To achieve technical excellence and a successful outcome to a project, it is essential that BIM working and subsequent information and drawing production output is carefully planned. This must involve explicit attention to management, display and quality of the design data. Below are a number of best practice key principles that will aid efficient, high quality working.
- Determine project requirements for BIM, Regardless of the existence of an EIR, key is what graphical (Level of Development (LOD)) and non- graphical (Level of Information (LOI)) information is required and when.
- A Project BIM Execution Plan (BEP) appropriate to the project stage shall be put in place that identifies who is responsible for key project tasks, outputs and model configuration and how project requirements are to be met.
- BIM project reviews should be agreed and take place regularly to ensure model integrity and project workflow is maintained, to achieve the project requirements, and that the BEP is being followed and maintained.
- It is imperative for smooth information exchange that clear guidelines are developed for internal and external collaborative working which maintain the integrity of electronic data. This is equally important for employer’s decision points, suppliers’ information exchange and the iterative model exchange of design data between these more formal deliveries.
- Identify clear ownership of model elements through the life of the project.
- Sub-divide models between disciplines and within single disciplines to avoid file sizes becoming too big or slow to operate within the agreed project volume strategy.
- Understand and clearly document Modelling Methodology. i.e. what is to be modelled and to what Level of Detail. Do not over model.
- Do not over Document (be careful at early project stages in particular).
- Define clearly the data (Level of Information (LOI)) to be incorporated into the BIM relevant to the stage.
- Together, the LOD and LOI help to better communicate the expectations of BIM content and clarify the Level of Definition at any point in the design and construction process.
- Level of Definition = LOD + LOI
- Avoid disconnect between the main 3D model and 2D views or output. Revisions to the project should be made “at source” (i.e. in the model) to rather than editing the 2D to ensure the integrity of the model and coordination between the BIM and its output.
- Outstanding warnings shall be reviewed regularly and important issues resolved.
Where drawings are a product of the BIM, traditional drawing conventions still apply, for example:
- A drawing shall contain design information solely for the purpose of the intended use of the drawing.
- To maximise efficiency, a policy of minimum detailing without compromising quality and integrity shall be adopted and repetition of details should be eliminated.
- Numbers of drawings should be kept to an absolute minimum and organised in a logical manner.
- Avoidance of duplication is essential to ensure drawings maintain their integrity as the iterative design process progresses and amendments are made.
- All drawing symbols used should be in line with industry standards.
Of course, 2D documents must be derived from a coordinated, federated, clash detected set of models. The CIC BIM protocol states that if there is a discrepancy between what is delivered in the form of the models and the 2D .pdfs that it is the federated model data that should be referred to as the primary data source. You cannot just do your 2D work and then deliver a model as well – the model has to be what is delivering the 2D output in the first place.