Friday, April 10, 2020

Stay Home Learn BIM: week 3 – Be wary of the Bully BIM! (bonus Easter Egg Hunt)

There is one type of BIM, that I call the Bully BIM.
It is a bit of a ‘below-the-belt punch’ kind of BIM approach.

It is called ‘Clash Detection’.
At its essence, it is a well-intended concept.
Unforeseen clashes of building elements cause a lot of trouble when discovered during construction and subsequently slow progress down, result in abortive works, extra materials, labor cost and lengthened programs. Using technology to eliminate (or at least minimize) such issues on the construction site makes sense.

And it doesn’t. At its premise is the idea, that following semi-independent work done by many consultants (in model-base or otherwise) an automated procedure identifies the clashes of spatially conflicting elements and highlights them.
But in practice, it is an ignorant and arrogant approach, used to gain points over something or someone and rarely works to the benefit of the project.
It is ignorant as it ignores the reality of design definition development in contemporary construction projects being continuous through to the completion of the building.

There are no fully designed/modelled projects that can be effective clash-detected.
There might be really well designed and modelled projects that everyone worked together throughout the design process and the resulting model is ready to be built from.
In those rare cases automated clash detection ‘interventions’ will add little value, so why bother.
And then, there are the majority of the cases where clash detections is forced onto partially defined-partially documented projects and the outputs are reports going into hundreds of pages of ‘issues-needing to be looked after and dealt with’.

Those reports shoot the entire BIM movement in its foot and make building modelling as a field look dumb.
Yes, building services should be well designed and coordinated before everyone hits the site and scrambles for their place within the zone allowed.
Sure, major dramas happen when there just isn’t enough space within ceilings, ducts and risers for everything that needs to be put there.

But clash detections aren’t there to find these major dramas, they are done, to score brownie points for a clash detector.
It is extremely likely that those major dramas, even if picked up will be buried so deeply within Clash Detection Reports that will be lost in the sea on insignificant ‘move the pipe 25mm to the left’ – responses and stay unresolved. (meanwhile many hours are spent on managing the administration of ‘issues’)

Paying a lot of money for someone to clash detect a model created by someone else is counter productive.
Paying someone a lot of money for someone to model someone else’s design, so it can be clash detected is even worse.

Over the years, I wrote regularly on this topic.
So, being Easter and a time for various games, let me propose one here:
Go through my blogposts (595 including this one) and find the number of times I mentioned ‘clash detection’ in them. Put the number down here in the comments.

The author of the closest number posted before the end of April (Midnight NZ time on the 30th April) will win an A3 sized, hand made mosaic of their chosen portrait picture.

For examples, see here:

Do I believe, people will take on this game? Nah.
So, let’s add that, the number needs to be within +/- 5 to qualify.
If no one enters I’ll just carry on with my current mosaic project.


  1. Replies
    1. Hello Gabor! You won the competition.Email me a photo of a picture you'd like me to mosaic. It will take me about a month to complete and post to you. Thanks for entering!

    2. I just started reading your blogs. You got the swag!! loved them.

  2. This comment has been removed by a blog administrator.

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