Large airport operational readiness (LAOR) is a critical factor that directly impacts the opening of airports to the public. However, limited research exists on the risks affecting LAOR schedules. This article explores the risk breakdown structure and risk interactions model of LAOR schedule risk. An empirical investigation was conducted on four large hub airports from 2009 to 2021 using grounded theory procedures. The study identified 21 risk factors categorized into management (highest frequency), technical, process, participant, and environmental risks (lowest frequency), which implied that risks primarily existed within a project rather than in the external environment. A systematic model incorporating risks and their interactions revealed that the primary risk transfer path was from the subject subsystem (participant risk) to the object subsystem (technical and process risk). The findings expand the knowledge domain of infrastructure risk and provide pragmatic risk evaluation and response guidelines.

Due to their characteristics and multiple objectives, high-speed rail (HSR) projects carry more complex risks than conventional projects and high correlation and conductivity are among the associated risk factors. Previous risk assessment frameworks for rail infrastructure have ignored the effects of risk interactions that inflate risk levels, namely, risk coupling effects. Based on a system dynamics method, this paper develops a risk coupling model for HSR project risk assessments. A risk factor list is established from a literature review, and relationships analysed using a case study and expert interviews. System dynamics equations are constructed and their parameters obtained by expert evaluations of risk factors. The proposed model is applied to a real-world HSR project to demonstrate it in detail. The model can evaluate the risk levels of HSR projects during a simulation period. In particular, it can identify the key coupling effects that are the main increased risk. It provides a significant resource, using which HSR project managers can identify and mitigate risks.