Showing papers in "Journal of Infrastructure Systems in 2014"

Resilience and Sustainability of Civil Infrastructure: Toward a Unified Approach

Abstract: In recent years, the concepts of resilience and sustainability have become very topical and popular. The concept of sustainability rose to prominence in the late 1980s and became a central issue in world politics, when the construction industry began to generate the first sustainable building assessment systems with more or less equally weighted environmental, economic, and social aspects for office buildings over their life cycles. On the other hand, resilience is usually connected to the occurrence of extreme events during the life cycle of structures and infrastructures. In the last decade, it has been used to minimize specifically direct and indirect losses from hazards through enhanced resistance and robustness to extreme events, as well as more effective recovery strategies. A detailed comparison of the studies dealing with either infrastructure sustainability or resilience presented in this paper leads to the conclusion that they have a vast number of similarities and common characteristics. For instance, they both combine structural analyses with social and economic aspects; they both rely on techniques for the life-cycle analysis and decision making; they both are in an early stage, where the academic world is trying to find the best way to promote the application of the scientific results among professional engineers and the industry. Indeed, both approaches try to optimize a system, such as a civil infrastructure system, with respect to structural design, utilized material, maintenance plans, management strategies, and impacts on the society. However, for the most part, researchers and practitioners focusing on either resilience or sustainability operate without a mutual consideration of the findings, which leads to a severe inefficiency. Therefore, this paper suggests that resilience and sustainability are complementary and should be used in an integrated perspective. In particular, the proposed approach is rooted in the well-established framework of risk assessment. The impact of the infrastructure and its service states on the society in normal operational conditions (assessed by sustainability analysis) and after exceptional events (assessed by resilience analysis) should be weighted by the associated probabilities of occurrence and combined in a global impact assessment. The proposed perspective and assessment technique is applicable to various types of civil infrastructure systems, but the case of transportation networks and bridge systems is emphasized herein. A numerical application dealing with the comparative analysis of two possible bridge layouts is presented to exemplify the approach. The results show that both resilience and sustainability analyses assess a relevant amount of the impact of the bridge on the community where it is built, so neither one can be neglected.

Comparative Life Cycle Assessment of Conventional, Glass Powder, and Alkali-Activated Slag Concrete and Mortar

Abstract: This study compares the cradle-to-gate greenhouse gas emissions (GHGs), energy use, water use, and potential environmental toxicity of conventional (Conv), glass powder (GP), and alkali-activated slag (AAS) concrete and mortar. The comparison is based on 1 m3 of concrete/mortar with similar 28-day compressive strength, so the same concrete/mortar member with same dimensions may be manufactured from Conv, GP, or AAS materials and used for same applications. The result shows that compared to a 35-MPa Conv concrete, a 35-MPa GP concrete has, on average, 19% lower GHGs, 17% less energy, 14% less water, and 14–21% lower environmental toxicity. A 35-MPa AAS concrete has 73% lower GHGs, 43% less energy, 25% less water, and 22–94% lower effects for all environmental toxicity categories except an 72% higher ecotoxicity effect. Environmental impact reductions are also found for using GP as a cement replacement in concrete with lower strengths and replacing cement with GP or AAS in mortars with different st...

Estimating the Consumptive Use Costs of Shale Natural Gas Extraction on Pennsylvania Roadways

Abstract: The development of natural gas resources in the Marcellus Shale formation has progressed rapidly in the last several years, particularly in the Commonwealth of Pennsylvania. These activities require many heavy truck trips for equipment and materials, which can damage state and local roads that were not designed for high volumes of heavy truck traffic. For state transportation agencies, one measure of costs of shale gas development is the potential degradation of roadways resulting from shale gas development. This technical note, provides a first-order an estimate of roadway consumptive use costs of additional heavy truck traffic on Pennsylvania state-maintained roadways from Marcellus Shale natural gas development in 201, estimated at 1 about $13,000–$23,000 per well for all state roadway types, or $5,000–$10,000 per well if state roads with the lowest traffic volumes are excluded. This initial estimate of costs, is based on data on the distribution of well activity and roadway type in Pennsylvani...

Impact of Road Conditions and Disruption Uncertainties on Network Vulnerability

Abstract: Researchers have studied the vulnerability of roadway systems to disasters, such as terrorist attacks or natural disasters. However, the literature has not explicitly addressed other factors, such as infrastructure condition, that can significantly affect the vulnerability of roadway systems. In this study, the authors developed an algorithmic framework to address how the condition of a roadway network affects its vulnerability to disruptions. The vulnerability of the network was computed with respect to two measures: network efficiency and vehicle miles of travel. The results show that the average condition of the roadways in the network, the difference between the conditions of the roads, the uncertainties associated with road disruption probabilities, and link topological positions affect the roadway vulnerability.

Simultaneous Network Optimization Approach for Pavement Management Systems

Abstract: In the context of sequential decision making under uncertainty, the Markov decision process (MDP) is a widely used mathematical framework. The MDP-based approaches in the infrastructure management literature can be broadly categorized as either top-down or bottom-up. The former, while efficient in incorporating system-level budget constraints, provide randomized policies, which must be mapped to individual facilities using additional subroutines. Conversely, although state-of-the-art bottom-up approaches provide facility-specific decisions, the disjointed nature of their problem formulation does not account for budget constraints in the future years. In this paper, a simultaneous network-level optimization framework is proposed, which seeks to bridge the gap between the top-down and bottom-up MDP-based approaches in infrastructure management. The salient feature of the approach is that it provides facility-specific policies for the current year of decision making while utilizing the randomized pol...

Fuzzy-Based Model for Predicting Failure of Oil Pipelines

Abstract: Oil and gas pipelines transport millions of dollars of goods worldwide every day. Even though they are the safest way to transport petroleum products, pipelines do still sometimes fail, generating hazardous and irreparable environmental damages. Many models have been developed in the last decade to predict pipeline failures and conditions. However, most of these models were limited to one failure type, such as corrosion failure, or relied mainly on expert opinions. The objective of this paper is to develop a fuzzy-based model to predict the failure type of oil pipelines using historical data of pipeline accidents. The model was able to satisfactorily predict pipeline failures due to mechanical, operational, corrosion, third-party, and natural hazards with an average percent validity of 83%. This research contributes to the body of knowledge by developing a robust failure type prediction model for oil pipelines using a fuzzy approach. The model will assist pipeline operators to predict the expected...

Connected Vehicle Approach for Pavement Roughness Evaluation

Abstract: Connected vehicles present an opportunity to monitor pavement condition continuously by analyzing data from vehicle-integrated position sensors and accelerometers. The current practice of characterizing and reporting ride quality is to compute the international roughness index (IRI) from elevation profile or bumpiness measurements. However, the IRI is defined only for a reference speed of 80 km/h. Furthermore, the relatively high cost for calibrated instruments and specialized expertise needed to produce the IRI limit its potential for widespread use in a connected vehicle environment. This research introduces the road impact factor (RIF), which is derived from vehicle integrated accelerometer data. The analysis demonstrates that RIF and IRI are directly proportional. Simultaneous data collection with a laser-based inertial profiler validates this relationship. A linear combination of the RIF from different speed bands produces a time-wavelength-intensity-transform (TWIT) that, unlike the IRI, is...

Efficient Algorithm for Crack Detection in Sewer Images from Closed-Circuit Television Inspections

Abstract: This paper presents a new algorithm for automated crack detection in sewer inspection closed-circuit television (CCTV) images Cracks often have a long and thin rectangular shape with a dar

Life Cycle Asset Management Methodologies for Buildings

Abstract: Although asset management methodologies and tools related to the civil infrastructure domain have existed for decades, there are many challenges in applying these same techniques to buildings. This is because of the complexity and diversity of building structures, and their ownership profile. Numerous influences including scarcity of energy and material resources and land are creating greater awareness of the need for structured building management to reduce total life cycle needs. This reduction in consumption needs to be balanced with the requirements of the building occupant, such that building services are provided at a certain level of quality over a specified lifespan. Whether the building reaches that life and how it performs in service depends on maintenance, repair, and modernization during that timeframe, or restoration and recapitalization near the end of that timeframe. Optimal facility asset management needs to consider minimizing the life cycle costs related to these activities, whil...

Assessing the Long-Term Performance of Cross-Sectoral Strategies for National Infrastructure

Abstract: National infrastructure systems (energy, transport, digital communications, water, and waste) provide essential services to society. Although for the most part these systems developed in a piecemeal way, they are now an integrated and highly interdependent “system of systems.” However, understanding the long-term performance trajectory of national infrastructure has proved to be very difficult because of the complexity of these systems (in physical and institutional terms) and because there is little tradition of thinking cross-sectorally about infrastructure system performance. Here, a methodology is proposed for analyzing national multisectoral infrastructure systems performance in the context of uncertain futures, incorporating interdependencies in demand across sectors. Three contrasting strategies are considered for infrastructure provision (capacity intensive, capacity constrained, and decentralized) and multiattribute performance metrics are analyzed in the context of low, medium, and high demographic and economic growth scenarios. The approach is illustrated using Great Britain and provides the basis for the development and testing of long-term strategies for national infrastructure provision. It is especially applicable to mature industrial economics with a large stock of existing infrastructure and challenges of future infrastructure provision.

Life-Cycle Management of Fatigue-Sensitive Structures Integrating Inspection Information

Abstract: Successful management of deteriorating structures requires the reliable prediction of damage occurrence as well as the time-dependent damage propagation under uncertainty. The reliability of the performance prediction process can be significantly improved by integrating information gained from inspection and monitoring actions. This integration leads to a more accurate prediction of the time-dependent damage level and, eventually, to a better supported decision-making process. In this paper, a probabilistic approach is proposed to find an optimum management plan for fatigue-sensitive structures by integrating the available information from inspection actions. The proposed approach utilizes a probabilistic time-dependent damage criterion, inspection cost, and failure cost to find the optimum inspection times under uncertainty. New information resulting from inspection actions performed during the lifetime of the structure is used to update the damage propagation parameters as well as the optimization procedure. This process results in an enhanced management plan which can provide managers the ability to make real-time decisions based on inspection results. The integration of this new information and its impact on the life-cycle management process are thoroughly investigated. In addition, a realistic fatigue critical detail is used to illustrate the proposed probabilistic approach.

Fuzzy Multicriteria Decision-Making Approach for Pavement Project Evaluation Using Life-Cycle Cost/Performance Analysis

Abstract: Project life-cycle cost analysis (LCCA) is a reasonable approach to compare pavement design alternatives, but not taking into consideration of pavement performance in the most LCCA approaches may lead not to obtain the most desirable alternative for road users and associated highway agencies. This article introduces a multicriteria decision making method for pavement project evaluation using LCCA that (1) utilizes fuzzy set theory to model and handle uncertainties; (2) takes into account the extra user costs attributable to inadequate pavement condition; and (3) as a criterion, considers life-cycle pavement performance that describes overall pavement serviceability condition. Using a hypothetical project, the paper clarifies the performance of the proposed method for long-term evaluating alternative pavement design strategies. The alternatives are compared with respect to each criterion of the method, and also using sensitivity analysis, it is determined that changes in the decision maker’s risk and confidence attitudes can affect the ranking of the alternatives.

Importance of Sustainability-Related Cost Components in Highway Infrastructure: Perspective of Stakeholders in Australia

Abstract: Highway infrastructure development typically requires major capital input. Unless planned properly, such requirements can cause serious financial constraints for investors. The push for sustainability adds a new dimension to the complexity of evaluating highway projects. Finding environmentally and socially responsible solutions for highway construction will improve its potential for acceptance by the society and in many instances the infrastructure’s life span. Even so, the prediction and determination of a project’s long-term financial viability can be a precarious exercise. Existing studies in this area have not indicated details of how to identify and deal with costs incurred in pursuing sustainability measures in highway infrastructure. This paper provides insights into the major challenges of implementing sustainability in highway project development in terms of financial concerns and obligations. It discusses the results from recent research through a literature study and a questionnaire survey of key industry stakeholders involved in highway infrastructure development. The research identified critical cost components relating to sustainability measures based on perspectives of industry stakeholders. All stakeholders believe sustainability related costs are an integral part of the decision making. However, the importance rating of these costs is relative to each stakeholder’s core business objectives. This will influence the way these cost components are dealt with during the evaluation of highway investment alternatives and financial implications. This research encourages positive thinking among the highway infrastructure practitioners about sustainability. It calls for the construction industry to maximize sustainability deliverables while ensuring financial viability over the life cycle of highway infrastructure projects.

Restoration and Impacts from the September 8, 2011, San Diego Power Outage

Abstract: This case study discusses post-event reconnaissance research of the September 8, 2011, power outage that left San Diego County, California, without electricity for up to 12 h. The objective of this case study is to synthesize and analyze the impacts of the outage and responses to the event. Understanding the outage’s impacts and responses helps to reveal restoration practices and contexts that promote meeting both technical and nontechnical goals. This study reveals several issues related to restoration decision-making and communication related to critical customers, particularly those responsible for health care, wastewater and potable water management, fuel provision, and food service. Restoration did not occur and was not communicated in such a way to avoid impacts to dependent critical infrastructure, reflect state restoration criteria, or meet expectations of a variety of power customers. Insight from this case study suggests three themes to guide research and development of best practices fo...

A Dynamic Vehicle-Track Interaction Model for Predicting the Track Degradation Process

Abstract: Due to the repeated passage of trains, differential settlements are observed in the vertical direction of the railway tracks. These settlements depend on the platform quality, on the train speed, on the dynamic load, and on the track structural behavior. In recent years, several authors have defined laws and models for the prediction of settlement. The majority of those settlement models only consider the vertical degradation of the track, disregarding this phenomena in the lateral direction, since the vertical track geometry deteriorates faster than the horizontal one. In these models also the dynamic nature of the vehicle load is not considered accordingly. This paper presents a vehicle-track dynamic-interaction model for predicting the evolution of the vertical track profile and assessing the track response along the degradation process. The model is one-dimensional (1D) and it estimates the track degradation from a settlement law that uses deformation under instantaneous wheel passage as input. Although track degradation is a three-dimensional (3D) process, a 1D model is considered because the vertical component of the track settlement is the largest one. In order to predict the evolution of the track settlement due to the passage of the dynamic loads on the track, an iterative procedure is proposed. One cycle of this methodology is composed by three phases: numerical calculation of the train-track dynamic-interaction loads along the track, calculation of the track settlement, and definition of the track profile after settlement. Then, a new cycle begins. The proposed methodology is applied to a real track profile, measured in a Portuguese railway line, in order to understand the influence of the dynamic nature of the load on the track, the influence of the settlement rate and the influence of the type of vehicle on the evolution of the vertical track profile. The dynamic response of the track over time due to the evolution of the real vertical profile is evaluated through a vehicle-track dynamic-interaction approach. The attained results reveal the importance not only of the track irregularities, but also of the vehicle speed and characteristics on the evolution of the track profile. The numerical simulations presented in this paper evidence the potential of the proposed methodology, which can be used as a tool to forecast track settlement and to estimate the dynamic response of the track along the degradation process.

Explaining Heterogeneity in Pavement Deterioration: Clusterwise Linear Regression Model

Abstract: A clusterwise linear regression model of pavement deterioration is presented. The model provides a framework to simultaneously segment a population and to describe performance with a set of regression models, one for each segment. Instead of relying on observed criteria, the objective in the segmentation is to maximize within-segment variation explained by a set of commonly specified regression models. To illustrate the methodology, performance models were estimated for a panel of 131 pavements from the American Association of State Highway Officials (AASHO) road test. Pavements in different segments display systematic but unobserved differences in their responses, i.e., unobserved heterogeneity, which manifests itself in segment-level coefficients that differ in their magnitude and sign. This is radically different than other approaches in the literature that explain such differences with individual-level error/intercept terms, but that rely on the assumption of constant and homogeneous coefficie...

Management of Civil Infrastructure Systems: QFD-Based Approach

Abstract: Infrastructure owners or management agencies have well established quality control programs with the intent of achieving safe and effective maintenance. However, consumers are becoming more involved in economic, environmental, and social issues related to infrastructure. Therefore, a valid quality program would be more definitive by involving voice of the customer in the maintenance decision-process. In this paper, an innovative approach for achieving quality and customer satisfaction in infrastructure maintenance is proposed by implementing the quality function deployment (QFD) approach. Using bridges as an example, two separate applications of QFD have been proposed: (1) inspection prioritization, and (2) decision-making between replacement and/or rehabilitation scenarios. For both applications, an inspection house of quality is prepared for translating consumer demands (WHATs) into inspection requirements (HOWs) followed by prioritizing the inspection items (HOWs). For the inspection prioritization, hypothetical survey data is utilized. For the decision-making scenarios, a case study is furnished for a bridge located in Victoria, BC, Canada. The main conclusion as illustrated in the study is that QFD can be successfully adopted for improved management of civil infrastructure.

Cost-Benefit Analysis of Mobile Terrestrial Laser Scanning Applications for Highway Infrastructure

Abstract: This paper presents a cost-benefit analysis of mobile terrestrial laser scanning (MTLS), specifically in highway infrastructure (HI) applications using data and requirements from the western United States. MTLS can be used for rapid data collection in a digital point-cloud format. This data can then be analyzed for mapping and feature inventory in several applications including asset management, preservation, maintenance, and operational planning performed by State Department of Transportation agencies. In this paper, data and requirements related to some of the operations of Washington State Department of Transportation and the California Department of Transportation are used as the basis for this cost-benefit analysis.

Empirical Model with Environmental Considerations in Highway Alignment Optimization

Abstract: The highway alignment optimization (HAO) process is a complex combinatorial optimization problem in which several conflicting factors, such as highway costs, user preferences, and environmentally sensitive factors, must be simultaneously considered. In previous studies, single-level and bi-level optimization approaches were developed to optimize three-dimensional highway alignments. One drawback of previous approaches is that environmental factors, such as vehicular emissions, were not adequately considered in conjunction with other factors (such as user preferences and highway costs) in the optimization process. This paper builds on our previous studies and proposes two separate approaches for considering environmental emissions in the HAO process. The first approach involves a separate analysis of user and decision-maker preferences, in which a conceptual formulation of various environmental factors is presented. In the second approach, a novel tri-level optimization framework is proposed for optimizing highway alignments. At the upper level, optimization is performed using the traditional criteria of cost minimization. At the intermediate level, total systems emission is calculated. Finally, at the lower level, the user equilibrium traffic flow is optimized. The developed approaches are illustrated through case study examples. The proposed approaches will be beneficial for designing highway alignments when considering environmental emissions. Future studies may make additional refinements to the formulation and sensitivity analyses.

Pavement Maintenance Planning at the Network Level with Principal Component Analysis

Abstract: Pavement management relies on the evaluation of the condition of pavement at different times during the life of the structure. The combination of condition indicators and the knowledge of how they are used in any pavement condition model is fundamental for pavement rating. To handle complexity and information redundancy, this paper proposes the principal-component analysis (PCA) to evaluate the relative importance of different types of distresses on the condition assessment for flexible pavements, and to use relevant condition features to establish criteria for pavement management. The important outcomes in applying the PCA approach were: even with the dimensionality reduction dictated by the variance, there was limited loss of information with regard to the section condition that did not affect the overall objective of pavement management; also, information redundancy was minimized.

Managing Ancillary Transportation Assets: The State of the Practice

Abstract: Historically, transportation asset management has focused more on pavements and bridges, and less on ancillary assets such as traffic signs and guardrails. This paper synthesizes the state of practice of ancillary transportation asset management to assess the needs for successful implementation of such programs by highlighting data collection strategies and costs, data analysis tools, and data use in decision making, especially as it relates to asset prioritization and quantifying the benefits of ancillary asset management. The paper focuses on 10 asset classes selected from a review of literature: culverts, earth retaining structures, guardrails, mitigation features, pavement markings, sidewalks and curbs, street lighting, traffic signals, traffic signs, and utilities and manholes. The findings indicate that a number of agencies are making significant efforts to manage these assets with a range of asset management policies, system/program integration approaches, data collection methods and costs, benefit quantification, and asset category prioritization approaches. The results highlight the state of practice of managing ancillary transportation assets, revealing the dynamic nature of these activities as agencies evolve their activities to higher levels of program maturity.

Multiobjective Stochastic Inoperability Decision Tree for Infrastructure Preparedness

Abstract: Decision making for managing risks to critical infrastructure systems requires accounting for (1) the uncertain behavior of disruptive events; and (2) the interdependent nature of such systems that lead to large-scale inoperability. This paper integrates a dynamic risk-based interdependency model, the dynamic inoperability input-output model, with a multiobjective decision tree to analyze preparedness decisions. The use of a dynamic model allows for resilience and recovery decisions to be incorporated in the decision-making framework, and uncertainty is accounted for using probability distributions. The multiobjective inoperability decision tree is applied to the study of transportation infrastructure disruptions, namely closures of an inland waterway and an inland waterway port. A data-driven multiregional study of the Port of Catoosa in Oklahoma, along the Mississippi River Navigation System, is discussed and suggests careful consideration when investing larger amounts toward port security.

Comparative Analysis of Road Financing Approaches in Europe and the United States

Abstract: Road infrastructure has a remarkable economic and social impact on society. This is why road financing has always drawn the attention of policymakers, especially when resources available for government spending become scarce. Nations exhibit differing approaches to dealing with road transportation financing. In the United States, the current system of road funding has been called into question because some regard it as insufficient to meet the amounts now required for road expenditures. By contrast, in most European countries, road charges are very high, but these revenues are not allocated for the funding of roads. This paper analyzes the balance between charging for the use of and expenditure on the road sector in the United States and compares the American policy with those of several European countries (Germany, United Kingdom, France, Spain, and Switzerland). To that end, a methodology is defined to calculate the annual amount of fee charges levied on light and heavy vehicles in the selected countries in order to compare those charges with annual road expenditures. The results show that road charges in America are noticeably lower than those paid in Europe. Additionally, the research concludes that in Europe, road-generated revenues exceed road expenditures in all the countries studied, so road charges actually subsidize other policies. By contrast, in the United States, the public sector subsidizes the road system in order to maintain the current level of expenditure.

Identifying FDOT’s Physical Transportation Infrastructure Vulnerable to Sea Level Rise

Abstract: The objective of this research was to integrate current data sources to develop a methodology for assessing and mitigating the potential impacts of sea level rise (SLR) on Florida’s transportation infrastructure to assist transportation planning. The proposed approach integrates the Florida Department of Transportation (FDOT) information system with existing topographical and geological data to facilitate (1) the evaluation of current and projected SLR impacts on Florida’s coastline and low-lying terrain areas, and (2) the identification of the physical transportation infrastructure that is most likely to be affected by frequent to continuous flooding because of SLR so that solutions could be sought. The projection of SLR, and the timing for the same, was outlined using a benchmark approach that brackets time intervals as opposed to specific timing for improvements. Further research to evaluate the impact of sea level rise on ponding and storm surge is a future, more difficult area of investigation.

Financial Evaluation for Toll Road Projects Considering Traffic Volume and Serviceability Interactions

Abstract: The rapid increase in both financial demands and the need for large and comprehensive highway infrastructure systems necessitates public authorities to muster support from the private sector. Public-private partnerships (PPP) have been increasingly adopted and cited as one of the most effective project delivery systems, which bring balance to risks and rewards between involved project participants. However, a number of PPP infrastructure projects around the world have been reported to have operating deficits and difficulties in debt-servicing. One of the major reasons for these difficulties is the unrealistic and inaccurate prediction of project investment performance during the initial stages of project viability and profitability analysis. Therefore, the research reported in this paper presents a formulation of a comprehensive framework that evaluates financial viability of PPP toll road projects. The framework utilizes a modified user-equilibrium traffic-assignment algorithm to estimate toll road traffic volume considering critical demand-influencing factors, which include travel time, pavement serviceability, and out-of-pocket user trip expenses. The proposed framework also considers the effects of the rehabilitation maintenance activities on the equilibrium flow pattern and project financial viability. This makes possible an estimation of the maintenance costs and frequency as well as an evaluation of the effects of rehabilitation programs on the traffic volume. The research reported in this paper also demonstrates the difference in traffic-flow patterns with and without interactive changes in pavement performance and traffic volume to demonstrate the need for incorporation of pavement performance and network levels of service into PPP highway project evaluation.

Development of a Long-Term Bridge Element Performance Model Using Elman Neural Networks

Abstract: A reliable deterioration model is essential in bridge asset management. Most deterioration modeling requires a large amount of well-distributed condition rating data along with all bridge ages to calculate the probability of condition rating deterioration. This means that the model can only function properly when a full set of data is available. To overcome this shortcoming, an improved artificial intelligence (AI)-based model is presented in this study to effectively predict long-term deterioration of bridge elements. The model has four major components: (1) categorizing bridge element condition ratings; (2) using the neural network-based backward prediction model (BPM) to generate unavailable historical condition ratings for applicable bridge elements; (3) training by an Elman neural network (ENN) for identifying historical deterioration patterns; and (4) using the ENN to predict long-term performance. The model has been tested using bridge inspection records that demonstrate satisfactory results. This study primarily focuses on the establishment of a new methodology to address the research problems identified. A series of case studies, hence, need to follow to ensure the method is appropriately developed and validated.

Cost Optimization of Hydraulic and Structural Rehabilitation of Urban Drainage Network

Abstract: Urban drainage systems are prone to symptomatic decay that eventually causes surcharged flows and flooding, with important consequences for the aquatic ecosystems of receiving water bodies in addition to the safety of drinking water and recreational water activities. Rapid urban development and climate change combine with wear and tear along with a lack of network maintenance to accelerate this decay and cause a reduction in the hydraulic system’s capacity. In this context, the need for system rehabilitation becomes more pressing. Cost figures prominently take precedence in the decision-making surrounding the choice of rehabilitation method employed, but models for assessing cost-effectiveness which consider both structural and hydraulic options, in addition to real-world constraints and time-frame conditions, are lacking. This paper proposes an algorithm to maximize the benefits ensuing from the rehabilitation of urban drainage systems. Potential interventions considered in the algorithm include ...

Applying Multiobjective Bilevel Optimization under Fuzzy Random Environment to Traffic Assignment Problem: Case Study of a Large-Scale Construction Project

Abstract: This article presents an optimization method for solving a material flow traffic assignment problem (TAP) in a large-scale construction project considering a hierarchical structure with fuzzy random variables. A multiobjective bilevel decision-making model is established in which the transportation time and cost in each arc are considered as fuzzy random variables. The construction contractor, the leader in the hierarchy, aims to minimize both total direct and transportation time costs. The transportation agency, next in the hierarchy, assesses the target to minimize total transportation cost. To deal with the uncertainties, the expected value operator and chance constraint method are used to transform the uncertain model into a calculable one. Furthermore, a multiobjective bilevel particle swarm optimization algorithm with a fuzzy random simulation-based constraint checking procedure is applied to solve the model. Finally, the Shuibuya Hydropower Project is used as a practical example to demonstrate the practicality and efficiency of the proposed model. Results and a sensitivity analysis are presented to highlight the performance of the optimization method.

Relationships between Interdependency, Reliability, and Vulnerability of Infrastructure Systems: Case Study of Biofuel Infrastructure Development

Abstract: Infrastructure systems are becoming increasingly complex and interdependent, for example, the growing biofuel economy in the United States that is creating new interdependencies between agriculture, biorefining, and transportation. Questions arise of the consequences of these new and expanding interdependencies on overall system performance. This paper proposes the differentiation between linear and nonlinear interdependency that, though elementary, is useful for describing the joint behavior of interdependent systems. Linear interdependency is where representative variables of systems of interest change linearly with each other, while nonlinear interdependency is where the variables change with each other but in some other manner. This paper uses Pearson’s correlation coefficient to quantify the linear interdependency between the transportation and biorefining subsystems within a larger biofuel infrastructure system based on Monte Carlo simulation results of a mathematical programming model of th...

Application of Statistical Process Control for Structural Health Monitoring of a Historic Building

Abstract: The authors apply a statistical process control framework to support structural health monitoring of the Grace Church building in Charleston, South Carolina. Specifically, they conduct a post-hoc analysis of displacement data acquired via remote monitoring of delamination between two wythes of brick in a clerestory wall. The framework consists of formulation and estimation of statistical models to explain the progression of the measurements under ordinary conditions and use of control charts to detect unusual events. One such event was excessive displacement in September 2011 that led the engineer of record to close the building to public access and order immediate repairs. The analysis also reveals a few unusual events that were not apparent from visual interpretation of the data, including a possible precursor to the aforementioned event.