The reliable functioning of infrastructures is critical to national security and fundamental to social, economic, and environmental well-being. Cascading failures due to the interdependencies among different critical infrastructures (CIs) have been observed in many events (e.g., Hurricanes Harvey, Irma, and Maria in 2017). While different modeling approaches have been used to capture different infrastructures or different aspects of interdependent CIs, a strategic framework is needed to integrate different modeling approaches based on their unique capabilities. It is also critical to validate modeling approaches in a uniform framework and disseminate the framework to the stakeholders in an easy and understandable way. This research aimed at developing an integrative decision making framework with consideration of physical-based, virtual-based, and socioeconomic-based interdependencies between water, transportation and cyber infrastructures that help urban planners, infrastructure managers, and policy makers for evaluating strategies to enhance the resiliency of interdependent critical infrastructures. To achieve the project goal, our research team developed various models including a finite element model to analyze the responses of buried water pipes to vehicle loads, multi-layer network models to investigate the stress propagation within and across modeled infrastructures, and simulation and optimization models to identify critical elements in modeled infrastructures and effective restoration strategies during and post-failures/disaster. The model results were validated using historical data, field data and information provided by the stakeholders. In addition, the insights on organizational resilience of CIs were gained through stakeholder interviews, a comprehensive online survey, and a social vulnerability analysis. Most importantly, the outcome from the developed models and the organizational resilience study were integrated in various ways including a joint maintenance decision-making framework to evaluate and optimize co-located water and transportation infrastructure maintenance policies, a resilience assessment framework to identify the vulnerable areas prone to cascading failures, a coalitional game theory approach to address decentralized resource allocation for interdependent water distribution and road networks, and a hybrid system dynamics and agent-based modeling approach to quantify aggregated resilience indicator and explore potential communication, financial, and learning strategies to enhance the resilience and adaptive capacity of the CIs and their relevant organizations. Through our studies, we learned that 1) the impact of heavy vehicles on water pipes can be ignored and the interdependency between water distribution network and road is more unidirectional from water infrastructure to road, 2) the influence of the interdependency between water and road infrastructures becomes more significant as the magnitude of water infrastructure failure increases beyond a threshold, 3) low-income areas and communities of color in Tampa had low resilience capacity (high levels of social and environmental vulnerabilities, hydraulic vulnerability, and infrastructure interdependency), 4) infrastructure interdependency and the consequences of cascading failures and socioeconomic factors should be taken into account in resilience assessment for a comprehensive and equitable resilience planning, 5) the resilience of water distribution infrastructure can be improved through gradual pipe diameter change along flow paths and higher loop nestedness, 6) a higher investment in road infrastructure could help reduce unmet demand through more restoration options, 7) decentralized, cooperative decision-making is an effective approach to find the resource allocation solutions for interdependent CIs, 8) the proposed joint maintenance planning strategy for interdependent CIs is more cost-saving compared with several existing benchmark strategies, and 9) the strategies focusing on proactive maintenance and effective communication (intra- and inter-departments) improve the resilience of interdependent CIs. Our research team collaborated with the City of Tampa Water Department, City of Tampa Transportation Management Center, City of Tampa Stormwater Services, Department of Technology and Innovation, City of Tampa Wastewater Department to contextualize our studies, obtain the input and feedback, and communicate the findings. The project fully or partially supported two (2) female postdocs, fifteen (15) doctoral students, and three (3) master’s students. Our research team published four (4) doctoral dissertations, one (1) MS thesis, seventeen (17) peer reviewed journal articles, and one (1) technical report. Five (5) journal articles are currently under review and five (5) are in preparation. In addition, the findings from the study were presented at stakeholder meetings, local events, and forty-five (45) local, national and international conferences.

Last Modified: 09/15/2022
Modified by: Qiong Zhang