Abstract
We present a methodology, Preliminary Interdependency Analysis (PIA), for analysing interdependencies between critical infrastructure (CI). Consisting of two phases – qualitative analysis followed by quantitative analysis – an application of PIA progresses from a relatively quick elicitation of CI-interdependencies to the building of representative CI models, and the subsequent estimation of any resilience, risk or criticality measures an assessor might be interested in. By design, stages in the methodology are both flexible and iterative, resulting in interacting CI models that are scalable and may vary significantly in complexity and fidelity, depending on the needs and requirements of an assessor. For model parameterisation, one relies on a combination of field data, sensitivity analysis and expert judgement. Facilitated by dedicated software tool support, we illustrate PIA by applying it to a complex case-study of interacting Power (distribution and transmission) and Telecommunications networks in the Rome area. A number of studies are carried out, including: 1) an investigation of how “strength of dependence” between the CIs’ components affects various measures of risk and uncertainty, 2) for resource allocation, an exploration of different, but related, notions of CI component importance, and 3) highlighting the impact of model fidelity on the estimated risk of cascades.
Highlights
It is recognised that one of the challenges in enhancing the protection of Critical Infrastructures1 (CIs) against accidents, natural disasters, and acts of terrorism is establishing and maintaining an understanding of the interdependencies between infrastructures
Faced with numerous choices about model structure, fidelity and parameters, our assessor can gain confidence in a model by a succession of model refinements, each refinement resulting from verifying and validating an earlier version of a model and making judgements about what changes to the model are needed for an improvement while, at the same time, not putting in more detail than she judges to be necessary for her needs
Based on our experience, building Stochastic Activity Networks (SAN) models from scratch for every new case-study ’does not scale’ up – for scenarios of typical complexity it is time consuming, error prone and can be difficult to debug. We addressed this difficulty by developing a tool support, based on SAN formalism and ASCE tool, which complements Preliminary Interdependency Analysis (PIA), and which is briefly summarised in the introduction and its use is demonstrated in the appendix
Summary
It is recognised that one of the challenges in enhancing the protection of Critical Infrastructures (CIs) against accidents, natural disasters, and acts of terrorism (including cyber terrorism) is establishing and maintaining an understanding of the interdependencies between infrastructures. Any methodology/tools which support an assessor in this endeavour should afford the assessor the flexibility to (1) create models at any desired level of abstraction, (2) alter/add/remove stochastic and deterministic processes, and (3) define any risk-measure of interest To this end, we propose Preliminary Interdependency Analysis (PIA) – a systematic method to support building, refining and analysing models of interdependent Large Complex Critical Infrastructures (LCCI). PIA starts off at a high-level of abstraction, supporting a cyclic, systematic thought process, directed towards identifying dependencies between components of CIs. Eventually, (hybrid) probabilistic models are deployed, once they have been judged to be appropriate for risk-assessment; these are used to conduct studies focussed on computing different measures of interests, e.g. the likelihood of cascade failure under a given set of assumptions, or the identification of the weakest link in the modelled system. Appendix A contains a detailed illustration of model development over various stages of PIA, using PIAs tool support in the aforementioned case-study
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
