Building Information Modelling (BIM) is defined by ISO 19650-1:2018 “Organization and digitization of information about buildings and civil engineering works, including building information modelling (BIM) - Information management using building information modelling - Part 1: Concepts and principles: as: “use of a shared digital representation of a built asset to facilitate design, construction and operation processes to form a reliable basis for decisions”

In other words, BIM is a process that involves the generation and management of project and asset information using digital representations of physical and functional characteristics of structures and facilities over their entire life cycle. Moreover, this process is supported by various digital tools and software as well as by contractual information management agreements. For this reason, in current practical usage, BIM is often used as an umbrella term to describe the use of any number of digital tools, such as, but not limited to, 3D modelling, computational design, visualization, clash detection, 4D/5D modelling and information management used to improve design, project delivery, asset management, and collaboration.

While the ITA WG 22 does not purport to have the authority to provide a definitive description of BIM, the text above addresses two common issues. First, in describing BIM as a process, rather than as a single software, program, model, or data structure, the definition provides a technically accurate description of BIM in line with ISO 19650. In contrast, the final sentence of the paragraph above addresses the reality of the usage of the term ‘BIM’ in the tunnelling industry. While experienced BIM professionals may consider BIM to be primarily an information management process supported by tools such as 3D modelling, less experienced BIM users tend to refer to the 3D models or 3D modelling tools themselves as BIM. The text above aims to reconcile this divergence in perception.

When fully implemented, BIM involves the creation of a central storage location for all digital information of the project/asset during its lifecycle, from design to operation and maintenance. This information is stored within a multitude of BIM Models that accurately capture the desired project/asset information at each project phase. The BIM Models together with the information management/storage system with which they are connected make up the ‘digital assets’ of a project.