Infrastructure interdependencies: Opportunities from complexity

In the lead up to CIRIA's Infrastructure interdependence in practice event (the third event in the infrastructure and resilience series) which takes place in London on March 21, Dr Darren Grafius, a research fellow with Cranfield University’s Complex Systems Research Centre, explores how interdependency can be seen positively and exploited to build resilience and sustainability in today’s global infrastructure systems.

Interdependencies in infrastructure systems are primarily focused on for the vulnerabilities they represent to system stability. However, they also represent opportunities for ways in which systems can become more resilient, sustainable, and effective at delivering their intended services as well as generating entirely novel services. Many examples exist where this is the case for current or developing infrastructure technologies, but the positive impact of interdependency and complexity is rarely explicitly recognised.

Opportunities from Complexity
Infrastructure systems such as water, energy, transportation and telecommunication networks perform functions critical to the health and well-being of society1. Historically, such systems have largely been developed and maintained in isolation from one another; however, modern technologies and demands have given rise to an unprecedented degree of complexity and interconnectivity between previously disparate networks. Infrastructure now functions as a ‘system of systems’, exhibiting complex adaptive behaviour with numerous interdependencies that can leave critical functions highly vulnerable to disturbance through cascade failure effects1–3. Consequently, a majority of research efforts into infrastructure interdependencies have focused on risk and vulnerability, placing a primary focus on the negative aspects of system complexity.

Research at Cranfield University is exploring the ways in which infrastructure interdependencies can in fact be seen positively by representing opportunities to increase system resilience and sustainability. Darren and his colleagues have proposed a three-stage typology whereby positive interdependencies can be classified and understood according to the intensity of their interconnection. Knowledge-based opportunities recognise the potential for understanding and expertise to improve standard practices when shared across industry and sectoral boundaries and applied in novel ways through collaborative efforts. Geographical/physical opportunities arise where multiple systems can benefit one another through infrastructure sharing practices, increasing efficiency through the identification and reduction of avoidable costs. Integrative opportunities represent the most tightly-coupled variety, where two systems are interconnected and interdependent through shared functioning.

Inspiration from Nature
Infrastructure systems have largely originated from a traditional systems engineering perspective, in which design principles are goal-oriented and deterministic; however, the complex and interdependent nature of modern global systems has forced the adoption of more systematic perspectives4. Ecological systems exemplify ways in which complexity can build resilience rather than vulnerability, and as such their key principles of interdependence, cyclical flows, cooperation, flexibility, and diversity5 are explored in the context of current and proposed infrastructure developments.

Current examples of interdependencies being exploited to produce benefits include the development of smart infrastructure networks, efforts to work toward a circular economy, infrastructure sharing, and cross-industry efforts to adapt to the risks posed by global climate change. These examples, either realised or planned for future development, represent economically viable ways in which infrastructure interdependencies can be used positively. Benefits can take a variety of forms; increasing the quality of services delivered, increasing the efficiency with which this is done, creating and delivering entirely new services to respond to shifts in demand, and fundamentally increasing the sustainability and resilience of the overall system of systems. All of these are relevant and essential to the needs of modern infrastructure systems when considering the uncertainties and risks associated with growing populations, anticipated and unanticipated changes in stakeholder demands, and global climate change.

Next Steps
Viewing complex infrastructure systems through the lens of ecology enables us to better understand the dynamic nature of its complexity, which in turn enhances our ability to turn it to our advantage. Such integrative thinking is necessary not only for understanding and mitigating risks to system stability, but also for identifying opportunities to make complex human-created systems more sustainable and resilient.

This research is planned for publication in a forthcoming scientific paper. The upcoming CIRIA event ‘Infrastructure Interdependence in Practice’ in London on 21 March will also explore related issues and considerations, enabling industry practitioners to engage with CIRIA members. The exchange of knowledge and expertise across traditional boundaries is a critical first step in understanding the complexity and interrelationships that now characterise infrastructure systems, and such opportunities to connect research with practice are vital to forming a systematic understanding and the resilient functioning of global critical systems.

Full details on CIRIA's infrastructure and resilience series and the upcoming events are available at To register for one of the upcoming events please visit 

1. Rinaldi, S. M., Peerenboom, J. P. & Kelly, T. K. Identifying, understanding, and analyzing critical infrastructure interdependencies. IEEE Control Syst. Mag. 11–25 (2001).
2. Vespignani, A. Complex networks: The fragility of interdependency. Nature 464, 984–985 (2010).
3. Helbing, D. Globally networked risks and how to respond. Nature 497, 51–9 (2013).
4. Pennock, M. J. & Wade, J. P. The top 10 illusions of systems engineering: A research agenda. in Procedia Computer Science 44, 147–154 (Elsevier Masson SAS, 2015).
5. Capra, F. The Web of Life: A New Synthesis of Mind and Matter. (Harper Collins, 1996).