Journal of Infrastructure Systems

The terrorist acts of September 11, 2001, were a wake-up call for changing our past practices in ensuring homeland security. The positive results of these changes, however, are accompanied by myriad visible and invisible risks. Accepting change implies assessing and managing these risks in a comprehensive and systemic fashion, avoiding an ad hoc approach. This paper offers a holistic risk assessment and management framework for modeling the risks of terrorism to the homeland. Two major interconnected systems are addressed: the homeland system and the terrorist networks system. In modeling the two systems, the centrality of state variables is highlighted. It is worth noting that the community of risk analysts has been developing and applying systems-based methodologies and tools for many years. The roadmap presented in this paper builds on the findings of many prior analyses.

In project planning, several design concepts are considered to examine the potential to lower the lifecycle costs of the structure without sacrificing significant performance. Various natures of unusual and extreme events should be considered, and the nature and frequencies of such events may not yet be known. In addition, the details of design alternatives in early feasibility stages may not yet be specified. The identification of multiple stakeholders (e.g., local, regional, and national interests) may not be complete. A cost-benefit analysis would require complete knowledge of design alternatives, event frequencies and impacts, and stakeholders. A process is developed in this work to explore the costs and performance of preliminary design concepts for infrastructure projects that are vulnerable to several extreme events that would have an impact to multiple stakeholders. An example with inland navigation lock walls subjected to barge impacts and earthquake loads is provided. Complementary performance metrics that are applied include repair cost, time to recover, and cost to industry. Several magnitudes and frequencies of event scenarios are characterized, and some relevant features of a software tool developed for preliminary design evaluation of navigation lock walls are described.

Effective management of storm water pipe networks requires an accurate assessment of the structural condition of the pipes. Indeed, the recent introduction of Australian accounting standard AAS27 compels local governments to prepare annual financial statements, including the depreciated value of their storm water network. A rational approach to assessing depreciation is to base it on structural deterioration. This study presents a Markov model for the structural deterioration of storm water pipes. The model is calibrated, using Bayesian techniques, to structural condition data from the storm water asset database of the Newcastle City Council (Australia). It is shown that the Markov model is consistent with the data. The pipe characteristics of diameter, construction material, soil type, and exposure classification were found to influence the deterioration process. It is also shown that the depreciation methods required by AAS27 significantly overestimate the structural deterioration.

This paper presents the methodology developed for assessing the safety and traffic operational quality of 92 stone arch bridges within Hunterdon County, New Jersey. The methodology presented here was developed as part of a study conducted to provide recommendations on the maintenance and preservation of these bridges. As part of that study, four components were evaluated: traffic safety, traffic operational quality, structural stability, and historic significance. This paper focuses on the safety and traffic operational aspects of the study, and illustrates the methodology developed for quantifying them. To assess traffic safety, three different rating systems were used to quantify traffic safety operations, and rate the structures in their priority for improvements. The three traffic rating systems used were a comparison with current AASHTO design policy, the Bridge Safety Index developed at the Texas Transportation Institute, and the Widening Priority Rating developed by the writers. To assess traffic operational quality at these bridges, the Highway Capacity Manual methodology for two-lane highways was used, along with a queuing analysis method developed by the writers for narrow one-lane bridges. The traffic safety and traffic operational quality ratings were used in conjunction with historic significance information to produce a set of preservation recommendations for every structure.