Projects have increasingly tight deadlines, and therefore the days when it was possible to wait for project completion to estimate costs and begin the contracting process are gone. So how do you determine if a model, or an area of the project, is mature enough to begin negotiations with suppliers of materials, services, and equipment? There is a definition table developed by Vicosoftware, a company specializing in cost control for projects (acquired in November 2012 by the Trimble group, which owns Tekla and SketchUp). This table is called... LOD – level of detail or ND – level of detail.
The idea is as simple as it is practical and functional. There are only 5 main divisions (each project can subdivide the table according to its time requirements and available resources).
- Level 100: The data is in the draft and spatial allocation phase. The results are only sketches of the element distribution. At this stage, the processes are tested and redefined in order to find a better fit for the realities imposed by the construction. At this stage, it is common to have only schematic 2D drawings, diagrams, flowcharts, data tables, and some formless 3D objects, only to symbolize trials of possible arrangements.
- Level 200: The 3D objects are already approaching the volume of objects in the real world. The geometries of the objects and the spaces necessary for their operation are defined and validated by engineering. At this stage, we verify interferences and reserve space for assemblies.
- Level 300: The allocation of objects in 3D is definitive (for the design environment; it may be revised in a construction environment). The processes are already mature and the necessary engineering calculations are complete. The component variables have been populated for the correct sizing of the equipment (data sheets). All model functions have been validated; the processes, layouts, and construction documentation can be extracted from the 3D model.
- Level 400: A technical engineering team is mobilized to find and approve potential suppliers of materials, equipment, and services capable of technically meeting the construction needs of the project. At this stage, information collected from potential suppliers, which will be useful during construction and assembly, is inputted into the 3D model. For each component to be negotiated, there are part numbers from several potential suppliers to be priced. A schedule (timeline) for assembly and construction must also be prepared, in line with the availability of materials and resources in the market, to provide timelines for pricing negotiations.
- Level 500: The procurement team, equipped with the information in the model, then steps in to finalize the contracts. Acquisition, contracting, and construction data must be entered into the model to serve as a reference for the continuity of the project's operation and maintenance. The model contains purchase orders, quotations, notes on pending services, preventive maintenance forecasts, equipment consumables lists, possibilities for replacing similar components, and other data collected during construction. Maintenance information, throughout the project's lifespan, should be returned to the objects in the model to maintain a history and assist in fault diagnosis.
In summary, we have the following concepts:
- ND / LOD 100 = There is one thing.
- ND / LOD 200 = There is something that occupies this space.
- ND / LOD 300 = There is something wrong with these functions and options.
- ND / LOD 400 = This particular thing.
- ND / LOD 500 = This is the actual item, supplied by this company, on this date.
Another representation of these levels of detail, in a more detailed and specific way, would be the image below:
Within a complex project, there may be objects, or entire areas, at different LOD levels, depending on the project's progress. Each user of the model's information must interpret the data, taking into account the LOD level at which the information is located, in order to make more informed decisions.
Now, the point that deserves highlighting and reflection: Companies contracting "BIM Engineering" are not prepared to remunerate design and detailing companies considering the LOD/ND of the project, or even to pay for the BIM project itself, and continue to remunerate contracts based on the generated documentation. This is a mistake, and there needs to be an ideal contracting model, because technology has evolved, but the processes of supervision, contracting, and documentation cannot remain tied to the "old" and conventional method.