In this post, let’s look at some of the workflow implications of my proposed SOI approach to BIM data management, with the use of GR levels instead of LOD, by walking through a simple project to build a reinforced concrete column.
1. First we need to clarify the overall information-exchange process. It will look something like this:
2. Looking at the process map, we can determine the varied “BIM uses” involved, i.e., the tasks or processes for which we’ll need to use the BIM model. Note that we’re talking about a single model, a common environment, made with whatever mix of software, and about how we’ll use that one model.
3. Based on the intended BIM uses, we can set GR levels at each point in the workflow.
Note that it’s not a simple accumulation of more and more detail over time, of progressing from GR1 to GR4 and staying there! In fact, there’s no need for GR4 objects in this case, and we end up with a GR2 element in use. Moreover, different actors, even working simultaneously, sometimes need and should get different levels of detailing.
4. Now for the data exchanges: the milestones and drop points. Remember: our goal is to give each BIM actor just the data they need for the task they have to do at any given moment.
Each process, or BIM use, has an input and an output (shown with black and red dots). The input for a process corresponds to output from a previous process, and that’s a drop point. In other words, at a drop point, the output from one process supplies inputs required for the next process.
Milestones are decision-making moments, often a team meeting or design review. They’re shown with heavy black arrow in the diagram. Decisions are made there about how to solve problems, how to proceed, and – above all – whether the prerequisites have been met in order to move forward.
Milestones are processes themselves. Often the result is having to go back to previous processes to fix something that’s not quite right. As a result, the number of drop points for any stage is potentially infinite. But the number of milestones for a project is fixed – here there are 5.
With this example, I’ve tried to illustrate the intuitive interplay between GR levels and BIM uses over the lifetime of a building project. I’m convinced that this approach has the potential to boost BIM workflow efficiency significantly.