A Systematic Review on Complexity in Collaborative Infrastructure Projects

Projects in the infrastructure sector are becoming increasingly interdependent and complex, and how to deal with that complexity is something to pay close attention to in the process of developing a sustainable society. This article sets out to provide an overview of how complexity is dealt with in real projects and thus asks the question of how complexity is considered in scientific literature, based on empirical studies about collaboration in infrastructure projects. Consequently, this article presents a structured literature review using PRISMA. Three scientific libraries were used: Web of Science (for 1 January 2000–31 December 2023), Scopus (for 2000–2026), and OpenAlex (for 2024–2026). The search query included complexity, collaboration, infrastructure, project management, and case study, as well as synonyms. A total of 43 articles were included in the final sample for the review. Interestingly, the analysis of the sample reveals that the initial expectations were not met, so instead of creating a comprehensive overview of the methods used to deal with complexity, a different discovery is made instead: complexity is often mentioned, but is hardly defined, barely operationalized, and not understood.