Selecting asset protection strategies: a comparison of optimization and ranking

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University of Delaware
Transportation infrastructure is exposed to several kinds of unintentional (natural) and intentional (attacks) hazards. Keeping the transportation system working before and after a severe event is a vital task of transportation agencies. In the past decade, transportation agencies have used an asset management framework to support the improvement, maintenance and operation of transportation facilities. So, risk analysis and management is an essential part of any asset management framework. Choosing the appropriate countermeasures to prevent, mitigate and control the risk of severe events is an important activity in the risk management process. A recent National Cooperative Highway Research Program (NCHRP) report provides a guide for transportation agencies to select appropriate countermeasures to protect their critical assets. However the selection of countermeasures is completely qualitative and subjective. This thesis develops a quantitative system to evaluate the effectiveness of countermeasures. Moreover, budget constraints are always a limitation for transportation agencies and this is not addressed in the NCHRP guide. The problem of choosing countermeasures is redefined as ―selecting the most effective countermeasures considering the budget constraint‖. This problem is formulated as an optimization problem. The objective of the optimization problem is to maximize the effectiveness of the selected set of countermeasures. This objective is subject to a budget constraint. A conventional optimization solution method is applicable to this problem. A case study using bridges in the state of Delaware is developed and the results of the new method are compared with the result using NCHRP guide. The optimization method shows significant improvements over the qualitative method in terms of the effectiveness of protection of the bridges.