Interdependent living

Dr Maryam Imani

As our weather becomes more extreme, the pressure on services to maintain energy, water and transport links increases. A research project at ARU is helping organisations plan for the future.

When critical services like energy, water and transport networks go down, it can cause a cascade of knock-on effects. Dr Maryam Imani and Dr Donya Hajializadeh have developed a tool that helps critical infrastructure operators to prepare for serious failures by working together.

In March 2013, at a time of year that normally marks the winter’s end, brutally cold weather pounded the UK in what became known as 'the big freeze'. West Scotland was particularly badly affected: drivers were trapped in deep snowdrifts for hours, while in Argyll, sheets of snow and ice damaged electricity pylons. Six thousand homes were left without power, heat, or light for almost a week.

Cold snaps, floods, landslides and severe storms have all become more common in recent years. When they hit, the companies on which we rely for vital services like energy, water and transport, need to be ready to minimise disruption and, if possible, keep their networks running.

Many do a good job. In 2013, Scottish and Southern Energy (SSE), which supplies Argyll’s electricity, had generators to ship to island communities that had lost power. Like other companies, it had prepared by modelling the impact that different hazards might have on its own infrastructure and customers.

But is that enough? Dr Maryam Imani, Senior Lecturer in Water Systems Engineering at Anglia Ruskin University, points out that when one service goes down, it can precipitate a 'cascade of failures' that affects other services too. No infrastructure network exists in a bubble; but the private companies who manage them, with different priorities and budget constraints, often prepare for critical incidents as if they do.

"Infrastructure providers are good at managing their own assets. The problems start when these connect up as interdependent networks."

Imagine, for example, that flooding closes a small, unclassified road. Not unreasonably, the local road maintenance firm may consider reopening it a low priority compared with busier routes. But if the closure also cuts off vital access to a water pumping station, or an electricity substation, thousands of people could be affected.

“Infrastructure providers are good at managing their own assets, like pipelines, roads, or power cables,” Maryam says. “The problems start when these connect up as interdependent networks.”

She believes that the Government needs to enable more joined-up planning between different utility services providers. But making the case for that can be tricky: “These companies know the problem exists, but because they all work independently using different systems, they cannot easily show how things would be different if they were working more closely together.”

Her latest research begins to address that problem. In 2016, Maryam and her colleague, Dr Donya Hajializadeh, received funding from the Natural Environment Research Council to run an eight month project including a case study with Argyll’s local service providers: Transport Scotland, Scottish Water, SSE and Atkins (a major engineering and design consulting firm). The aim was to give them a decision-making tool to help them plan co-operatively for their interdependent assets in critical incidents like the big freeze.

The researchers gathered information about each company, how they prioritise their assets, and what they do when systems fail. They then modelled the entire, interdependent network in the form of a digital map showing the connections between Argyll’s energy, water and transport networks.

Service providers can pick any asset on the map, such as a treatment plant, electricity pylon, or railway line, and model how the entire, interdependent network might be affected if it failed. They can also put a figure on how many people would be affected, and simulate how quickly different fixes would bring services back online – effectively helping them to measure the network’s overall resilience.

Because the research was a short pilot study, the decision support system is still a work in progress. Maryam hopes to refine it in a follow-up project, for which she is currently seeking funding. The project partners are, similarly, keen for the research to progress to the next stage

“All of the partners have been hugely enthusiastic,” Maryam adds. “They already had a sense of where the vulnerabilities in their network might be. The difference now is that, for the first time, they can measure and quantify failure propagation across the network and its resilience, rather than relying on gut feeling.”

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