What is Clash Detection?
Employed during the design phase of construction project coordination, clash detection is the process of identifying possible material collisions on a future construction site.
Softwares like Autodesk Navisworks or Solibri are able to consolidate various model designs from architects and engineers of different specialties, and check that the placement of their structures aligns (for example, if a duct is occupying the same space as a pipe).
Why do we do Clash Detection?
The file sizes of architectural or engineering models are so large and detailed that it doesn’t make sense to have every specialty work on the same model at once.
Instead, construction projects involve each specialty working on their own separate model, submitting their models to a BIM manager, who in turn consolidates these into one. From there, the BIM manager identifies clashes and assigns them to the right specialty to be fixed.
What Happens if a Clash is not Detected?
It’s possible that a clash is not detected before the construction begins. Unfortunately, this usually leads to work delays.
Eventually a contractor will see an issue, such as a big support beam right in the way of where a pipe is supposed to run (according to the model). They will send an RFI to ask how to handle this issue. Maybe the issue will require deviating the pipe, or maybe it will require reworking the already-built structure. No matter the solution, it will add unforeseen materials, time, and costs.
That’s why it’s best to resolve these issues early, with clash detection as part of the model coordination process.
What is 4D Clash Detection?
Not all clashes in a model are physical (such as two intersecting structures). Some are temporal.
For example, if a crane will be in operation for a project during certain hours, but the truck that delivers beams won’t be scheduled to arrive for another 4 hours, that time difference constitutes a clash: machinery and its operators are being paid for, but cannot accomplish their tasks.
4D clash detection aims to resolve clashes in time as well as space, and set realistic schedules so that the work can be completed smoothly.