Building Information Modelling (BIM)
Building Information Modelling (BIM) is a method for process optimisation in the planning, execution and operation of buildings and structural facilities. The basis for this is the interdisciplinary development, provision and maintenance of all building-related information in a central data system. This is represented in the form of a digital building model.
BIM involves the creation of 3D models of a structure or infrastructure. These models are composed of individual components and spaces that have been defined in advance. The geometrical information is defined, which is then supplemented by further information for the components, for example on material, expected service life or properties such as sound transmission or flammability. The rooms are described separately. Properties such as the desired volume or later use can be attributed to them. If, in addition, information on costs and/or the time schedule is stored, these are referred to as four- or five-dimensional models.
The digital model accompanies the building or facility throughout its entire life cycle: all planning and projects are based on this digital file as a "single-source of truth". The advantage of BIM is that detailed planning is at the beginning and not later in the process, according to the motto: "First build virtually, then in reality".
The IFC (Industry Foundation Classes) Rail data exchange standard is intended to take into account the special conditions for railway infrastructure. Involved in the development are China Railways, Deutsche Bahn, Austrian Federal Railways (ÖBB), Swiss Federal Railways (SBB), French SNCF, TVK from Sweden and the International Union of Railways (UIC).
In Germany, the Federal Ministry of Transport sets out detailed specifications on how the BIM process is to look. BIM must be defined as a procedure in the contracts. The client is required to specify right at the beginning what data he wants to receive from the contractor, in what form and in what level of detail (client information requirements - AIA).
Advantages of BIM
In practice, 3-D CAD modelling is becoming more and more accepted compared to 2-D CAD drawing, since 3-D models can be used more efficiently. This gives the client a realistic picture more quickly, which makes it easier to make adjustments. Possible problems in spatial planning are already apparent in the model. Additional information required for applications or evaluations can be stored there.
BIM reveals weak points early on. Detailed planning right at the beginning of a project and the detailed checks specified in the BIM execution plan increase the quality of planning. There is more certainty about deadlines and costs. Variants can be transparently weighed against each other, and solutions for cost reduction can be sought early on.
BIM is not only used for new buildings. The advantages in planning can also be used for extensive repair measures. The first step here is digital, BIM-compliant recording. For example, during the rehabilitation of the Mannheim-Stuttgart high-speed rail line, the route was no longer inspected by foot, but digitally recorded using georadar, laser scanners and cameras. Ground-Penetrating Radar (GPR) is a method of penetrating electromagnetic radiation into ground surfaces. The range is 1.5 to 2.5 m depending on the nature of the ground. The type of reflection of the rays provides information about them. This enables structures close to the surface to be explored - in the case mentioned, the lower edge of the gravel was detected.
In the concept of the Digital Twin, a real object has its exact counterpart in the data world. In BIM, at the end of a construction project, a 3D model is handed over in its final state, i.e. the Digital Twin. With subsequent continuous digital monitoring, this Digital Twin changes permanently and always reflects the real state. BIM and digitalised maintenance come together in the Digital Twin.
The BIM method is not limited to buildings and infrastructure. The same logic of the components defined in object catalogs, which are assembled in the 3D model, can also be used in the process optimisation of machines and plants.
Recommended specialist books:
Rees, Dagmar, Digitalisierung in Mobilität und Verkehr
Schütze, Christoph, BIM applications for track maintenance