The Holistic Integrity Test (HIT) - quantified resilience analysis
1 Ove Arup & Partners, 6th Floor, 3 Piccadilly Place, Manchester, M1 3BN, UK
2 J B Chatterton & Associates, 32 Windermere Road, Moseley, Birmingham, B13 9JP
The Holistic Integrity Test (HIT) - Quantified Resilience Analysis. Rising sea levels and wider climate change mean we face an increasing risk from flooding and other natural hazards. Tough economic times make it difficult to economically justify or afford the desired level of engineered risk reduction. Add to this significant uncertainty from a range of future predictions, constantly updated with new science. We therefore need to understand not just how to reduce the risk, but what could happen should above design standard events occur. In flood terms this includes not only the direct impacts (damage and loss of life), but the wider cascade impacts to infrastructure systems and the longer term impacts on the economy and society. However, understanding the “what if” is only the first part of the equation; a range of improvement measures to mitigate such effects need to be identified and implemented. These measures should consider reducing the risk, lessening the consequences, aiding the response, and speeding up the recovery. However, they need to be objectively assessed through quantitative analysis, which underpins them technically and economically. Without such analysis, it cannot be predicted how measures will perform if the extreme events occur. It is also vital to consider all possible hazards as measures for one hazard may hinder the response to another. The Holistic Integrity Test (HIT), uses quantitative system analysis and “HITs” the site, its infrastructure, contained dangers and wider regional system to determine how it copes with a range of severe shock events, Before, During and After the event, whilst also accounting for uncertainty (as illustrated in figure 1). First explained at the TINCE 2014 Nuclear Conference in Paris, it was explained in terms of a Nuclear Facility needing to analyse the site in response to post Fukushima needs; the hit is however universally applicable. The HIT has three key risk reduction goals: The ability to tolerate and withstand shocks, while continuing to sustain key safety functions; the ability to wisely direct and manage the crisis situation, accounting for the diverse scenarios that could occur; to be able to quickly recovery and stabilise to a safe and secure state that is stable and sustainable in the long term.
© The Authors, published by EDP Sciences, 2016
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