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Interdependency is all the rage

We expect infrastructure services – energy, water, waste, transport and ICT – to be available whenever we need them. But future pressures such as population growth, increased demand and climate change mean that delivering systems capable of supporting national growth need a different approach. Research already provides an extensive evidence base on the effects of natural hazards and the knock-on impacts on individual utilities: however, today’s hot research topic is ‘infrastructure interdependencies’. Neil Carhart, Research Associate at the International Centre for Infrastructure Futures (ICIF), examines the rise of the term and why it is so important for identifying and preparing for the delivery of Britain’s future infrastructure needs.

The early years of the 21st Century have seen a significant increase in interest in infrastructure interdependency. By way of simple illustration the Ngram drawn from a search of Google’s scanned books from 1900 to 2008 show a sharp increase in the usage of the term after 1998.

It has been suggested that this increase stems from the 1995 Oklahoma City Bombing and the resultant Presidential Decision Directive 63 which stressed the importance of infrastructure interdependency in terms of the US’s national vulnerability. This influenced and set the tone for a body of work focusing on the emergent fragility arising from interdependency as distinct from potential emergent benefits.

An earlier version of the UK’s National Infrastructure Plan recognised this, noting that “opportunities to maximise infrastructure’s potential as a system of networks have not been exploited”. However, nor have they been completely neglected. Many different types of emergent opportunities have been recognised and documented.

Interdependencies can be created during the construction phase of a project to create economic and environmental efficiencies, as seen in the use of excavated material from Crossrail at Wallasea Island wetlands reserve and Mudchute Farm. This is an example of the output of one system becoming the input for another, an interdependency which could also be established during an infrastructure systems operational phase, using a circular economy model to improve resource resilience.

A report by Frontier Economics outlines further examples of the positive consequences of interdependency. One such case is the ElecLink Channel Tunnel Interconnector which proposes to install an electricity interconnector between the UK and France through the Channel Tunnel. This would intentionally create a spatial interdependency between an energy distribution asset and what was originally conceived and operated as a transport infrastructure asset. The initial estimates for installing the necessary cables along the Channel Tunnel were in the region of £216 million, compared to £280 million for laying them along the sea bed. The same physical asset has therefore been adapted to facilitate multiple transport and energy services. The services themselves remain functionally independent in an active sense (i.e. the rail link does not depend on the electricity distribution cables to function and vice versa) creating benefits in installation and operation, though that does not mean that the two cannot disrupt each other. New hazards will also be created and need to be managed.

Furthermore, as end users of infrastructure services, many of the things we value arise as the emergent properties of multiple interacting infrastructure assets. This can be something as simple as the ability to heat water and make a cup of coffee. To fully understand the value of infrastructure to society, and how infrastructure can adapt to meet changing needs and values, we must also understand infrastructure relationships.

An appreciation for the interdependencies between infrastructure assets, the services they facilitate and the governance mechanisms through which they are designed, delivered and operated can result in whole infrastructure systems which are more adaptable to the changing needs, values and requirements of the society and environment within which they sit. This requires the minimisation of vulnerabilities but also the optimisation of the benefits which interdependencies can create. In reality the two often exist simultaneously, with the same interdependency influencing both opportunities and unwanted risks.

It is essential that we continue the discussion about the nature of infrastructure interdependencies and the opportunities that emerge from them, as well as the vulnerabilities. These discussions will help us to create a robust shared-framework through which to better manage them to our advantage be it reducing fragility or increasing adaptability.

In a previous blog Roger Street described the cascading effects of extreme weather through interconnected infrastructure systems, and how failure of one system can impact on the recovery of another. The hazards posed by infrastructure interdependencies are clear and the importance of understanding and managing them should not be in doubt.

Roger also articulated the challenges in addressing this in practice. The situation can be very complex, not necessarily well understood, and requires the collaboration and co-operation of experts from across industry sectors. It is fortunate then that groups such as ARCC, the Infrastructure Transition Research Consortium, ICIF and iBUILD are making progress in understanding and addressing these challenges.

While there is rightly a focus on understanding and managing the failures and unwanted risks associated with infrastructure interdependencies, there is a complementary side. It is also possible to actively improve resilience, adaptability and efficiency through the purposeful identification, design and exploitation of interdependencies. Both hazards and benefits can emerge from the relationships within the infrastructure system.

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