On the development of agent-based models for infrastructure evolution

Infrastructure systems for energy, water, transport, information, etc., are large-scale sociotechnical systems that are critical for achieving a sustainable world. They were not created at the current global scale at once but have slowly evolved from simple local systems through many social and technical decisions. If we are to understand them and manage them sustainably, we need to capture their full diversity and adaptivity in models that respect Ashby's law of requisite variety. Models of evolving complex systems must themselves be evolving complex systems that cannot be created from scratch but must be grown from simple to complex. This paper presents a sociotechnical evolutionary modelling process for creating evolving and complex Agent-Based Models (ABMs) for understanding the evolution of large-scale sociotechnical systems such as infrastructures. It involves the continuous coevolution and improvement of a social process for model specification, the technical design of a modular simulation engine, the encoding of formalised knowledge and the collection of relevant facts. In the paper, we introduce the process design, the requirements for guiding the evolution of the modelling process and illustrate the process for ABM development by showing a series of ever more complex models.