Reactive vs Proactive Approach for 5D Models
by Marcel Broekmaat
While the use of Building Information Models is getting more and more popular, it seems that the full advantage of using the model-based approach for informed decision making when it comes to cost planning and scheduling has yet to be experienced. In my opinion, the reason for this is that many building models are created with a “hit-and-run” approach: Building Information Models are created for projects without considering what the desired output should be.
The models that are created this way can be great for visualization and maybe even for coordination. But, because there is no defined set of requirements before the modeling work takes off, may be useless for estimating and scheduling…
Why is that?
It all comes down to quantities. It’s the construction-caliber quantities that drive the estimate and the (integrated) estimate and schedule and when some of the quantities that are needed are not available, the “5D Mission” fails: only some of the quantities extracted from the model are useful. Some quantities are too detailed for the stage of the project, other quantities are simply missing. The only use for the model for estimating purposes in this case is to find opportunities to find model-based quantities that happen to be useful. I call this the “reactive approach:” trying to find some good use for the model that was created when it’s done.
There’s a simple remedy for missing the opportunity to extract quantities from models that do match the requirements at a certain stage in your project. At Vico, we call that remedy the Content Plan. The Content Plan is nothing else than a document that captures the information needs of all of the members of the project team for the deliverable at a certain stage in the project. (Think of it as a model progression specification for only one stage of the project.) When the project team gets together to define these goals before the model gets built, it is much easier to build something that fits and really turns into a tool that helps your team make those important decisions.