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Monday, April 05, 2021



A Contractor’s View of BIM (part ii)

Interesting read. Paints an idealised workflow that has its benefits as well as problems. See ENG 2018 vid on GC-led modeling.


Agree with the laundry list of problems but I don't think just going GC is going to solve that much. In the Mid East and Japan, big construction companies have always done the bulk of the detailed design work inhouse. In France, the contractors also use bureau d'Etudes as inhouse design and coordination resource. In would be good to get their views having done this a lot longer.

At the end of the day, pentels and sketch paper for everyone else is unrealistic... except for very simple buildings. Ironic that TutorPerini's motto is 'Building Relationships on Trust' :-)

Looking at a lot of the complaints. What is needed is better collaboration and information transparency. This means better digital tools.

Designers may lack technical nous, but Contractors are not much better, bro. They have just specialised and been at it longer and commercially incentivised.

Starting with paper CDs contradicts the real benefits made thru BIM, as problematic as it is. Analytical models (structural and energy etc) are here to stay.

Drawing duplication inefficiencies are a red herring. How is "creating a new series of models from scratch" better? The key to to filter and harness whatever info is available.

The key problem for contractors is that they have always struggled to identify problems in time in the bid documents. IPD was meant to give them the time to price the job so you don't have to rely on your 'rainmaker' estimator weighing drawings in his hand. What a mad idea!

Instead of going voodoo, contractors have been using 3d estimating tools like Destini and RiB etc to cost model the bid design using the 3d model as a basis. This is not the same as 'clean room' semi reverse engineering the design as suggested.

I also think that the savings wrt foreign standards and 'modeling oddities' is overblown. Sounds like they just haven't figured how to work Ideate et al to remap info.

Hiring experienced modelers and engineers inhouse is not as easy as portrayed. Main reason IPD fails is that your specialist subbies' biggest asset is their design staff and knowhow and they make their money from the install not the design service. Good luck with getting the expertise in house at low rates. What you will end up with is just BIM jockeys who don't have the tech knowhow... importing risk in for the GC.

Lots of complaints listed are the result of making the best of the existing BIM tools blindspots: bad 2d/3d CAD in BIM interop (Revit).. the clash detection fiasco (mainly because Revit etc can't Xref live dwg etc very well and relies on asynch declashing using Navis), ditto on lack of modeling in context, low or no LOD (mainly because Revit etc bogs down when things are 'overmodeled')etc etc

It would be better to focus on these issues instead of grand gestures. Not against GC-led modeling, but that will only go so far.

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