How to avoid the problems with bim
Bim is trumpeted as the one-stop future of construction, but the reality is not as simple as it seems
The marketing engines have been promoting bim as the future for a number of years without actually delving into the detail. However, even the most committed bim convert will relate initial drawbacks to implementing process change and making the switch. There will be hurdles to overcome and new problems to deal with that really should be examined and understood before any fresh implementation is considered.
The demo vs the reality
Bim is presented as a one-stop solution. Simply build a single, data-rich model and everything will be produced near automatically – plans, sections, elevations, quantities, renderings, costings and even perhaps the energy certification. It is a utopian vision.
The actual single model is really a dream. An architectural bim model is quite different from a construction bim model – while the geometry may be the same, the information is different
and the construction scheduling requires elements to be broken down (eg how many concrete pours for the floor). Companies like Tekla create models for constructability and fabrication, with the corresponding detail. Vico also creates bim models for quantity, cost, scheduling and production control.
Dealing with change
The workload changes and shifts forward many design decisions. Before starting a project, new “families of parts” (intelligent components) should be created, which may bring forward decisions on interior fittings such as doors and windows, escalators, lifts and glazing. The level of detail in the model is also highly important – too little and the benefits of modelling would be lost, too much and the model will become too big to load and manipulate. Medium to large buildings need to be be “cut up” to be manageable.
Adapting output styles
One simple problem is that the automatic output of 2D plans, sections and elevations has a style which many firms do not appreciate. Customers expect drawings to conform to their own internal standards. Many send these through an AutoCAD user to “tart up” and lose one of the big benefits. Any changes to the model will update the drawings and these will all need to be hand-edited again.
Changing a long-established way of working is always going to cause problems and bim has its own issues that need addressing. Obviously there is the “people” issue: staff skills need to be upgraded and new staff will need bim understanding. Internal processes will change and new teams will be built. Most bim tools are “easy-in” but the devil is in the details and there is a fairly steep learning curve.
Industry and data standards
Standards are a major industry issue. First there are internal standards and then there are the data exchange standards. For the internal standards, a workgroup has defined the AEC (UK) bim standard, a template to be downloaded and incorporated into an office’s protocols. The standard has no legislative backing and is unfortunately biased toward Revit users.
The cad industry has always been terrible at data exchange. With bim, it appears that the competing software players are taking interoperability to new lows. Bim models have complex 3D geometry, behaviour, parametric and lots of information attached to each object and the only real standard is IFC (Industry Foundation Classes). This is an independent documented standard, which the vendors interpret and implement at their leisure. The end results are hit and miss, but IFCs are the only real hope and one can only wish that this improves. For now a number share data through the 2D drawings (DWG and PDF).
The last cultural issue is of course the contract situation, which does not account for the levels of integration and data-sharing that bim enforces. A new type of contract is required when tackling projects as the overall liabilities must be shared. Bim favours design builders; traditional federated projects require a new attitude to liability of deliverables.
Depending on the software, bim models get big, fast. David Light from HOK told me the firm is stipulating 24GB of ram for its new workstations so they can hold the Revit datasets without paging to disk on their biggest projects. This is a considerable investment: you simply cannot run bim on old machines designed for AutoCAD or VectorWorks. Other bim modellers are not quite as memory-hungry but still start to swell as the model detail grows.
Finding like minds
Another obstacle is that, if you are using bim, it pays dividends to work with firms of a similar mindset. With the interoperability issue, it helps if you are on the same system – Revit Architecture to Revit MEP or Bentley Architecture to Bentley Structural. With bim still in its formative stages, adoption is thin on the ground, especially within the MEP industry. As adoption accelerates, this will become less of an issue.
Building information modelling is widely seen as the next technology for the building industry and rightly so. But adoption will require adaption, investment and greater teamwork between the core trades. A variety of issues still need to be overcome both in the technology and between developers. Experience suggests that after three projects most firms really see the benefit of the move to bim but there are also failures, albeit co-ordinated ones.
Martyn Day is editor of AEC Magazine, a bi-monthly journal for construction professionals.