LOD - Level of Detail, Level of Development, or Largely Over Disputed?

Found a great post this morning that I thought I'd share about LOD and BIM.


http://www.allthingsbim.com/2012/03/moving-forward-with-lod.html


The author James Van is pretty dead on.  There is no such thing as LOD models for BIM.  It is much more granular than that.  "LOD" is a rule of thumb for the level of progression of a model at various points of a project.    However, as an owner it is not reasonable to expect nor should you just blankly accept a LOD XXX model.  LOD (for purposes of this example, I say "level of detail") should refer to the information within the elements of the model and its systems.  Meaning with each level of model progression, a deeper level of information shall be provided.  Now here is the tricky part...even though it is considered the "as-built" level, LOD 500 may not be appropriate for all elements of you model.  In fact, you should only expect LOD 500 of those parts of your model which you know will need to contain data critical to your maintenance and operations staff.  At LACCD, we have started to identify those simply as model, manufacturer, material, location, system information, and performance data.


You could also ask your teams to add links to  O+M Manuals, Training and Safety Videos,   Warranty Data, and maybe even record drawings.  You could even ask your team to include this data in a CAFM (Computer-aided facility management) System if your organization has one.   However, as you can see, only some of this information is actually model data. This may be why LOD is generally referred to "Level of Development" since not all levels of "D" are equal in the weight of information to be provided. In fact, modeling a particular part of a system such as mechanical ducts or structural steel at an LOD 400 may actually be more appropriate for a fabrication model than an LOD 500 because this level of development refers to data pertaining to assemblage, parts and pieces, and construction and installation details.


Be careful what you ask for. 


As an Owner, you could ask for every element and system to be LOD 500; but if you do, expect the price of your BIM deliverable to jump dramatically, and the return of your investment to decline in the same manner.  Some building elements (interior partitions, for example) do not really need a manual or maintenance data to operate.  For this reason, you may want to ask your team to provide their own Model Progression Specification as part of their BIM Execution Plan.  You should then carefully review this and see if it meets your expectations for what you require to receive at the end of the project.  You may also want to check the progress as the project moves along, with some sort of Model Progression Spec or Model QA Validation process of your own.  As we tell many of our College Project Managers, even though we deal with many Design-Build Projects where collaboration is to be expected, you should trust but verify.  An LOD or Model Progression Spec won't be able to do that alone.  It will still require you to have a process of reviewing the models and content and tying it back to your requirements.  Likewise, using a system that refers to COBie may help with the data, but it won't tell you if  your model is assembled incorrectly or missing linked files or details.  Therefore, a more visual approach is needed.


"Walk" the model  

Clash free does not mean coordinated - Not all coordination issues are clashes.  Therefore, it is important to "walk" the model just as you might a construction site.    

In the true context of BIM, the model your team develops to document the design and construction of the building should ultimately be a virtual representation of the building itself.  Upon final delivery to the Owner, the record model should have accurate geometry and data that reflects the actual systems and their location.  If it does not, then what good is it to your future building users and operators?.  This is also where the use of LOD really has no ability to gauge the quality of the model itself.  You need to see it to believe it.


A couple of years ago, while reviewing a BIM deliverable, one of our project managers referred to the process as a Virtual Punch List as we started to mark up constructability and maintenance concerns within a consolidated coordination model that was supposed to be "construction ready."   This process has now evolved in to a fundamental part of our model review, as it helps stakeholders to begin to better visualize a building they once only knew in 2D.  We then include the models and markups and a spreadsheet of our quality assurance review and send it back to our consultants for their comment.  This continues up through building completion, and until project close out, and may also include participation of facilities staff, construction safety managers, and accessibility experts.


The bottom line is do not rely upon "LOD" alone to deliver you the model you expect.  Require your team: owner, designer, and builder alike, to really analyze the model and its content.  The LOD can be a good gauge, but unless you literally open up the model and have look...you don't know what you don't know.