Showing papers in "Journal of Infrastructure Systems in 2004"

Life-cycle energy analysis of a water distribution system

Abstract: The paper presents a life-cycle energy analysis (LCEA) to quantify energy expenditures in the fabrication, use, and end-of-life stages of the pipes of a water distribution system. The methodology incorporates the capabilities of environmental input-output life-cycle analysis to quantify the energy required to fabricate pipes. The EPANET2 hydraulic model is applied in conjunction with a pipe-aging model to calculate the theoretical energy recovery in the use stage. An exponential pipe-break model is applied to quantify the energy required to repair pipe breaks during the use stage of a system. Simple formulations are developed to estimate the energy required to dispose of and recycle pipes once their service period has expired. The LCEA methodology is then applied to the New York City (NYC) water supply tunnels example to quantify energy expenditures in four planning scenarios with 10-, 20-, 50-, and 100-year pipe replacement frequencies. The results of the NYC example highlight the tension between the energy costs incurred in the fabrication and end-of-life stages of a system and those incurred in the use stage. A pipe-replacement period roughly equal to 50 years yielded the lowest overall energy expenditure in the three life stages. A sensitivity analysis was carried out to assess the influence of uncertain system parameters on energy expenditure estimates.

Highway Development Decision-Making under Uncertainty: A Real Options Approach

Abstract: A highway system development involves huge irreversible investments, and requires rigorous modeling and analysis before the implementation decision is made This decision-making process is embedded with multiple uncertainties due to changes in political, social, and environmental contexts In this paper, we present a multistage stochastic model for decision making in highway development, operation, expansion, and rehabilitation This model accounts for the evolution of three uncertainties, namely, traffic demand, land price, and highway deterioration, as well as their interdependence Real options in both development and operation phases of a highway are also incorporated in the model A solution algorithm based on the Monte Carlo simulation and least-squares regression is developed Numerical results show that the proposed model and solution algorithm are promising This model makes a radical and conceptual step towards optimal decision making in highway engineering, which achieves decision-making optimality that is generally not well defined in traditional policy-based approaches for highway planning

Development of Pavement Performance Models by Combining Experimental and Field Data

Abstract: The objective of this paper is to demonstrate the development of pavement performance models by combining experimental and field data. A two step approach was used. In the first step a riding quality model based on serviceability consideration is developed. The data set of the American Association of State Highways Officials (AASHO) Road Test is used to this effect. Due to the experimental nature of the AASHO Road Test data set, some of the estimated parameters of the model may be biased when the model is to be applied to predict performance in the field. In the second step, the original model parameters are reestimated by applying joint estimation with the incorporation of field data set. This data set was collected through the Minnesota Road Research Project (MnRoad). The final model is referred to as the joint model, and it can be used to predict the performance of in-service pavement sections. Joint estimation allowed for the full potential of both data sources to be exploited. First, the effect of variables not available in the first data source were identified and quantified. Further, the parameter estimates had lower variance because multiple data sources were pooled, and biases in the parameters of the experimental model were corrected. Finally, different measurements of the same property were incorporated by using a measurement error model. Thus, the methodology proposed in this paper makes optimum use of available data and yields models of improved statistical properties compared with techniques such as ordinary least squares.

Soft Computing Applications in Infrastructure Management

Abstract: Infrastructure management decisions, such as condition assessment, performance prediction, needs analysis, prioritization, and optimization are often based on data that is uncertain, ambiguous, and incomplete and incorporate engineering judgment and expert opinion. Soft computing techniques are particularly appropriate to support these types of decisions because these techniques are very efficient at handling imprecise, uncertain, ambiguous, incomplete, and subjective data. This paper presents a review of the application of soft computing techniques in infrastructure management. The three most used soft computing constituents, artificial neural networks, fuzzy systems, and genetic algorithms, are reviewed, and the most promising techniques for the different infrastructure management functions are identified. Based on the applications reviewed, it can be concluded that soft computing techniques provide appealing alternatives for supporting many infrastructure management functions. Although the soft computing constituents have several advantages when used individually, the development of practical and efficient intelligent tools is expected to require a synergistic integration of complementary techniques into hybrid models.

Effectiveness of ground penetrating radar in predicting deck repair quantities

Abstract: Ground penetrating radar (GPR) was examined as an alternative or supplement to visual inspection methods for predicting reinforced concrete bridge deck repairs. Visual inspection has frequently resulted in grossly inaccurate estimates of repairs causing large maintenance cost overruns. GPR-predicted deteriorations were compared to deterioration detected using the chain drag and half-cell potential methods on 24 asphalt covered reinforced concrete decks exhibiting a broad spectrum of deterioration levels. The differences among the deterioration quantities resulting from these surveys were normalized for comparison with respect to the deterioration area and deck size. Large proportions of all decks surveyed containing less than 10% and more than 50% deterioration of the total deck surface area (as measured by chain drag) exhibited significant differences between the GPR and both ground-truth survey quantities. Insignificant differences between GPR predictions and the ground-truth results were observed for six out of seven decks exhibiting deterioration levels between 10 and 50% (by chain drag). It is concluded from this investigation that a combination of visual inspection and GPR inspection surveys for all decks can improve repair estimates and reduce the occurrence of gross underestimates of repair quantities.

Fuzzy-Based Method to Evaluate Soil Corrosivity for Prediction of Water Main Deterioration

Abstract: A fuzzy-based method is proposed to evaluate soil corrosivity from soil properties such as soil resistivity, pH, redox potential, sulfide content, and soil type. The fuzzy-based method considers three levels of soil corrosivity, noncorrosive, moderately corrosive, and corrosive. This is in contrast to the commonly used 10-point scoring (10-P) method that has only two classes, corrosive and noncorrosive. Membership functions for each of the soil properties are used to quantify their affinity to the level of soil corrosivity. These membership values form an evaluation matrix from which a weighted vector is developed using pair-wise soil property comparisons. The final classification is determined from the cross product of the weighted vector and the evaluation matrix. Two case studies are examined to validate the application of the proposed fuzzy-based method to predict soil corrosivity, and the results are compared to the 10-P method. Both case studies showed that the fuzzy-based method outperformed the 10-P method.

Holistic strategy for urban security

Abstract: Since September 11, 2001, the vulnerabilities to terrorism of our urban areas, and how best to address them, have been subject to considerable discussion, debate, and reflexive defensive measures. Although direct physical responses to such frightening events are certainly understandable, they are not based on a true assessment of risk, nor do they necessarily represent an effective, let alone cost effective, approach to addressing the threat of urban terrorism. This paper will explore recent trends in physical protection and offer observations on a rational basis for evaluating security strategies; some alternative, nonstructural approaches to urban security, and the need for robust institutions with well-qualified people in critical positions to develop and implement these strategies. It will seek to demonstrate that a holistic strategy that incorporates technology, people, and institutions will achieve far greater long-term security as well as possible ancillary mitigation benefits from other hazards.

Greenhouse gas emissions from coal gasification power generation systems

Abstract: Life cycle assessments (LCA) of coal gasification-based electricity generation technologies for emissions of greenhouse gases (GHG), principally CO2, are computed. Two approaches for computing LCAs are compared for construction and operation of integrated coal gasification combined cycle (IGCC) plants: a traditional process-based approach, and one based on economic input-output analysis named Economic Input-Output Life Cycle Assessment (EIO-LCA). It is shown that EIO-LCA provides a more complete accounting for emissions incurred during construction resulting in larger estimates of emissions. For plant construction process-based LCA computes emissions that approximate a subset of emissions computed via the EIO-LCA method. For plant operation, however, only emissions due to mining and consumption of coal at the plant are significant, and both methods of analysis give essentially equivalent results. For conventional coal-based power generators, and even for those that would capture 90% of carbon emissions, GHG emissions during a typical operating life of 30-50 years dominate the life cycle. Literature values for life cycle emissions of GHGs for a number of renewable technologies are compared to emissions from IGCC systems with and without carbon capture and from natural gas combined cycle (NGCC) without capture. Lowest life cycle emissions are achieved with dammed hydro power and wind farms. IGCC with 90% CO2 capture exhibits lower life cycle GHG emissions than NGCC and solar photovoltaic systems.

Network Electricity Use Associated with Wireless Personal Digital Assistants

Abstract: This article examines the widely cited claim that the network electricity use associated with a wireless personal digital assistant (PDA) is equal to the electricity consumed by a refrigerator. It compiles estimates of the data flows of wireless PDAs and related networks and allocates network and phone system electricity use based on these estimates. It also conducts sensitivity analyses to verify the robustness of these calculations. This analysis demonstrates that the network electricity use associated with a wireless PDA cannot equal that of a typical refrigerator, even under the most extreme assumptions. Our best-estimate case shows network electricity use for wireless PDAs of 0.5 kW⋅h/year, and therefore claims that wireless PDAs use as much electricity as a refrigerator are too high by more than a factor of 1,000. Even in our upper-limit assessment, the electricity used by a new U.S. refrigerator is about 100 times greater than the network electricity use associated with a wireless PDA.

Maintenance and repair decision making for infrastructure facilities without a deterioration model

Abstract: In the existing approach to maintenance and repair decision making for infrastructure facilities, policy evaluation and policy selection are performed under the assumption that a perfect facility deterioration model is available. The writer formulates the problem of developing maintenance and repair policies as a reinforcement learning problem in order to address this limitation. The writer explains the agency-facility interaction considered in reinforcement learning and discuss the probing-optimizing dichotomy that exists in the process of performing policy evaluation and policy selection. Then, temporal-difference learning methods are described as an approach that can be used to address maintenance and repair decision making. Finally, the results of a simulation study are presented where it is shown that the proposed approach can be used for decision making in situations where complete and correct deterioration models are not (yet) available.

Modeling interdependent infrastructures for sustainable counterterrorism

Abstract: If the adage ‘‘to manage risk, one must measure it’’ constitutes the compass for risk management, then risk models provide the roadmaps that guide the analyst throughout the journey of risk assessment. The process of risk assessment and management may be viewed through many lenses, depending on the perspective, vision, values, and circumstances. This forum addresses the complex problem of developing tactical and strategic responses to the risks of terrorism. As a vehicle with which to communicate a framework for modeling, we focus on the risks facing the United States, while recognizing that a more complete analysis would include the entire world community.

Quantifying Effectiveness of Cathodic Protection in Water Mains: Theory

Abstract: Cathodic protection is a viable measure to extend the residual life of water mains and thus defer capital investments in their rehabilitation and renewal The effectiveness of cathodic protection varies with the unique set of conditions under which it is applied, and it is difficult to confirm or validate whether its application can be considered successful Therefore, the reported success histories have been largely anecdotal and most often based on the reduction of water main breaks using cathodic protection This paper describes methodologies and associated models to quantify and assess the performance of cathodic protection programs implemented by water utilities The effectiveness of cathodic protection programs applied under various conditions can be determined and weighed against their costs in order to maximize the benefit from their implementation These proposed methodologies and models should assist water utilities to optimize the implementation and scheduling of future cathodic protection programs A companion paper, Quantifying Effectiveness of Cathodic Protection in Water Mains: Case Studies, describes the application of proposed models to assess the impact of cathodic protection programs

Life-Cycle Cost Award Algorithms for Design/Build Highway Pavement Projects

Abstract: The nation’s existing highway infrastructure was procured on a low bid basis. The recent trend towards design-build delivery offers an opportunity to compete life cycle consideration in procurement. Minimizing pavement life cycle cost will enhance the sustainability of the nation’s highways by delivering pavements that last longer and reduce waste. This study provides best-value award algorithms that can be used to procure pavement on the basis of life cycle cost rather than low bid initial costs. The study uses the Federal Highway Administration (FHWA) life cycle cost analysis (LCCA) design algorithm as a basis of the best-value award.. Two detailed case study projects were used to furnish input data and information on which to base the comparison of bestvalue award algorithms. The analysis proves that many of the current best-value award algorithms currently used in design-build projects have a strong bias to minimize the capital cost of design and construction. The analysis also shows that the LCCA input can be used, but must be heavily weighted to influence the final award decision away form the lowest proposed price.

State-of-Practice of Warranty Contracting in the United States

Abstract: This paper presents the results of a comprehensive survey on warranty practices in the United States and a summary of the impact of warranty implementation on highway projects, based on questionnaire responses and interviews of State Department of Transportation (DOT) representatives, contractors, and surety companies According to the results of the survey, the initial bid price increases due to warranty provisions are estimated to be somewhere between 0 and 15%, while the changes in maintenance and project life-cycle costs are expected to be minimal Warranty provisions increased the quality of the projects and reduced the need for site inspection and record keeping for state DOTs The study also revealed the unwillingness of surety companies to underwrite small contractors when the project calls for long term warranty durations

Life-Cycle Impact Analysis of Energy Systems for Buildings

Abstract: Cogeneration systems offer an opportunity to satisfy a building’s electrical and thermal loads, which could result in an overall energy efficiency improvement and lower environmental impact. Hourly energy simulation and a life-cycle assessment framework are used to evaluate the relative environmental impacts and energy efficiencies of the construction and operation of alternative technologies for providing space and domestic water heating, cooling, and electrical power for equipment and lights in buildings. Life-cycle comparisons are presented for current practice (average U.S. power generation mix, electric chillers, and gas-fired boilers), high-efficiency natural gas combined-cycle power generation, and three building-integrated combined heat and power (CHP) technologies. The analysis demonstrates (1) a framework that supports decision making regarding system selection and operational strategies to limit environmental impact; (2) the importance of a life-cycle assessment framework, illustrated by the an...

Economic and Environmental Evaluation of Residential Fixed Solar Photovoltaic Systems in the United States

Abstract: While the majority of electricity generated in the United States comes from fossil fuels such as coal and natural gas, a comparatively small amount comes from renewable sources such as solar and hydropower. As global environmental issues become a greater concern, more generation may need to come from renewable sources. One often-mentioned alternative is residential solar photovoltaic (PV) systems, which could be an especially attractive source of energy in the southwestern United States, where high amounts of solar radiation are available. In this paper, we compare the life-cycle costs of current solar photovoltaic technology in Arizona versus New York to highlight the relevant issues related to the economic and environmental renewable energy decision-making process. We find that solar PV systems alone are currently inferior to grid electricity across a wide range of scenarios, including prospective technology improvements. Net metering with PV systems, where customers sell solar electricity to the grid and buy back their demand, may be competitive given real-time electricity pricing. Using PV systems in remote systems looks to be a viable alternative.

Data Centers Revisited: Assessment of the Energy Impact of Retrofits and Technology Trends in a High-Density Computing Facility

Abstract: As information and communications technology matures, the nature of the infrastructure that supports it evolves and specializes. While the telephone infrastructure had been built as a network with central offices acting as hubs, the information and communications technology maintains a similar structure, but instead, has hubs of specialized Internet data centers which house the routers and servers. This paper updates one of the first studies to document the electricity consumption and power distribution within an Internet data center. For this study, electricity billing data, metering data, and facility floor space allocation data were used to calculate computer room, total computer room, and building power densities for July 2002. The results of this 2002 study indicate that although the data center had expanded its operations by roughly 33% from the previous year and increased the electricity demand associated with the computer equipment by 55%, the total computer room power density (which includes cooling and auxiliary equipment) remained the same as the previous year at 355 W/m2. The facility’s efforts to improve energy efficiency offset the energy demand from an increased, electrically active, computer room area. The energy-efficiency measures included better optimization of power distribution units, power management modules, computer room air-conditioning units, alterations to operating conditions, facilitywide reductions in lighting, and improved facility controls. A key recommendation is to expand this research to address the need to develop metrics to capture the energy efficiency of the data network throughput.

Advancing Sustainable Development of Infrastructure Systems

Abstract: Sustainability is a concept born from the global movement toward better management of resources. A 1987 United Nations World Congress document ~called the Brundtland Report! defined sustainability as ‘‘management of resources such that current generations are able to meet their needs without affecting the ability of future generations to meet their needs.’’ This definition of sustainability has led experts in many disciplines—technical and social—to call for an increased concern for environmental and resource management within their fields. However, practical interpretations of this definition are still largely missing. These interpretations are mostly being advanced by academic researchers and have yet to be incorporated into corporate and governmental structures. Indeed, leaders in engineering, chemistry, economics, and philosophy have translated this concept of sustainability into a call for action. The field of civil and environmental engineering, while not a primary player in the sustainability movement, has not been idle. The ASCE Committee on Sustainability was formed in 2001 and includes a cross section of ASCE’s membership profile. For the past 2 years, there has been one session at the ASCE National Conference on the topic of sustainability in civil engineering, including discussions on the role of sustainability in civil and environmental engineering education. The 2003 ASCE Construction Research Congress had two sessions on sustainability, and more are planned for the 2005 meeting. The May 2004 ASCE Structures Congress included one session on economic and environmental life-cycle assessment. These efforts are a good professional starting point, but should not be seen as sufficient to enable the levels of change needed. The National Science Foundation—a primary source of funding for engineering research in the United States—has been supportive of sustainable engineering projects, including the Division of Civil and Mechanical Systems in the Engineering Directorate. Programs from the U.S. Department of Energy and the EPA have also been supportive of this area over the past decade. Current national environmental priorities are not necessarily in line with global sustainability goals. For example, United States policy is currently dubious of the implications and causes of global climate change from greenhouse gas emissions and atmospheric concentrations. The United States is not a player in the official global Kyoto Protocol implementation to reduce emissions to below 1990 levels. This could have the undesirable side effect of undermining our leadership positions in global environmental management, as well as in the development of environmental control technologies. Europe and Asia are poised to take over these leadership positions without further American efforts

Infrastructure in the Anthropocene: Example of Information and Communication Technology

Abstract: As a recent Nature ~2003! editorial put it, ‘‘Welcome to the Anthropocene,’’ the era of the anthropogenic Earth in which the dynamics of many major natural systems increasingly reflect the activities of a single species ~Allenby 2000/2001! ~B R Allenby, unpublished working paper, Batten Institute, Univ of Virginia, 2002! Indeed, it is increasingly apparent that a principle result of the Industrial Revolution and associated changes in human demographic patterns, technology and economic systems, and cultures, is a continuing, indeed accelerating, integration of many natural and human systems at all scales, including the global, with concomitant emergent behaviors and increasingly complex and coupled dynamics Under these conditions, continued stability of both human and natural systems will require development of an earth systems engineering and management capability, which can be defined as the ability to rationally engineer and manage coupled human-natural systems in a highly integrated fashion Thus framed, it is apparent that the need for earth systems engineering and management has not arisen from any particular project, issue, or perturbation but is rather a reflection of a new stage in the evolution of earth systems, including human systems such as economies, flows of energy and materials, institutional and cultural organization, and built infrastructures of many kinds This perspective raises a challenging question for engineers: Under such circumstances, what is infrastructure? To begin with, it is apparent that the kinds of things we traditionally think about as infrastructure—transportation networks and water and sewage systems—clearly remain important, but emergent behavior, as these built systems integrate in ever more complex ways with the natural environment and other human systems at higher scales, becomes increasingly important and increasingly reflective of human activities Systems that are considered ‘‘natural,’’ ranging from the elemental cycles of carbon and nitrogen to the hydrologic cycle, are increasingly integrated with infrastructure systems For example, genetic engineering is integrating previously independent biological systems—in this case, biological structures at the genomic level—into food production and, through politics, food distribution systems The global climate change negotiations are, in part, a mechanism by which portions of the carbon cycle are brought into the human economic system and made human, and the fossil fuel energy infrastructure and automotive infrastructure play important roles in this The evolution of ‘‘intelligent infrastructure’’ creates new and complex patterns of interactions among previously disparate infrastructures, as well as between infrastructure and the natural systems they affect

Minimizing Network Disruption for Planned and Emergency Repairs of Water Supply Systems

Abstract: Urban water supply systems are typically large, complex, and expensive to build and maintain. Disruptions of service can have serious implications on the economy, health, and convenience of those served by the system. Consequently, improved system performance and customer service are important goals of water supply system managers. However, even in the most advanced systems, water supply must be disrupted to some customers due to emergency situations or planned maintenance. In this paper, we present an optimal algorithm to minimize the network impacted when such a disruption occurs. The algorithm can be readily incorporated into sophisticated decision support systems for water supply network planning and management.

Privatization of Municipal Services: Sustainability Issues of Production and Provision

Abstract: Privatization is an accepted strategy to improve the economic efficiency and quality of services provided by municipal infrastructure. However, the impact of using the private market to allocate public resources has not been adequately researched. In this paper, the effects of the privatization of municipal services as public policy are assessed. The assessment is based on a detailed review of the privatization literature across disciplines and a more focused analysis of efforts in two cities. The supporting literature emphasizes that municipal infrastructure decisions play a big role shaping a community; therefore local government needs to maintain accountability to its citizens. Maintaining accountability for essential municipal services while having flexible financing options may require the separation of the production of a service from the provision of that service. The examples from the two cities agree with these conclusions and demonstrate that concessions are the preferred privatization strategy for essential municipal services. The examples also provide a variety of creative strategies to enhance the competitive environment for concessions.