calibration factors were not available. This assumption was made for 7 of the 11 sites. Even with this conservative assumption, the ELRs were estimated to have a ∼36% crash reduction. The results from this comprehensive evaluation of existing US ELRs should alleviate concerns the general public often has about the safety of ELRs for automobile users. [ABSTRACT FROM AUTHOR]

Water distribution network (WDN) leakage is estimated to account for more than 20% of potable water in the United States. Because existing leakage detection practices are mainly laborious or require excessive budget allocation, novel model-based techniques have become prevalent by employing smart meters. Specifically, incorporating machine learning and metaheuristic optimization methods into such model-based approaches to predict water pipeline leakage is one of the state-of-the-art approaches. This paper presents a predictive leakage detection approach by leveraging advanced metering infrastructure (AMI) and cyber-monitoring data. Primarily, the synchronous collection of consumption and monitoring data (i.e., flow and pressure) constitutes the proposed predictive tool in a combinative framework of genetic algorithms (GA) and particle swarm optimization (PSO). The time-consuming EPANET 2.2 simulation toolkit in MATLAB is circumvented by a set of trained artificial neural networks (ANNs). Sensitivity analyses are conducted to investigate the sensitivity of the proposed leakage prediction approach to multiple parameters. Ultimately, the number and location of the flow and pressure monitoring stations are optimized using maximum sensor availability thresholds. Mean absolute percentage error (MAPE) is employed to measure the model's accuracy. The proposed predictive tool offers insightful horizons on how considerable background leakage can be detected and prioritized without using labor-intensive, costly methods. [ABSTRACT FROM AUTHOR]

Land application of biosolids to improve the fertility of agricultural land is very common in the United States. Bioaerosols are airborne particulate matter (PM) aerosolized during various agricultural processes such as preapplication preparation, disking, application, and postapplication management. In recent years, there has been concern about the health of people living near the application sites even though these processes have been going on for decades. The focus of this study is to characterize PM inside households located near fields where biosolids have been applied. The PM was collected inside five houses on eight polytetrafluoroethylene (PTFE) filter papers using the GRIMM 1.108 dust monitor. Physical characteristics of PM were analyzed using the scanning electron microscope (SEM). The morphological properties of particles such as diameter, area, perimeter, aspect ratio, and shape factor of particles were determined using Image J software for the images captured using SEM. It was observed that there were a majority of particles in the range of 2.5–5 μm on all filter papers except two. The average PM2.5 over eight filters was observed to be about 32%, while for the ranges of 2.5–5.0 and 5.0–10.0 μm the averages was about 38 and 20%, respectively. The PM 2.5 averages for smoking, nonsmoking, control houses, and study houses were observed to be 40.63, 28.86, 33.37, and 31.28%, respectively. The shape-factor distribution and shape-distribution results indicate that there were a higher percentage of agglomerates, which was followed by spherical and pentagonal shaped particles. It was estimated that on an average 37.79% of PM collected over all the eight filters were agglomerates while 28.28% were spherical in shape. [ABSTRACT FROM AUTHOR]

In the event of contamination in a water distribution network (WDN), source identification (SI) methods that analyze sensor data can be used to identify the source location(s). Knowledge of the source location and characteristics are important to inform contamination control and cleanup operations. Various SI strategies that have been developed by researchers differ in their underlying assumptions and solution techniques. The following manuscript presents a systematic procedure for testing and evaluating SI methods. The performance of these SI methods is affected by various factors including the size of WDN model, measurement error, modeling error, time and number of contaminant injections, and time and number of measurements. This paper includes test cases that vary these factors and evaluates three SI methods on the basis of accuracy and specificity. The tests are used to review and compare these different SI methods, highlighting their strengths in handling various identification scenarios. These SI methods and a testing framework that includes the test cases and analysis tools presented in this paper have been integrated into EPA's Water Security Toolkit (WST), a suite of software tools to help researchers and others in the water industry evaluate and plan various response strategies in case of a contamination incident. Finally, a set of recommendations are made for users to consider when working with different categories of SI methods. [ABSTRACT FROM AUTHOR]

Several noteworthy stability failures occurred at landfills in the United States in the 1980s and early 1990s, a timeframe coinciding with the promulgation of modern US environmental regulations. These failures were extensively studied, and lessons were learned. A state-of-practice developed to enable the design of waste fills to be stable throughout their construction, operation, and closure periods. However, a survey of landfill performance in the United States in the 2010–2019 timeframe shows that waste fill stability failures continue to occur. This paper, an expansion of the 2018 Terzaghi Lecture given by the first author, presents a brief review of several waste fill failures from the 1980s and 1990s and the lessons learned during that period. Several more recent waste fill failures are then reviewed, from which it is concluded that 20–30 years after the earlier failures, facility operators and design engineers are relearning the earlier lessons, as well as new lessons related to evolving waste streams and operating practices. The paper concludes with a discussion of the current standard-of-care for the design of US waste fills and suggests that this standard can be improved through application of the lessons described herein. [ABSTRACT FROM AUTHOR]

A smart city plays an increasing role in citizens' daily life. A smart city has six main components, namely smart mobility, smart economy, smart governance, smart living, smart environment, and smart people. For the past several decades, government and organizations throughout the world have initiated many smart city projects. Citizens' transportation, education, investment, and other activities have been shifted from traditional to smart models through emerging technologies and the internet. In this paper, following the pioneering work of the intelligent quotient (IQ) test, we propose a framework to measure a city's intelligence level. We also propose a definition for the intelligence of an information system. To evaluate such intelligence, 382 technology indicators have been developed. We have applied smart city IQ testing on the top 100 largest cities in the United States (according to 2017 population). In addition, the smart city IQ score is designed so that it is convertible to the age of a human being. Various text mining and data mining methods (including classification) have been applied. The results of our analysis indicate that the average smart city IQ score is like that of an eight-year-old child. We also show the breakdown of IQ scores in terms of the six main components. Although the evaluation of the smart city projects in the United States is still ongoing, the results obtained so far as reported in this paper can provide important insights for research in this particular field, as well as intelligent information systems in general. [ABSTRACT FROM AUTHOR]

The concept of performance-based seismic design dates from the 1990s. Several complex bridges in seismic hazard zones were designed following this concept. The list includes but not limited to the New Carquinez Suspension Bridge, the New Tacoma Narrows Suspension Bridge, and the Gerald Desmond Bridge. This paper documents the fundamental issues that were considered in the seismic design of recent cable-supported bridges including the seismic performance-based criteria (PBDC). The paper also discusses how the local damage levels are employed through a deformation-based approach to achieve the global performance objectives of the bridge. The paper also explains the development procedure of spectrum compatible ground motions through probabilistic seismic hazard analysis. Issues such as foundation modeling, soil–structure interaction, and appropriate damping are also outlined. PBDC is an appropriate approach for the seismic assessment of this class of bridges, particularly if the damage is determined using a displacement-based assessment approach. [ABSTRACT FROM AUTHOR]

In a chloride-containing environment, steel bridges that use carbon steel can become corroded and require periodical inspection, repainting, and replacement to maintain an acceptable level of safety and serviceability during their service life. In recent years, several new bridges in the United States have adopted corrosion-resistant steels (i.e., ASTM A1010). Although corrosion-resistant steel can result in a substantial reduction in maintenance costs, its production cost is much higher than carbon steel. From a life-cycle cost perspective, the circumstances under which corrosion-resistant steel is economically advantageous remain unclear. The life-cycle costs that account for the uncertainties associated with traffic loads, including resistance, corrosion propagation, and maintenance activities further complicate this problem. The objective of this paper is to investigate the acceptance of corrosion-resistant steel in the design of steel girder bridges based on expected utility theory (EUT). The methodology developed will be exemplified on a steel girder bridge. Two types of utility functions will be used to characterize the preference of decision makers under uncertain conditions. The analysis results indicate that A1010 is the preferred solution for bridges in aggressive environments, or with severe failure consequences, or both, when the discount rate is low. [ABSTRACT FROM AUTHOR]

Several noteworthy stability failures occurred at landfills in the United States in the 1980s and early 1990s, a timeframe coinciding with the promulgation of modern US environmental regulations. These failures were extensively studied, and lessons were learned. A state-of-practice developed to enable the design of waste fills to be stable throughout their construction, operation, and closure periods. However, a survey of landfill performance in the United States in the 2010–2019 timeframe shows that waste fill stability failures continue to occur. This paper, an expansion of the 2018 Terzaghi Lecture given by the first author, presents a brief review of several waste fill failures from the 1980s and 1990s and the lessons learned during that period. Several more recent waste fill failures are then reviewed, from which it is concluded that 20–30 years after the earlier failures, facility operators and design engineers are relearning the earlier lessons, as well as new lessons related to evolving waste streams and operating practices. The paper concludes with a discussion of the current standard-of-care for the design of US waste fills and suggests that this standard can be improved through application of the lessons described herein. [ABSTRACT FROM AUTHOR]

With the boom of innovative technologies, information technologies in construction are getting enough attention, whereas construction technology implementation remains an undiscovered area. This paper explores the process of construction technology implementation, including the main activities, assessment criteria, and the mechanism through which it influences future technology purchase decisions. To achieve this purpose, 98 experienced practitioners from Australia and the United States were interviewed, and the process used by customers during technology adoption decisions was extracted in the form of thematic analysis. This paper presents an original framework including the key subprocesses of technology implementation describing the activities of customers and vendors, including operation commencement, maintenance set up, and assessment. In addition, the findings show that customers assess the implementation based on assessment criteria, including down time, interpersonal relationship, and technology operation quality. Comparison between the United States and Australia showed that rapport with the vendor is more important in large markets, whereas lead time and disposal are more important in remote markets. The findings contribute to the body of knowledge by validating a framework that incorporates both customer and vendor activities into a unique framework of three subprocesses. As for manufacturers, they can increase their competitive advantage by ensuring that their equipment has minimized downtime through swift provision of spare parts and maintenance information. [ABSTRACT FROM AUTHOR]

The increasing use of the Internet for many purposes is creating big data, many of which are generated from social media. These big data potentially could assist in obtaining valuable administrative information and even explore new social phenomena. Traditional ways of collecting data, such as questionnaire surveys, are time-consuming and costly. Therefore, the use of social media affords the opportunity to extract information that might be of benefit to the construction industry in a responsive and inexpensive manner. To this end, this paper explores whether information and knowledge that would be valuable in the construction domain can be generated by analyzing social media data. Twitter was selected for an initial trial analysis because of its wide usage in the United States. Because they represent a majority of the construction users in Twitter, the following four user clusters were selected and analyzed: construction workers, construction companies, construction unions, and construction media. For each user identified in the four clusters, the 3,200 most recent Twitter messages were collected, which were analyzed from the following aspects: sentiment analysis, topic modeling, link analysis, geolocation analysis, and timeline analysis. Different data-analysis methods were used for the specific themes, such as Stanford Natural Language Processing (StanfordNLP) for sentiment analysis. The detailed findings, benefits, and barriers to incorporating social media data analytics in the construction industry, as well as future research directions, are discussed in this paper. For example, the sentiment analysis results indicated that construction workers tend to have a higher proportion of negative messages compared to the other clusters, which may prompt more attention to emotional guidance and understanding by construction companies and the public. This paper benefits academia by testing an alternative way of studying the construction population, which could help decision makers gain a better understanding of real-world situations in the construction industry. [ABSTRACT FROM AUTHOR]

The focus of this paper is on evaluating the safety effectiveness of converting a stop-controlled intersection with a speed limit ≥ 56.3 km=h (35 mi=h) to a miniroundabout and examining the role of influencing factors on their safety effectiveness in the United States. Crash, traffic volume, and geometry data for 25 miniroundabouts in eight states was collected to conduct before-after analysis using the empirical Bayes (EB) method. In addition, crash and traffic volume data for 723 reference intersections were gathered and used for computing the calibration factors and developing jurisdiction-specific safety performance functions (SPFs). A 19.63% and 60.55% reduction in the number of total crashes and fatal and injury (FI) crashes but an 7.72% increase in property damage only (PDO) crashes was observed when a two-way/one-way stop-controlled (TWSC/OWSC) intersection was converted to a miniroundabout. A 224.76%, 74.30%, and 282.71% increase in the number of total crashes, FI crashes, and PDO crashes was observed when an all-way stop-controlled (AWSC) intersection was converted to a miniroundabout. Converting a TWSC/OWSC intersection to a miniroundabout has better safety benefits than converting an AWSC intersection to a miniroundabout. The recommended crash modification factors (CMFs) for converting a TWSC/OWSC intersection to a miniroundabout are 0.80, 0.39, and 1.08 for total, FI, and PDO crashes. The recommended CMFs for converting an AWSC intersection to a miniroundabout are 3.25, 1.74, and 3.83 for total, FI, and PDO crashes. The number of crashes in the before period, cross-street traffic volume, speed limit at major street and cross-street, and intersection skewness have a statistically significant influence on the safety effectiveness of miniroundabouts at a 90% confidence level. These findings are useful to researchers and practitioners for conducting safety benefit analysis and making informed decisions pertaining to converting a stop-controlled intersection to a miniroundabout. [ABSTRACT FROM AUTHOR]

As public utility owners face increased budget constraints and greater expectations, alternative project delivery methods will increasingly be used to fast track projects, reduce costs, promote innovation, and ensure proper performance for water and wastewater facilities. The goals of public utility owners and U.S. federal tax regulations suggest why design-build-operate (DBO) projects have been selected over other procurement processes. The research reported in this paper contributes to the body of knowledge and benefits industry practitioners, by identifying tax regulations and best practices that when jointly considered improve the project delivery selection process, while enhancing risk-mitigation efforts on DBO water and wastewater projects. A procurement selection process using multiple-criteria decision and financial risk analyses is presented to select the most economically sustainable delivery method given each project's characteristics. A present value analysis establishes a range of values that takes into account variables that will potentially impact lifecycle costs. The selection of the procurement process and the contractor is based on best value where financial risks to the concerned government and contractor are mitigated through dynamic service fee agreements in accordance with current U.S. federal tax regulations. [ABSTRACT FROM AUTHOR]

In highway design, inverted-T bridge caps (ITBCs) have been extensively used in the United States. Depending on the project requirements, some ITBCs need to be skewed. In Texas, the traditional method of flaring the transverse reinforcement out is used to design the skewed ITBCs, as stated in the Texas Department of Transportation (TxDOT) Bridge Design Manual. However, this method has significant drawbacks in terms of design and construction. To solve the complexities of the traditional method, the skewed reinforcing method is proposed to TxDOT. In this paper, to enlarge the knowledge of the structural behavior and the economic impact of skew reinforcing in ITBCs, the nonlinear finite-element (FE) simulation and cost–benefit analysis of 96 full-scale skewed ITBC models are performed. The structural and economic performance of the specimens are investigated and compared according to the following design variables: (1) skew angle; (2) transverse reinforcement detailing; (3) amount of the transverse reinforcement; (4) presence of the end reinforcement; (5) size of the diagonal end reinforcement; and (6) the concrete strength. The finite-element analysis shows that skew reinforcing can achieve better structural performance than the traditional method in terms of stiffness, crack width, and the ultimate capacity. Moreover, the skew transverse reinforcement method considerably reduces the design and construction costs. [ABSTRACT FROM AUTHOR]

Over the last few decades, wildfires in the United States have caused severe damage and property losses. As more houses are being built in areas prone to wildfire, enhancing the fire resistance of structures and buildings is critical and in great need. This paper presents a preliminary study to explore and develop some innovative surface-bonded fire-resistant coating materials for this purpose. The feasibility of these materials [i.e., high performance cement mortar (HPCM), geopolymer mortar (GPM), and magnesium phosphate cement mortar (MPCM)] was assessed considering the workability, adhesion to structure surface, and fire property. The Taguchi-based mix designs of HPCM, GPM, and MPCM were first evaluated and optimized by using Minitab Response Optimizer. The MATLAB image analysis was used to evaluate the slip resistance of the three optimum mix designs. The cohesiveness, adhesiveness, and fire resistance of the three coating materials were analyzed and compared. The spray area expansion ratio of MPCM was approximately 1.7 times of HPCM and GPM, indicating that HPCM and GPM had better slip resistance than MPCM. The HPCM had the best cohesiveness and adhesiveness with its buildup thickness 0.5 and 1.0 mm higher, and its rebound about 5% and 10% lower than GPM and MPCM, respectively. The fire-resistance test including observation of color change and cracking indicated that MPCM could withstand temperatures as high as 1,000°C, and MPCM had better fire resistance than HPCM and GPM. [ABSTRACT FROM AUTHOR]

This paper documents the in-place recycling of a high-traffic project (12,000 vehicles per day) on U.S. highway 49 (US-49). Sections built included asphalt emulsion–stabilized cold in-place recycling (CIR), portland cement–stabilized CIR, cement-stabilized fulldepth reclamation (FDR), and traditional construction. This paper’s objective is to present a case study of US-49 construction and performance through approximately 4.5 years of service. Performance was characterized by a distress survey, cored properties, and falling weight deflectometer testing. In particular, findings demonstrated performance and economic trade-offs between cement CIR and emulsion CIR, which could be directly applied to planning decisions. Emulsion CIR exhibited sufficient rutting capacity but reserve cracking capacity, at higher costs relative to cement CIR. Cement CIR, however, was more economical and exhibited excess rutting capacity but not excess cracking capacity. Because there is little need for reserve capacity of one distress when other distresses are past capacity, this paper proposes balanced binder blends (examples might include 2.5% emulsion with 2% cement, or 3% emulsion with 1.5% cement) for future consideration because they can provide sufficient capacity for multiple distresses while balancing economics. [ABSTRACT FROM AUTHOR]

Sediment accumulation in reservoirs across the world diminishes reservoir benefits, increases maintenance costs, and damages the environment. United States regulatory policy requires State and Federal permits for discharging sediment into waterways, which has tended to discourage alternatives that pass sediment downstream of the dam. The cost of methods that remove the sediment from the fluvial system is usually prohibitive and is a major factor precluding sustainable sediment management in the United States and other countries with similar sediment reduction policies. This paper challenges the notion that US policy requires sediment removal and terrestrial storage by highlighting seven case studies in the United States where reservoir sediment management included downstream sediment discharge. Where technically feasible, these types of solutions can lead to greater economic and environmental sustainability of US reservoirs. [ABSTRACT FROM AUTHOR]

The right-turn flashing yellow arrow (FYA) signal display is still considered a new signal practice in the United States. The Manual on Uniform Traffic Control Devices (MUTCD; 2009) allocates a signal phasing section for the right-turn FYA, which requires a four-section configuration. It supports multiple phase indications that guide the motorists through permissive, protected, or permissive or protected phases. However, there are no right-turn FYA or protected permissive right turn (PPRT) guidelines in place with a focus on operational efficiency. In this paper, we investigated two permissive right-turn FYA phases in various traffic conditions and signal timing plans. The first permissive right-turn FYA phase is the right turn on impeding through (RTOIT) taking place during cross-street through movement. The second permissive right-turn FYA phase occurs during opposing left-turn movement and is thus called right turn on impeding left (RTOIL). We aimed to develop warrants leading to the efficient implementation of permissive right-turn FYA phases based on a microsimulation analysis. The response, the average maximum right-turn throughput (MRTT) per cycle, was categorized into three categorical variables represented as the nonefficient (NE), low efficient (LE), and efficient (E) categories depending on the number of executed right turns per cycle. A multinomial logit model was developed to establish a decision support system that predicts the efficiency attributes of the permissive RTOIT and RTOIL FYA phases that can help traffic management center operators in planning and operational-level applications. [ABSTRACT FROM AUTHOR]

Investments and policies for transportation infrastructure projects are influenced and possibly undermined by diverse stakeholders with limited incentive for coordination. Effective management of such systems requires agencies to prioritize capacity projects with consideration of potential stakeholder-divergence resulting from competing stakeholder values and budgetary constraints. Strategic prioritization of investment should consider the values of several stakeholder perspectives, such as managing agencies, the public, closely associated commerce, environmental agencies, and others. This paper will demonstrate an integrated scenario analysis, multicriteria analysis, and integer-programming approach to identify investment portfolios that meet budgetary constraints while promoting investments most suitable for coordination among diverse stakeholders. The approach will be demonstrated on six high-priority federal transportation infrastructure projects in the United States. The results illustrate the need and use of stakeholder-divergence as a factor in federal investment policies. The methods result in proactive identification of dissent or progressive issues early in the project planning process, potentially avoiding postimplementation regret. [ABSTRACT FROM AUTHOR]

Dams are continuing to age and deteriorate that affect the service life of the dams in the U.S. Risk assessment is required to understand the behavior of dams and to prioritize the remedial actions and maintenance, and yet it is quite challenging to do risk assessment since it requires extensive current and historical data from in situ instrumentation on dams and detailed design, construction, and operation information. Currently, the required data for risk assessment resides in various paper-based and digital documents that hinder the capabilities of risk assessors to gather, analyze, and visualize the data flexibly from various engineering perspectives such as geotechnical, hydrologic, geologic, and structural. As a result, getting a holistic view of a dam's current condition and its behavior over time becomes a time and resource intensive task. There is a need for an integrated shared knowledge repository for dams to streamline the risk assessment process. The research described in this paper provides requirements for developing such a shared knowledge repository for risk assessment of embankment dams that would support the information needs of various engineering domains and the means and methods for integrated assessment, visualization, and data analytics to understand the risk of internal erosion. [ABSTRACT FROM AUTHOR]

Engineering practitioners have widely adopted probabilistic methods for estimating liquefaction triggering hazards. Unfortunately, incorrect application of these methods has become commonly accepted in the United States and throughout many parts of the world. In this paper, we describe two specific incorrect applications of probabilistic liquefaction triggering prediction models that are commonly used in engineering practice: (1) improper parametric uncertainty characterization when using the models, and (2) the application of a conservative factor of safety thresholds to deterministic cyclic resistance ratio boundaries. These two practices and their implications are discussed, and illustrative examples and figures are presented. We also discuss the apparent inconsistencies in what constitutes an acceptable risk for liquefaction hazards and other significant geotechnical hazards, such as slope stability. We demonstrate the need to collectively consider the likelihoods of all aspects of liquefaction hazard problems—susceptibility, initiation, and effects—when calculating and considering liquefaction risk. Finally, we point to the concept and framework of performance-based earthquake engineering as a logical and objective path forward for dealing with the challenges raised in this study. [ABSTRACT FROM AUTHOR]

Dynamic occupant action amplifies demands on structures compared to static loads and is often neglected in design. This paper focuses on 15 light-frame floor collapses caused by dynamic amplification of occupant loads, specifically rhythmic movements of jumping, dancing, and bouncing. This study investigates the increase in floor collapse cases due to occupant loadings near college campuses, their implications, and makes recommendations to reduce future collapse risk. Of the 15 cases studied herein, most failures occurred in multifamily structures within 1.6 km (1 mi) of a university in the East United States. All were determined by investigators and local building or city officials to be a result of dynamic occupancy overloads. Nine of the 15 (60%) overloaded floors were framed using metal-plate connected wood trusses. It is recommended that engineers elect to design multifamily structures in close proximity to universities above code live load minimums to counteract probable dynamic overload from gatherings. [ABSTRACT FROM AUTHOR]

The United States Army is constructing a new water-treatment facility for Fort Irwin/National Training Center in the Mojave Desert region of southern California to address existing regulatory requirements and to account for anticipated expansion at the installation. The proposed treatment, electrodialysis reversal (EDR), is anticipated to recover 92% of the influent water. The ultimate goal was to achieve 99% recovery, which required additional recovery of the EDR concentrate. This paper describes laboratory testing of conventional watertreatment methods to achieve water recovery beyond standard practice. The effectiveness of lime softening followed by secondary reverse osmosis (RO) was evaluated to treat the concentrate stream and recover additional water to approach 98%. Partial lime softening at dosages of 500 - 2,000 mg/L of hydrated lime was capable of removing hardness from simulated EDR concentrate. Adding magnesium chloride to the lime softening step increased silica removal, bringing SiO2 concentrations in the simulated EDR concentrate from 110 to 6.8 mg/L at room temperature. The resulting treated water was suitable for effective reverse osmosis with a standard seawater polyamide membrane. Rejection for all of the dissolved constituents was well above 90% with the exception of arsenic, which was reduced from 50 μg/L to levels on the order of 20 μg/L. To achieve 99% recovery, mechanical vapor recompression is being considered to further recover the concentrate from the RO unit, although this unit process was not evaluated in the research reported in this paper. [ABSTRACT FROM AUTHOR]

This paper presents results from a qualitative analysis study conducted on the integration of structure in a building. If integration is to become more of a priority, what does this mean to structural engineers, and how do they add value? Eighty-five total participants--38 architects, 46 structural engineers, and one practicing as both--were interviewed in four major U.S. cities to record their experiences. The practitioners identified structural integration as being multifaceted, and the scope of structural integration is bigger and broader than what has been presented previously. Due to the need to understand the perspectives for each of the fields individually and the large number of responses, the analysis presented here encapsulates the responses from only the structural engineering professionals. Engineering practitioners incorporate aspects of time, professional relationships, and a collaborative environment with structural integration. Integration also includes working toward goals such as technical innovation, constructability, architectural design, combining structures with other systems, and ensuring that the owner's needs are met. Both the process and the aims lead to the physical articulation of the structure through its expression, detailing, and construction. A proposed framework for structural integration has been constructed from the responses to expand the current definition. With the changing practice environment, structural engineers need to consider what integrated design means to their profession, and this paper is intended to aid this process. [ABSTRACT FROM AUTHOR]

The Complete Streets movement has been steadily gaining attention in the United States over the last 16 years. Adoption of policies that encourage street designers to consider the needs of all users—and not only automobile users—have become more widespread, with over 1,400 US jurisdictions formally embracing Complete Streets policies. The promised benefits of Complete Streets policies are far reaching, but rigorous studies proving these benefits are rare. This paper reviews the state of the practice of Complete Streets and some attempts to catalogue the outputs and outcomes of Complete Streets projects, and analyzes case studies to determine best practices. [ABSTRACT FROM AUTHOR]

Partnering has enabled state departments of transportation (DOTs) and aviation construction projects to significantly reduce claims and improve project schedules. Today there is a wide body of empirical evidence that demonstrates partnering benefits outweigh the resources devoted to its implementation. Despite such outstanding outcomes, collaborative partnering is still new, misunderstood, underutilized, and evolving for airport construction projects that entail greater complexity and increased risks due to a high number of stakeholders and additional sector-specific regulations. The objectives of this study are to describe the state-of-practice regarding partnering in the aviation construction industry and offer insights about its use. A comprehensive survey of industry professionals representing DOTs, airports, and others involved in construction aviation projects in the United States helps capture partnering trends across the industry. Findings show that participants with experience in partnered-aviation construction projects perceive higher improvement of safety and reduced claims offering greater rewards. However, these projects are operating as late adopters of partnering with many at the initial stages of implementation. The main contribution of the paper to the body of knowledge is that partnering is suitable for airport projects regardless of the project delivery method followed, budget size, or partnering intensity levels. Those with greater experience with partnering under design-bid-build project delivery methods are more likely to perceive higher improvements. Furthermore, it increases trust and strengthens the relationships between organizations. The findings are significant as they bring attention to team integration practices for improved outcomes via the underutilized partnering in an industry niche where stakeholder and risk management are key to project success. [ABSTRACT FROM AUTHOR]