Understanding Emergent Behaviour within Infrastructure System-of-Systems (EBISS)
The UK’s economic infrastructure can be viewed as a complex system-of-systems exhibiting emergent phenomena and behaviours. Interactions between constituent systems, and between the these and the whole system-of-systems, give rise to behaviours and characteristics that are not present in any of the individual infrastructure systems themselves. Such emergent phenomena include beneficial characteristics such as integrated transport, sustainability and resilience, but also unwanted emergent failures, i.e. unexpected disruptive events at the global level that arise from complex interactions involving local level constituent parts.
Working with the National Infrastructure Commission, this project looked at developing a ‘joined-up’ understanding of ‘emergent’ failure events within the infrastructure system-of-systems. With the increased prevalence of flooding and other extreme events it is important to understand how the behaviour of one system can affect the behaviour of another, to bring about disproportionate impacts or hamper recovery.
Case Study Emergent Failure Events
The review explored the nature of emergence in the context of the national economic infrastructure system-of-systems. It identified and described the following eight real examples of economic infrastructure experiencing significant failure events that were identified as exhibiting emergent behaviour:
- Howard Street Tunnel Fire, USA, 2001
- New York Power Cut, USA, 2003
- Buncefield Explosion, UK, 2005
- Gloucester Floods, UK, 2007
- Superstorm Sandy, USA, 2012
- Storm Desmond, UK, 2015
- Low Frequency Demand Disruption, UK, 2019
- Victoria & London Bridge Disruption, UK, 2019
Future Toolsets
Most traditional methods for conceptualising failures and designing resilience reduce system-of-systems to their discrete constituent systems. They are largely based on sequential chains of causality which tend to ignore interactions between constituent systems and between the constituent systems and the overall performance of the system-of-systems; focus on the local level within a constituent system; and seek to produce only prescriptive interventions. The following Systems Theory approaches were proposed to address these shortfalls and help diagnose and manage emergence:
- AcciMapping – a visualisation of information and decisions as they are communicated up and down hierarchies of control between the local level parts of the constituent systems and the overall governance at the system-of-systems level.
- Functional Resonance Accident Model (FRAM) – a tool for modelling the combinations of performance variability across the functions from which the system-of-systems is comprised.
- System Theoretic Accident Model and Process (STAMP) – a process for identifying inadequate enforcement of constraints, inadequate control and feedback mechanisms by modelling the hierarchical control structure and interactions within the system.
This project was led by Dr Neil Carhart, with contributions from Dr Maria Pregnatola and Dr Ges Rosenberg.
The full report prepared for the National Infrastructure Commission can be found here.