This study analyses the dynamic and complex structure of megaprojects using a bottom-up approach that starts from the individual Work Packages that comprise the infrastructural megaproject, providing a first step toward analysing the complexity of the entire project framework, including labour, supply and product markets, governance, licensing, etc. The study reviews the planning and management methodology, with a focus on the workforce needed to complete the work within the expected time and cost. In this study, the workforce patterns of a real infrastructure project are analysed using the System Dynamics (SD) approach. The underlying dynamic hypothesis has led to the identification of a Stock-and-Flow model of the construction process. The analysis of field workforce patterns was conducted to understand lessons learned, specifically why the actual performance differed from the planned performance in terms of time and cost. Moreover, the study provides a general modelling method for the simulation of the construction process of any industrial infrastructure. Such a modelling method reproduces the physics of the construction process, including mobilization and demobilization of the workforce. It leverages feedback-driven recovery actions for project control. If applied to new projects, the modelling method can allow the Project Manager to develop the project's risk analysis and to be assisted in keeping the performance of the assembly resources close to the planned level during project execution. The proposed method could improve returns from infrastructure construction investments due to better planning and resource control. This improves their use, reducing delays and litigation.