Clash Detection

BSBG Senior Architectural Technologist, Mark Vaughan on clash detection and the BSBG approach to it.

Clash Detection is a relatively new process within the construction industry, and it is starting to play a more integral role in the design of architecture in Dubai and across the world.

Why we run clash detection in architecture

There will always be an element of human error building design and the modelling of projects. This is unavoidable. We run clash detection to anticipate any issues that may have been missed during the design process, therefore reducing risk to the project program, cost and design.

Building Information Modelling

Working in a BIM environment has huge benefits in enabling the design team to undertake co-ordination reviews (clash detections) in earnest and with more accuracy, something which 2D delivery just does not offer.

Client Expectations

On certain projects, BSBG has encountered difficulties with a client’s interpretation of what is perceived to be a clash free model. As a result of this, the practice has recently developed unique BEP’s (BIM Execution Plans) to identify clearly what is deemed as a clash.

As stated above, this is anything which is of risk to the design, program and cost. The following are good examples of what might be deemed as clashes that must be eliminated from BIM models.

  • Door and structure – If these clashes are left in the model there is risk that a door is procured that does not fit within the opening constructed. It also highlights that there is potential risk to the functionality of the space.
  • Mechanical ductwork and structural sheer walls – Structural openings are more difficult and time consuming to provide after the structure has been cast.

The following are some examples of clashes that are acceptable:

  • Walls and columns – The structure is always cast first, therefore, there is no risk that a contractor would demolish a column to build a wall shown passing through the column. If a client is concerned over these types of clashes, then they should be questioning the contractor they appointed and not the clashes.
  • Sockets in walls – This level of clash avoidance is unnecessary, takes designers time away from designing and adds no benefit.

In some instances, leaving clashes in models can actually be helpful to the process. Some examples could be:

  • TV’s on walls – A contractor could run a clash detection between these elements and work out how much patressing is required within stud partitions and quickly identify locations.
  • MEP through fire-rated walls – The design team can run clash detection to check if all these service penetrations include fire dampers.

If a client requests a clash free model, it is often down to ignorance if they expect there to be no clashes within the model. This would rarely happen and is not something that would be aimed for.

Material take-offs

At present, quantity surveyors have some catching up to do when it comes to BIM. However, when BIM material take-offs for costing start to become more popularly used across the industry by quantity surveyors, then the requirements for less clashes may increase. That said, this will not mean completely clash free models.

It should also be noted that models built for material take-off would only apply to higher LOD (Level of Detail) projects. This would obviously be subject to increased fees as it requires more in-depth model management.

Other Software

BSBG’s BIM delivery tool is predominantly Revit. Although Revit is capable of running clash detection (interference clash), there is better software on the market available to undertake this task. At present BSBG predominantly uses Autodesk Navis Works to undertake clash detection on every project.

While Navis is certainly a leader as a clash detection tool, there is still a lot of room for improvement in terms of user interface.

There is also other software on the market that could in the near future be the preferred clash detection tool. One of those that is worth investigating is Solibri.

On the surface, the clash detection and design review capabilities are hugely impressive within this software. Solibri could review such design issues as fire escape distances, corridor widths, lift lobby spaces, etc. It also provides the opportunity to export issues flagged and import them into the Revit model to speed up the process of rectifying issues.

Although it is impressive as a piece of software, upon further review Solibri is still very much in the early stages of development, and is not completely ready for use. However, Solibri could well be the future design review tool for BIM and bring a new level to the collaborative world we now design in.