Infrastructure interdependence

Overview

Infrastructure interdependence is when different infrastructure sectors depend on another sector so that they function optimally (or at all). As the infrastructure sectors grow in complexity they became more intertwined leading to high dependence on one another. Highly dependent sectors are called tightly coupled sectors whereas decentralised sectors are labeled as loosely coupled sectors.

We must make the distinction between interdependence and dependent systems as the two are terms which are often used interchangeably. Dependency can be thought of as a series of straight lines from one element in a sector which underpins other elements in either the same sector or different sectors. Meanwhile interdependence can be thought of as a loop between sectors [1] where both systems depend on one another.

Take a look at the generic visualisations in the figures below to better understand the differences between dependent systems and interdependent systems.

Please note that multiple infrastructure elements make up an infrastructure system.

Why should we care about interdependence?

Infrastructure interdependence can cause issues when the climate changes (resulting in environmental alterations). In academia the interdependence types can be summarised in four classes [1]: Cyber, Physical, Geographic and Logical. See the graphic below for their respective definitions.

Although there are four different classes more than one class of interdependence can affect a pair, or more, of sectors. This means that the classes are not mutually exclusive. From a first glance the interdependence types might not seem intuitive especially the "logical" type however the figure below provides some examples of the different types.

Having interdependent critical infrastructure systems (CIS) could be disastrous in the face of damage to one system [3]. See the figure [4] below for a great visualisation of infrastructure system interdependence.

Can you think of any other reasons as to why interdependence causes brittleness in a system? How about any positives related to interdependence?

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References:

[1] Rinaldi, S. M., Peerenboom, J. P. and Kelly, T. K. (2001) ‘Identifying, understanding, and analyzing critical infrastructure interdependencies’, IEEE Control Systems Magazine. doi: 10.1109/37.969131.

[2] Geospatial information and technology association (2008) The Geospatial Dimensions of Critical Infrastructure and Emergency Response White Paper Series, Communications. Available at: https://cdn.ymaws.com/www.gita.org/resource/collection/36CCFB88-ED89-4FE3-9C35-8EB9D8120C95/InfrastructureInterdependencies.pdf.

[3] Farrell, A. E., Zerriffi, H. and Dowlatabadi, H. (2004) ‘ENERGY INFRASTRUCTURE AND SECURITY’, Annual Review of Environment and Resources. doi: 10.1146/annurev.energy.29.062403.102238.

[4] Little, R. G. (2003) ‘Toward more robust infrastructure: Observations on improving the resilience and reliability of critical systems’, in Proceedings of the 36th Annual Hawaii International Conference on System Sciences, HICSS 2003. doi: 10.1109/HICSS.2003.1173880.