Journal of Infrastructure Systems

This paper proposes a general approach for risk assessment and management of marine pipeline infrastructures. The system is identified as RAM PIPE REQUAL. The approach is based on use of qualitative (level 1), quantitative (level 3), and mixed qualitative-quantitative (level 2) analytical methods. The approach, its attributes, and its strategies are summarized. A computer database pipeline integrity, maintenance, and performance information system is described, and data provided by the U.S. Minerals Management Service on pipelines in the Gulf of Mexico are analyzed to determine the primary factors involved in past losses of containment. The level 2 approach for assessment of pipelines subjected to corrosion is applied to requalification of a pipeline in the Bay of Campeche. It is concluded that RAM PIPE REQUAL is a practical and effective process for risk-based management of marine pipeline infrastructure.

Deterioration of underground infrastructure facilities such as sewer pipes poses a serious problem to most developed urban centers today. As distribution piping networks age, they deteriorate and may ultimately fail to fulfill their intended functions. To ensure continuity of services and protect the investment made in these networks, municipalities check their conditions regularly. The current practice that is being followed in those checkup programs is usually time consuming, tedious, and expensive. This paper presents an automated system designed for detecting defects in underground sewer pipes and focuses primarily on the application of neural networks in the classification of those defects. A three-layer (i.e., one hidden layer) neural network has been developed and trained using a back-propagation algorithm to classify four categories of defects, namely cracks, joint displacements, reduction of cross-sectional area, and spalling. A total of 1,096 patterns were used in developing the neural network. An example application is described to demonstrate the use and capabilities of the developed system.

Trenchless technology (TT) consists of a wide range of methods to install or rehabilitate existing underground pipelines with minimal excavation of the ground. In the past, excavation was used almost exclusively to restore old and deteriorated sewers and water pipelines. However, as cities become more congested, the disruption and expense associated with excavation becomes less acceptable. The development, selection, and utilization of TT have expanded rapidly over the past ten years. The benefits of TT are quite apparent when compared to the conventional open-cut process. However, it is necessary to evaluate the suitability and appropriateness of any rehabilitation system, trenchless or otherwise, on a project-by-project basis through consideration of all project criteria such as site conditions, geotechnical conditions, condition of existing pipeline, design life of new pipe, etc. This paper presents a decision support system to assist design engineers and sewer system managers in selecting the most appropriate technology for a project by systematically evaluating groups of criteria with respect to the knowledge-based preference of the user and the project-specific situation.

One key element of our nation's infrastructure is our communities' drinking water supplies. Growing consumption by expanding populations, industrial and public pollution, the tragedies of both nature and human accidents, and the emergence of threats by domestic terrorists, disgruntled employees, and computer hackers continue to torment the nation. Add to these concerns the anxiety over Y2K failures of the utilities that control these systems; they all pose potential perils to freshwater reserves that local municipalities, state, and federal governments are obligated to protect. This paper serves to introduce the probabilistic infrastructure risk analysis model developed for a small community's water supply and treatment systems. The paper adopts a holistic approach to model a water infrastructure system's interconnectedness and interdependencies. This approach can also be used for other interconnected infrastructure elements such as physical facilities, electric power generation and distribution, and telecommunications. Insurance companies, municipal managers, utility companies, etc., can use this technique to develop scenarios and quantify the value of countermeasures.

The purpose of this paper is to present an application of the infrastructure risk analysis model to a small municipality. The paper begins by decomposing the water system along the dimensions of function, component, structure, state, and vulnerability, while considering other perspectives such as political, temporal, threat, and economic. Component vulnerability is subjectively assessed in terms of exposure and access. Based on vulnerability analysis and expert opinion, a willfull water contamination attack scenario is developed and then modeled using an event tree. Expected and extreme risk are then measured using exceedence probability. Lastly, alternatives are generated and the results are presented in a multiobjective framework. The methodological framework presented can easily be applied to other critical infrastructure elements and networks.