The importance of resistance in the context of critical infrastructure resilience: An extension of the CIERA method
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Ministerstvo Vnitra České Republiky, (VK01030014)
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Citation: Rehak, D.; Flynnova, L.; Hromada, M.; Fuggini, C. The Importance of Resistance in the Context of Critical Infrastructure Resilience: An Extension of the CIERA Method. Systems 2023,11, 506. https:// doi.org/10.3390/systems11100506 Academic Editors: Randy Buchanan and Gregory S. Parnell Received: 3 September 2023 Revised: 27 September 2023 Accepted: 29 September 2023 Published: 8 October 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). systems Article The Importance of Resistance in the Context of Critical Infrastructure Resilience: An Extension of the CIERA Method David Rehak 1,* , Lucie Flynnova 1, Martin Hromada 2and Clemente Fuggini 3 1Faculty of Safety Engineering, VSB—Technical University of Ostrava, 700 30 Ostrava, Czech Republic; [email protected] 2 Faculty of Applied Informatics, Tomas Bata University in Zlin, 760 05 Zlin, Czech Republic; hr[email protected] 3Rina Consulting S.p.A., 20123 Milano, Italy; [email protected] *Correspondence: david.r[email protected]; Tel.: +420-597-322-816 Abstract: Technical sectors compose an inseparable and elementary part of a complex critical infrastructure (CI) system. Their provided services are essential to the functioning of all of the dependent sectors of CI on which society and states depend, especially in areas experiencing high levels of urbanisation. The initial point for effective CI elements’ protection is the permanent assessment and strengthening of their capacity for resilience to the negative effects of internal and external threats. The current perceptions of resilience focus primarily on repressive components responsive to incidents (i.e., robustness, recoverability, and adaptability), while minimal attention is paid to the preventative components. The article’s contribution to this literature gap is its definition of resistance, which can be considered as a CI element’s ability to prevent the occurrence of incidents. To this goal, the current study defines (1) the individual factors (variables and parameters) determining CI resistance and (2) the methodological procedure for infrastructure element resistance assessment in order to identify the weak points throughout a complex CI system and subsequently strengthen them. Moreover, a practical example of resistance assessment for a selected critical energy infrastructure element is presented. The main outcome of this article is the definition of the primary steps for the expansion of the CIERA method, via the enhancement of CI components’ resilience capacity in the prevention phase. Keywords: resistance; physical resistance; crisis preparedness; anticipation ability; security measures; critical infrastructure resilience 1. Introduction The term resilience was firstly introduced by Holling [ 1 ] in 1973 within an ecology context as “a measure of the persistence of systems and of their ability to absorb change and disturbance and still maintain the same relationships between populations or state variables”, and was originally proposed as a formulation for systems which can be characterized as ecological. However, the concept of resilience has started to be reflected over time in other scientific areas, too, such as psychology, economics, and sociology. It was, therefore, a reasonable consequence that resilience as a concept would be recognized for its feasibility and added value in technically oriented social fields as well. CI resilience was firstly defined in 2009 in the Critical Infrastructure Resilience Final Report and Recommendations [ 2 ], and within this context, is perceived as “the ability to absorb, adapt to, and/or rapidly recover from a potentially disruptive event”. Based on this definition, three key components (i.e., robustness, recoverability, and adaptability) have been identified in [ 2 ] in order to determine resilience. Although these components are key determinants of resilience, a more thorough investigation reveals that they only have a responsive character, as their impact on CI resilience is only apparent at the time of the incident [ 2 ]. This observation leads to the assumption that there is no preventative Systems 2023,11, 506. https://doi.org/10.3390/systems11100506 https://www.mdpi.com/journal/systems
Systems 2023,11, 506 2 of 15 component in the process of resilience building; therefore, this role could be supported by resistance, which can be perceived as the CI ability to prevent the incident occurring. The Britannica Dictionary [ 3 ] defines resistance as the ability to prevent something from having an effect. The term resistance is used by authors within various and broader scientific fields, e.g., in medicine, to refer to antibacterial resistance to antibiotics [ 4 , 5 ], or in sociology to refer to the manifestation of social resistance [ 6 , 7 ]. The adaptation and integration of the resistance concept into engineering practice were influenced by the ecology field, where the term was firstly introduced in relation to resilience by Sugden [ 8 ] and in connection with alpine lake ecosystems. The author defined the main logical differences between resistance and resilience. He sees resistance as a measure of how much an ecosystem is able to withstand a disturbance such as the introduction of an alien species. Resilience was then considered as a response and recovery measure of the ecosystem after eliminating the source of the change. Over the last decade, CI resilience issues have been analysed by several authors. Some studies deal more generally with the importance of resistance in the context of CI resilience [ 9 – 12 ], while other publications have already defined the preventive factors of resilience and point to the necessity of their separation from robustness [ 13 – 16 ]. However, there are several frameworks which have already defined and evaluated the resistance variables when assessing the level of CI resilience [ 17 – 19 ]. Under this scope, resistance can be perceived as an important component of resilience, which should be defined and determined through basic factors. Regarding the above presented landscape, the added value of this article is to define CI resistance and to describe its integration and implementation within the established CIERA method [ 20 ]. The most crucial part of this article includes the expression of individual CI resistance factors and the methodological procedure for their assessment with the ambition to strengthen the resistance of these CI systems. Therefore, this study contributes significantly to the definition of a comprehensive concept for CI systems resilience. 2. Materials and Methods The current study attempts to prove the suitability of integrating resistance into resilience, hence the definition of resilience and its meaning for a CI system are required in the initial phase. The origin of the word resilience is rooted in the Latin language, and it is found as resiliere, which literally translates as bounce back [ 21 ]. Resilience within the context of CI firstly appeared in 2009 [ 2 ], but this definition was expanded in 2012 by the US National Academies of Science in order to include preparation and planning and was expressed as “the system’s ability to prepare and plan for, absorb, recover from, and successfully adapt to disruptive events” [ 22 ]. Since then, there has been no essential change in the perception of CI resilience, which is also illustrated by the definitions of CI resilience given in several important publications within this period [ 11 , 23 – 29 ]. All of the definitions found in these studies are oriented towards the so-called technical resilience, which refers to critical infrastructure elements (CIEs) and is expressed by their absorption capacity and their ability to recover and adapt to incidents that have occurred. However, a slight shift in the consideration of CI system resilience occurred in 2022, when the European Union issued a respective Directive which has focused on the resilience of critical entities [ 30 ]. Resilience within this context is considered as “a critical entity’s ability to prevent, protect against, respond to, resist, mitigate, absorb, accommodate and recover from an incident”. This definition is evidently spotlighting and promoting the organisational resilience, aiming at increasing the resilience of the entities which are responsible for these CIEs [31]. From the summary and collection of the above-mentioned definitions, it can be stated that CI resilience consists of four phases, which together form the so-called CI resilience cycle [ 32 ] and its significance is the ever-increasing CIE protection. Even though resilience is enhanced especially in the adaptation phase to an incident that has occurred, the increase in resilience can be noticed even from the recovery phase in some cases (e.g., by adopting and installing a completely new and more resilient technology).
Systems 2023,11, 506 3 of 15 The initial phase of the CI resilience cycle is prevention, and its importance lies in preventing the occurrence of an incident because of its potential threat or impact on a CIE. These measures aim at the early detection of an incident and the element’s preparedness for its impact. When an incident occurs, then the resilience cycle moves into the absorption phase. The essence of this phase is to absorb the incident’s effects on the CIE. The element’s ability to absorb the incident’s effects is referred to as robustness. After the completion of the incident, resilience moves into the recovery phase. The significance of this phase is to mitigate the consequences of the incident’s impact on the CIE and restore its performance to its initial level. Adaptation is the final stage of the CI resilience cycle and refers to the importance of the CIE’s adaptation to the occurred incident, strengthening thereby the element’s overall resilience capacity. CI resilience is currently determined by three components, as also mentioned in the introduction, but these characterise only three of the above phases (i.e., absorption, recovery, and adaptation), since the prevention phase is not yet considered among the components. However, and before moving to the definition of the component in the prevention phase, it is appropriate to present the components in the existing three phases of resilience [2]: • robustness is “the ability of the system to absorb the effects of a disruption without significant deviation from normal operating performance”; •recoverability is “the ability of the system to recover quickly from potentially disruptive events”; • adaptability is “the ability of the system to adapt to a shock to normal operating conditions”. Research on these three specific components has been conducted in the past by a number of reputable authors [ 32 – 39 ]. After a detailed analysis of these publications, variables determining the CIE resilience components were defined (Figure 1) as part of the CIERA method’s development [20]. Systems2023,11,xFORPEERREVIEW3of15 increaseinresiliencecanbenoticedevenfromtherecoveryphaseinsomecases(e.g.,by adoptingandinstallingacompletelynewandmoreresilienttechnology). TheinitialphaseoftheCIresiliencecycleisprevention,anditsimportanceliesin preventingtheoccurrenceofanincidentbecauseofitspotentialthreatorimpactonaCIE. Thesemeasuresaimattheearlydetectionofanincidentandtheelement’spreparedness foritsimpact.Whenanincidentoccurs,thentheresiliencecyclemovesintotheabsorption phase.Theessenceofthisphaseistoabsorbtheincident’seffectsontheCIE.Theelementʹs abilitytoabsorbtheincidentʹseffectsisreferredtoasrobustness.Afterthecompletionof theincident,resiliencemovesintotherecoveryphase.Thesignificanceofthisphaseisto mitigatetheconsequencesoftheincident’simpactontheCIEandrestoreitsperformance toitsinitiallevel.AdaptationisthefinalstageoftheCIresiliencecycleandreferstothe importanceoftheCIEʹsadaptationtotheoccurredincident,strengtheningtherebythe element’soverallresiliencecapacity. CIresilienceiscurrentlydeterminedbythreecomponents,asalsomentionedinthe introduction,butthesecharacteriseonlythreeoftheabovephases(i.e.,absorption,recovery,andadaptation),sincethepreventionphaseisnotyetconsideredamongthecomponents.However,andbeforemovingtothedefinitionofthecomponentintheprevention phase,itisappropriatetopresentthecomponentsintheexistingthreephasesofresilience [2]: robustnessis“theabilityofthesystemtoabsorbtheeffectsofadisruptionwithoutsignificantdeviationfromnormaloperatingperformance”; recoverabilityis“theabilityofthesystemtorecoverquicklyfrompotentiallydisruptive events”; adaptabilityis“theabilityofthesystemtoadapttoashocktonormaloperatingconditions”. Researchonthesethreespecificcomponentshasbeenconductedinthepastbya numberofreputableauthors[32–39].Afteradetailedanalysisofthesepublications,variablesdeterminingtheCIEresiliencecomponentsweredefined(Figure1)aspartofthe CIERAmethod’sdevelopment[20]. Figure1.VariablesdeterminingCIEresiliencecomponents[20]. Figure 1. Variables determining CIE resilience components [20]. Based on the above, it can be concluded that there is currently no characteristic component to express the first resilience phase (i.e., prevention). This component could be considered the resistance, which in the context of ecology (from which the whole resilience concept initiated) is found as the ability of an ecosystem to protect itself against a perturbation [8].
Systems 2023,11, 506 4 of 15 3. Results The following text is a key part of the article, as the authors present here the results of their original research. These results refer mainly to the definitions of (1) CI resistance, (2) the factors determining this resistance, and (3) a methodological procedure for assessing these factors in order to strengthen CIE resistance. The term resistance was coined by Leonardo da Vinci in The Madrid Codices I–II [ 40 ] in order to describe the resistance of water and air to moving solid bodies, as well as of water and fire moving in air. An important definition of resistance was elaborated from Georg Ohm later, in 1827, and it was in relation to the difficulty of passing an electric current through a substance [ 41 ]. Another use of the term resistance was recorded in 1862, in the sense of organised opposition to an invader [ 42 ]. In the following period, the term was increasingly used in a military-political context to refer to underground resistance movements in any country. Over time, the term resistance has been inserted into the vocabulary and practice of various other scientific fields, such as medicine (e.g., antibiotic or antimicrobial resistance, immune resistance, psychological resistance), ecology (e.g., ecological or environmental resistance, pesticide resistance) or economics (e.g., resistance economy). In the context of the current study, which is CI systemic resilience, the term resistance has not yet been defined. Some authors consider resistance and resilience as two distinct concepts [ 43 ], understanding resistance as being similar to preventing or protecting, while resilience as akin to responding or recovering. Other authors include the two terms in the same context but consider resistance as a component of resilience responsible for reducing the severity or consequences of a hazard [ 33 ]. In both cases, it can be stated that this interpretation is inaccurate, as resistance in all of the above mentioned fields is a factor preventing the emergence of an incident. It is thus a fundamental component of resilience that has a clearly preventative but not mitigating character. Taking into account these considerations, the authors of this article have created a definition where they view resistance as “the critical infrastructure ability to prevent the occurrence of an incident”. In this context, it is appropriate to draw attention to the fact that this capacity of resistance minimizes the transmission of the incident consequences to dependent CI sectors, thereby preventing the occurrence of cascading and synergistic effects [ 44 ]. Based on the above, it is feasible to define resistance within the CI resilience context and, as a consequence, this resistance is to be seen as one of the essential resilience components, especially in its initial phase. Other resilience components are robustness, recoverability, and adaptability. The authors’ perceptions of these components regarding an incident are presented in Figure 2. In the following part of the article and with reference to Figure 1, the definition of the variables determining CIE resistance is feasible (Figure 3). It is evident from the above definition of resistance that the significance of these variables must be their ability to prevent incidents. For this scope, all of these variables must be of a preventative character. The default variable is crisis preparedness. The essence of crisis preparedness is to increase the readiness of CI entities and their infrastructures against disasters [ 45 ]. This preparedness consists in a thorough assessment of risks and the subsequent processing of security planning documentation. Risk assessment is considered a systematic and effective way of identifying, analysing, and evaluating risks and determining the most effective costs and means to minimize these risks [ 46 ]. For this purpose, it is advisable to use the recommended risk assessment techniques [ 47 ]. Security planning documentation specifically includes emergency plans and a CI entity’s crisis preparedness plan [ 48 ]. An emergency plan is a document containing a comprehensive set of preventive measures aimed at preparing the CI entity for an accident or other incident, including natural and man-made threats. For example, in the Czech Republic, the crisis preparedness plan serves CI entities to ensure their own functioning during disasters [49].
Systems 2023,11, 506 5 of 15 Systems2023,11,xFORPEERREVIEW5of15 Figure2.ResistanceperceptionsinrelationtoCIresilience. InthefollowingpartofthearticleandwithreferencetoFigure1,thedefinitionofthe variablesdeterminingCIEresistanceisfeasible(Figure3).Itisevidentfromtheabove definitionofresistancethatthesignificanceofthesevariablesmustbetheirabilitytopreventincidents.Forthisscope,allofthesevariablesmustbeofapreventativecharacter. Figure3.DefiningvariablesdeterminingtheCIE’sresistance. Thedefaultvariableiscrisispreparedness.Theessenceofcrisispreparednessisto increasethereadinessofCIentitiesandtheirinfrastructuresagainstdisasters[45].This preparednessconsistsinathoroughassessmentofrisksandthesubsequentprocessingof securityplanningdocumentation.Riskassessmentisconsideredasystematicandeffectivewayofidentifying,analysing,andevaluatingrisksanddeterminingthemosteffective costsandmeanstominimizetheserisks[46].Forthispurpose,itisadvisabletousethe recommendedriskassessmenttechniques[47].SecurityplanningdocumentationspecificallyincludesemergencyplansandaCIentity’scrisispreparednessplan[48].Anemergencyplanisadocumentcontainingacomprehensivesetofpreventivemeasuresaimed atpreparingtheCIentityforanaccidentorotherincident,includingnaturalandmanmadethreats.Forexample,intheCzechRepublic,thecrisispreparednessplanservesCI entitiestoensuretheirownfunctioningduringdisasters[49]. Thesecondvariableisanticipationability.Thesubstanceofthisvariableistheability oftheCIentitytopredictthepossibleincidentemergenceasaresultofthethreatimpact. ThesearebasicallytheactivitiesoftheentityinthecontextofdefiningtheriskenvironmentthataffectstheCIE[33].Forthispurpose,itispossibletouseoneoftheavailable Figure 2. Resistance perceptions in relation to CI resilience. Systems2023,11,xFORPEERREVIEW5of15 Figure2.ResistanceperceptionsinrelationtoCIresilience. InthefollowingpartofthearticleandwithreferencetoFigure1,thedefinitionofthe variablesdeterminingCIEresistanceisfeasible(Figure3).Itisevidentfromtheabove definitionofresistancethatthesignificanceofthesevariablesmustbetheirabilitytopreventincidents.Forthisscope,allofthesevariablesmustbeofapreventativecharacter. Figure3.DefiningvariablesdeterminingtheCIE’sresistance. Thedefaultvariableiscrisispreparedness.Theessenceofcrisispreparednessisto increasethereadinessofCIentitiesandtheirinfrastructuresagainstdisasters[45].This preparednessconsistsinathoroughassessmentofrisksandthesubsequentprocessingof securityplanningdocumentation.Riskassessmentisconsideredasystematicandeffectivewayofidentifying,analysing,andevaluatingrisksanddeterminingthemosteffective costsandmeanstominimizetheserisks[46].Forthispurpose,itisadvisabletousethe recommendedriskassessmenttechniques[47].SecurityplanningdocumentationspecificallyincludesemergencyplansandaCIentity’scrisispreparednessplan[48].Anemergencyplanisadocumentcontainingacomprehensivesetofpreventivemeasuresaimed atpreparingtheCIentityforanaccidentorotherincident,includingnaturalandmanmadethreats.Forexample,intheCzechRepublic,thecrisispreparednessplanservesCI entitiestoensuretheirownfunctioningduringdisasters[49]. Thesecondvariableisanticipationability.Thesubstanceofthisvariableistheability oftheCIentitytopredictthepossibleincidentemergenceasaresultofthethreatimpact. ThesearebasicallytheactivitiesoftheentityinthecontextofdefiningtheriskenvironmentthataffectstheCIE[33].Forthispurpose,itispossibletouseoneoftheavailable Figure 3. Defining variables determining the CIE’s resistance. The second variable is anticipation ability. The substance of this variable is the ability of the CI entity to predict the possible incident emergence as a result of the threat impact. These are basically the activities of the entity in the context of defining the risk environment that affects the CIE [ 33 ]. For this purpose, it is possible to use one of the available methods aimed at indicating the disruption of CIE resilience [ 29 , 50 , 51 ]. On the basis of the possible element resilience disruption assessment, preventive measures are implemented to prevent the emergence of an incident. Other measures which can be used to predict the emergence of incidents are audits or software applications that enable incident prediction [52,53]. The third variable is physical resistance. The substance of this variable is the CIE’s ability to resist the effects of natural and man-made threats (e.g., rockslide or truck attack), through the material and structural resistance of CI buildings [ 54 ]. The core areas of physical resistance are fire, seismic and explosion resistance. Fire resistance is the ability of building structures to withstand the effects of a fully developed fire, without their loadbearing capacity and stability, integrity and insulating ability being particularly affected [ 55 ]. Seismic resistance is the ability of building structures to withstand the effects of earthquakes through sufficient elasticity or ductility [ 56 ]. Explosion resistance is the ability of buildings to prevent explosions (i.e., active explosion protection) or to eliminate the effects of an explosion (i.e., passive explosion protection) through their layout and measures [57].
Systems 2023,11, 506 6 of 15 The last variable is security measures. The usefulness of these measures is in the monitoring and physical protection of CIEs. The goal of monitoring is mainly to check the technical condition of the elements, their functions and the services they provide [ 58 ]. If any deficiencies are identified through monitoring, it is advisable to start the process of repairing or modernizing these elements. The essence of modernization is especially in maintaining the technical state of elements with current trends and technologies [ 59 ]. A suitable preventive tool for CIE protection is also a physical protection system, which is determined by regime, organizational and technical measures [60]. A comprehensive overview of the variables and their parameters describing CIE resilience is presented graphically in Figure 4. The structure of this figure is designed in the form of a descending classification, where the first level consists of variables, the second level consists of parameters, and the third level recommends some potentially suitable criteria. Systems2023,11,xFORPEERREVIEW6of15 methodsaimedatindicatingthedisruptionofCIEresilience[29,50,51].Onthebasisofthe possibleelementresiliencedisruptionassessment,preventivemeasuresareimplemented topreventtheemergenceofanincident.Othermeasureswhichcanbeusedtopredictthe emergenceofincidentsareauditsorsoftwareapplicationsthatenableincidentprediction [52,53]. Thethirdvariableisphysicalresistance.ThesubstanceofthisvariableistheCIE’s abilitytoresisttheeffectsofnaturalandman-madethreats(e.g.,rockslideortruckattack), throughthematerialandstructuralresistanceofCIbuildings[54].Thecoreareasofphysicalresistancearefire,seismicandexplosionresistance.Fireresistanceistheabilityof buildingstructurestowithstandtheeffectsofafullydevelopedfire,withouttheirloadbearingcapacityandstability,integrityandinsulatingabilitybeingparticularlyaffected [55].Seismicresistanceistheabilityofbuildingstructurestowithstandtheeffectsofearthquakesthroughsufficientelasticityorductility[56].Explosionresistanceistheabilityof buildingstopreventexplosions(i.e.,activeexplosionprotection)ortoeliminatetheeffects ofanexplosion(i.e.,passiveexplosionprotection)throughtheirlayoutandmeasures[57]. Thelastvariableissecuritymeasures.TheusefulnessofthesemeasuresisinthemonitoringandphysicalprotectionofCIEs.Thegoalofmonitoringismainlytocheckthe technicalconditionoftheelements,theirfunctionsandtheservicestheyprovide[58].If anydeficienciesareidentifiedthroughmonitoring,itisadvisabletostarttheprocessof repairingormodernizingtheseelements.Theessenceofmodernizationisespeciallyin maintainingthetechnicalstateofelementswithcurrenttrendsandtechnologies[59].A suitablepreventivetoolforCIEprotectionisalsoaphysicalprotectionsystem,whichis determinedbyregime,organizationalandtechnicalmeasures[60]. AcomprehensiveoverviewofthevariablesandtheirparametersdescribingCIEresilienceispresentedgraphicallyinFigure4.Thestructureofthisfigureisdesignedinthe formofadescendingclassification,wherethefirstlevelconsistsofvariables,thesecond levelconsistsofparameters,andthethirdlevelrecommendssomepotentiallysuitable criteria. Figure4.VariablesandtheirparametersdescribingtheCIEʹsresistance. Theabove-definedvariablesandtheirparameterscanbeusedinparticulartoassess CIEresistance,e.g.,throughtheassessmentmechanismofthesemi-quantitativeCIERA method[20].Thismethodissuitableforassessingtheresilienceofelementsintechnical Figure 4. Variables and their parameters describing the CIE’s resistance. The above-defined variables and their parameters can be used in particular to assess CIE resistance, e.g., through the assessment mechanism of the semi-quantitative CIERA method [ 20 ]. This method is suitable for assessing the resilience of elements in technical infrastructures, such as energy, transport, communication and information systems or water management. For this purpose, it is necessary to assess all parameters that determine each variable. These parameters must be evaluated against the specific threat, as the level of resistance of the elements cannot be generalised. The assessment can be carried out, similarly to the CIERA method, through point evaluation, where 5 points is the best and 1 point the worst. The level of each resistance variable is then calculated by a weighted average of the individual parameters (see Equation (1)). Because the parameter level is represented as a score between 1 and 5, the resulting value must be multiplied by 20, which gives a result expressed as a percentage. Vr=20 t ∑ s=1 Psws(1) where Vr = the r-th CIE resistance variable [%]; Ps = the s-th CIE resistance parameter [points]; ws = the s-th standardised weight of the s-th CIE resistance parameter in the interval h0;1i ; t = the number of parameters in the r-th variable. The standardised weights
Systems 2023,11, 506 7 of 15 of the parameters were determined using the pairwise comparison method [ 61 ] and are presented in Table 1. Table 1. Standardised weights for parameters determining resistance variables of CIEs. Variables Parameters and Their Standardised Weights ∑ Crisis preparedness (V1)Risk assessment (P1.1) Safety planning (P1.2)- w1.1 = 0.4 w1.2 = 0.6 - w1= 1.0 Anticipation ability (V2) Disruption indicating procedure of CIE resilience (P2.1) Regular checks and surveys (P2.2)Software applications for incident prediction (P2.3) w2.1 = 0.4 w2.2 = 0.3 w2.3 = 0.3 w2= 1.0 Physical resistance (V3)Fire resistance (P3.1) Seismic resistance (P3.2) Explosion resistance (P3.3) w3.1 = 0.4 w3.2 = 0.3 w3.3 = 0.3 w3= 1.0 Security measures (V4)Monitoring (P4.1)Physical protection system (P4.2)- w4.1 = 0.4 w4.2 = 0.6 - w4= 1.0 In this context, it is worth noting that the current way of calculating individual variables does not take into account the changing nature of a CI element, i.e., whether it is a point, areal or line element [ 62 , 63 ]. The resulting level of CIE resistance is expressed by the weighted average of the individual variables (see Equation (2)): R= t ∑ r=1 Vrhr(2) where R = the CIE resistance [%]; Vr = the r-th variable of CIE resistance [%]; hr = the r-th standardised weight of the r-th variable of CIE resistance [ h0;1i ]; t = the number of variables expressing the CIE resistance. The standardised weights of the variables were expressed using the pairwise comparison method [61] and are presented in Table 2. Table 2. Standardised weights for variables determining the resistance of CIEs. Variables Standardised Weights Crisis preparedness (V1)h1= 0.2 Anticipation ability (V2)h2= 0.25 Physical resistance (V3)h3= 0.25 Security measures (V4)h4= 0.3 ∑1.00 A potential graphical representation of the resulting level of CIE resistance and its variables is presented in Figure 5. The resulting level of CIE resistance is expressed as a percentage, which in itself provides only a rough idea of the protection of the element. A more detailed evaluation of this level is necessary by classifying it according to the reference scale (Table 3) which is based on the CIERA method [20].
Systems 2023,11, 506 8 of 15 Systems2023,11,xFORPEERREVIEW8of15 ApotentialgraphicalrepresentationoftheresultinglevelofCIEresistanceandits variablesispresentedinFigure5. Figure5.ExpressionofCIEresistancelevels. TheresultinglevelofCIEresistanceisexpressedasapercentage,whichinitselfprovidesonlyaroughideaoftheprotectionoftheelement.Amoredetailedevaluationof thislevelisnecessarybyclassifyingitaccordingtothereferencescale(Table3)whichis basedontheCIERAmethod[20]. Table3.ReferencescaleforassessingtheCIEresistancelevel[20]. ResistanceLevelsofCriticalInfrastructureElements Highlevelofresistance85–100% Acceptablelevelofresistance69–84% Lowlevelofresistance53–68% Insufficientlevelofresistance37–52% Criticallevelofresistance≤36% Theacceptabilityofresistanceisdiversifiedintofiveratinglevels,anditisdrivenby theincreaseddesire,intheinterestoftheusers,toexaminethecompositionofresistance inmoredetail(i.e.,toretrospectivelybreakdownresistanceintoindividualvariablesand parameters).Ifresistancereachesalevelof≤68%,identificationofweaknessesconsisting inabreakdownoftheresistanceassessmentresultsshouldbecarriedoutatthelevelof theparametersconcerned.Forparametersscoring2orless,itisnecessarytoreviewthe affectedareaoftheassessedelementandstarttheprocessofstrengtheningitsresistance. Tostrengthentheresilienceoftheseparameters,itissuitabletouse,forexample,the toolsforstrengtheningCIEresilience[64].Thesetoolsshouldbeappropriatelyimplementedtostrengthenelementresistancethroughtherelevantvariables.Ingeneral,itis feasibletodividethesetoolsintoexternalandinternaltoolsand,duetotheirnature,into thematicgroups.Insomecases,thesearetoolsregulatingprocessandfunctionalareasof organizationmanagement(i.e.,personnel,financialandprocesstools).Incontrary,the toolsarefocusedonexternalfactors(principleofthePESTLEmethod),consideringpolitical,economic,social,legislative,technological,andenvironmentalaspects.Toolssuitable forstrengtheningresistancevariablesarepresentedinFigure6. Figure 5. Expression of CIE resistance levels. Table 3. Reference scale for assessing the CIE resistance level [20]. Resistance Levels of Critical Infrastructure Elements High level of resistance 85–100% Acceptable level of resistance 69–84% Low level of resistance 53–68% Insufficient level of resistance 37–52% Critical level of resistance ≤36% The acceptability of resistance is diversified into five rating levels, and it is driven by the increased desire, in the interest of the users, to examine the composition of resistance in more detail (i.e., to retrospectively break down resistance into individual variables and parameters). If resistance reaches a level of ≤68%, identification of weaknesses consisting in a breakdown of the resistance assessment results should be carried out at the level of the parameters concerned. For parameters scoring 2 or less, it is necessary to review the affected area of the assessed element and start the process of strengthening its resistance. To strengthen the resilience of these parameters, it is suitable to use, for example, the tools for strengthening CIE resilience [ 64 ]. These tools should be appropriately implemented to strengthen element resistance through the relevant variables. In general, it is feasible to divide these tools into external and internal tools and, due to their nature, into thematic groups. In some cases, these are tools regulating process and functional areas of organization management (i.e., personnel, financial and process tools). In contrary, the tools are focused on external factors (principle of the PESTLE method), considering political, economic, social, legislative, technological, and environmental aspects. Tools suitable for strengthening resistance variables are presented in Figure 6.
Systems 2023,11, 506 9 of 15 Systems2023,11,xFORPEERREVIEW9of15 Figure6.ToolssuitableforstrengtheningCIEresiliencevariables[64]. 4.PracticalExampleofResistanceAssessmentforaSelectedEnergyCIE Finally,itisappropriatetodemonstratetheapplicabilityoftheresultsobtainedin thecurrentstudybytheirimplementationtoaselectedenergyCIE.Theselectedelement isanelectricalstationofatransmissionsystemwhichisaEuropeanCIE.IntheCzech Republic,thereareatotalof33electricalstationsinoperationinthetransmissionsystem, ofwhichfourstationsensuretheconnectionbetweenthe400kVand220kVsystems,32 stationsensuretheconnectionbetweenTSandDS,10stationsensuretheoutputofpower frompowerplants,andeightstationsarecomposedof400kVand220kVsubstations. Theassessedelectricalstationisanonymizedforsecurityreasons,andonlyitsbasicdescriptionisprovidedinTable4. Table4.DescriptionofselectedenergyCIE. ElementnameTransmissionsystemelectricalstation Sector/subsectorEnergy/Electricity/Transmission Keytechnologies 1.Transformers 2.Voltageinstrumenttransformers 3.Currentinstrumenttransformers 4.Compensationchokes 5.Disconnectorsandgroundingswitches 6.Busbarsandbranches 7.Circuitbreakers Elementperformance400/220kV Figure 6. Tools suitable for strengthening CIE resilience variables [64]. 4. Practical Example of Resistance Assessment for a Selected Energy CIE Finally, it is appropriate to demonstrate the applicability of the results obtained in the current study by their implementation to a selected energy CIE. The selected element is an electrical station of a transmission system which is a European CIE. In the Czech Republic, there are a total of 33 electrical stations in operation in the transmission system, of which four stations ensure the connection between the 400 kV and 220 kV systems, 32 stations ensure the connection between TS and DS, 10 stations ensure the output of power from power plants, and eight stations are composed of 400 kV and 220 kV substations. The assessed electrical station is anonymized for security reasons, and only its basic description is provided in Table 4. In the subsequent section, a semi-quantitative assessment of this selected element’s resistance to the selected threat is conducted and presented. This threat is a terrorist attack using an explosive device aimed at physical damage to the control workplace and causing a widespread blackout. The assessment of the resistance of the selected energy CIE is realised in three steps: •Step 1: Analysis and scoring of each parameter; •Step 2: Calculation of the level of each variable; •Step 3: Determination of the resulting energy CIE resistance level. Step 1: The results of the analysis, including the point rating and its rationale for individual parameters determining the element resistance, are shown in Table 5.