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Urban infrastructures are essential to the health, safety, security and economic well-being of citizens and organisations. Therefore, the managers of critical infrastructures (CI) and infrastructure systems in urban areas need to be constantly aware of and prepared for to any man-made and natural disasters. In this paper, we propose a structured approach to assess extreme weather impacts on CI and discuss how resilience and risk tolerance of critical infrastructure can be enhanced. The approach is aimed at supporting CI owners' and managers' decision-making on a strategic level. It follows a process flow from hazard and CI identification, vulnerability analysis, potential damage estimation, loss assessment to identification and assessment of measures. The approach incorporates many elements, phases and methods from hazard assessment, vulnerability assessment, risk assessment and cost-benefit analysis (CBA), and combines and incorporates them into one aggregated structure, thus providing a holistic view to risk management and CI protection. The proposed approach is flexible in the sense that it encompasses not only a rigorous quantitative assessment, but also allows for a semi-quantitative or qualitative assessment. In addition, the approach enhances transparency of decision making and contributes to more comprehensive use of available information. The paper is based on research carried out in the INTACT and HARMONISE projects, which are co-funded by the European Union under the 7th Framework Programme. © 2016 WIT Press.

Extreme weather forms a major threat to electricity distribution networks and has caused many severe power outages in the past. A reliable electrical grid is something most of us take for granted, but storms, heavy snowfall, and other effects of extreme weather continue to cause disruptions in electricity supply. This paper contributes to ensuring the continuity of electricity supply under adverse weather events. The aim is to describe and to analyze how the continuity of electricity supply can be ensured in the case of extreme weather. Based on the research, the energy sector is highly dependent on the existing locations and structures of the current infrastructure. Aging infrastructure is commonly seen as a main vulnerability factor. The most vulnerable parts of the electricity distribution system to extreme weather conditions are the networks built as overhead lines. However, the resilience of the networks against extreme weather can be increased significantly in all phases of a disaster management cycle. Methods and technological solutions proposed in this paper to alleviate such problems include adjacent forest management and periodic aerial inspections, situational awareness, distributed generation and microgrids, placement of overhead lines, underground cabling, and unmanned air vehicles. However, it must be noticed that the methods and their value for stakeholders are context-dependent. Thus, their applicability and appropriateness may change over time.

Electricity networks in Finland are subject to adverse winter weather, particularly a combination of heavy snowfall with strong winds, causing electricity outages especially in the rural areas. The severe consequences of such events require that electricity distributors and the entire network of stakeholders establish a proactive risk management for achieving enhanced situational awareness during adverse weather events, efficient and effective recovering after electricity outage as well as improved preparedness against future events. This paper shows how a risk assessment performed with an Action Error Analysis (AEA) were conducted in order to enhance the resilience of electricity networks against adverse winter weather. This also encompassed an assessment of co-operation and communication structures about such risks. Adverse winter weather that took place in Pirkanmaa, in South-West Finland in November 2015, serves as a case study and laboratory for the assessments. The results of the AEA underscore the importance of co-operation and communication-related challenges that electricity distributors, rescue authorities and municipalities face in maintaining and obtaining a high level of resilience of electricity networks during and after heavy snowfalls. Against this background, novel ways and measures related to co-operation and communication of stakeholders to improve the resilience of electricity networks against future events are discussed.