Here are some thoughts on how to arrange and conduct your business to best capitalise on BIM. These are based on experiences we’ve had in the past.
This post has nothing to do with operating a BIM system or BIM standards, but I haven’t seen this sort of advice anywhere else so I thought I’d write something down.
1. Project resource
If you’ve recently moved from BIM to CAD look at this simplified (and somewhat exaggerated) graph on the right:
This shows the resource requirements for a traditional CAD project versus those required for a BIM project.
With CAD projects, resource needs to increase in later project stages. Large numbers of drawings are created, so more coordination is required.
In a BIM project the focus is on developing the model. With a fully-developed model the resource impact for creating and coordinating drawings is lessened dramatically, as the majority of construction documents update automatically as the model is refined.
To get the model correct a BIM project must be ‘front-loaded’ with resource.
Do not resource a BIM project in the same way that you would resource a CAD project.
If you need to meet a sudden deadline or have to get a huge drawing package out do not catapult a large number of users at the project in the same way you might do when using CAD. This is often counterproductive and can create, rather than resolve, coordination problems.
We have found that small teams work best with BIM. On our largest projects we never have more than three people working on it and often it’s just one person.
2. Project pressures
Also if you’re new to BIM, you might be tempted to drop back into CAD when deadlines loom. That’s understandable, you might feel that you can get the work done faster in a familiar system.
I would recommend not doing this. If you are working in BIM it’s likely that you are doing so because of BIM requirements on a project.
BIM requirements require an accurate and information-rich model, this can be used for analysis exercises such as clash detection, information takeoff etc.
If your construction drawings are not derived from your model then you are endangering the productivity gains and savings that BIM offers. You are also possibly in breach of contract, depending on how thorough the project’s administration has been regarding BIM.
An example scenario is that you ‘drop back’ into CAD to get your drawings out, however you’re now-disassociated model is used in a clash detection exercise. Because there is no connection between your model and your construction drawings, the clashing exercise doesn’t pick up some issues, these are not discussed at DTM and they eventually become costly on-site mistakes.
Later on the project’s information manager discovers that your BIM data and construction documents have been disconnected. He points to the clauses in the BIM Execution Plan that say all construction documents must have a basis in the BIM model – and the whole situation could lead to legal proceedings.
3. Project data requirements
BIM projects differ from ‘traditional’ CAD projects as required data is expected to be contained in the federated model (everyone’s data in one place). This is so it can be used by all project participants during design and construction, and then later on during the operational phase of the asset, which is where most of the savings BIM promises are realised.