From comments I have garnered it seems the consensus is that engineers will have to model accurately for BIM to work. There was a lot of talk about the many issues that will need to be resolved, work practices that must change, and fees that need realignment, but no alternative strategy to create true BIM materialised.
In my previous post, Should engineers model accurately, Method 4 - Engineers Model Accurately was the only one that received any support, or even serious consideration.
The most common objection (from engineers) to modelling accurately was that "their fee didn't cover it", or "there isn't enough time", which is the same thing. This may well be true, but upon what basis do you ask for increased fees? One of the benefits of BIM, and in particular accurate BIM, is clash detection and avoidance. But can you really go to your client and say "pay me more and I'll reduce clashes between my designed elements and the rest of the building". What do you think they will say? They believe they are already paying you to ensure there are no clashes. As one commenter pointed out, the A/E industry has been getting away with not providing what they promise - fully coordinated design - for years.
Another common objection, was that using BIM software like Revit is more work than traditional CAD. This is just not true.
Whilst you do things in BIM software you don't do in CAD software, there are more things you don't have to do in BIM software that you do have to do in CAD software. As an example, at the request of the contractor we changed the names of some levels. In Revit this took less than a minute, just a simple text edit in one place. When we told the structural drafter, who is using CAD, he groaned as he now has to find, open, and edit every CAD file where these levels are referenced. I'm dreading telling him we are changing door frame sizes to doors in concrete walls. One parameter change for us, hours of stretching lines and redoing dimensions for him. Properly used (i.e. in the way it is designed to be used) Revit will decrease your workload. You won't get far arguing you should be paid more because your BIM software is harder or more time consuming to use (although you might get paid more if you are one of the few who can use it well).
And I can't avoid mentioning the recurring complaint about architects continually changing the design, which apparently is the bane of every engineer's working life and profit margin. Of course the cause of this really has nothing to do with BIM, or does it?
The name Revit is a portmanteau of 'Revise' and 'it'. It's original creators recognised that designing a building is a process of making changes, to optimize the building's design. And that a product that made making changes more efficient had a market. It was only later, after AutoDesk bought it, that the BIM idea took over. So Revit is software designed for making changes easy. And it does. Change one parameter and you can change the size of say, a door, across the BIM model and all drawings and schedules those doors appear in. Even dimensions on drawings change.
So architects using Revit may indeed be making changes to their model that are more vast, and doing it more often, than when they used CAD. Because they can, and because the job of architects is to optimize the design.
Revit Structure and MEP are Revit Architecture with some extra bits added. It is fundamentally the same software. So if engineers used Revit the same way architects do, they wouldn't have such a problem with design changes. They too could use their software to make vast and frequent changes with little extra work.
And who knows, they might also be able to do a better job, by optimizing the building's structural or services design. With the added bonus of annoying the architect with frequent changes!
What does Model Accurately mean?Before continuing I just want to clarify some things that some commenters were confused about.
By accuracy I mean elements being represented as geometrically accurate 3D representations at their actual location, rather than symbolic representations. They don't need to be realistic (it is best if they aren't), but they do have to represent their spatial requirements.
What I don't mean is sloppy work, where the intention is to place it accurately but that hasn't happened. All AEC consultants can be guilty of this.
Elements need to be spatially accurate during the design process, not just at the end when construction commences. How else can the architect develop the design so services fit? It amazes me when engineers think they can come in at the end of a design they have had no meaningful input in to and expect their services to fit. Or expect the owner to finance an oversized building just so their services will easily fit and make their job easier.
Another clarification is that no-one expects (except BIM evangelists) every single element to be modelled accurately. As architects and engineers we are doing design intent, not a 100% virtual representation of the finished facility. Elements that are large and have specific spatial or location requirements, like ducts, plumbing pipes to falls, light fixtures, large cable trays, do need to be modelled accurately. But elements that are small and can run anywhere, like supply pipes and cabling, don't require as much accuracy. Some elements fall in between. For example power outlets might have a required height, but the exact location along the wall is not critical. So it is not necessary to model all wall studs just so power outlets can be located to avoid them.
In a practical sense, what can be done?But it is not my intention to beat up on engineers. I feel their pain. Whilst engineers may not be able to argue for more fees, the reality is their fees probably are too low. In a free market fees paid are based on actual work performed, not what is promised or even should, in theory, be done. The other reality is this is not going to go away. Not all engineers have been forced into BIM projects yet, but eventually it will happen.
Whilst no-one can claim extra fees for better coordination, offering to provide evidence of coordination could be construed as an additional service. By evidence I mean actual clash reports, rather than just the promise that there will be no clashes. Another potential extra is providing IFC models. Both of these would involve additional work (and possibly software) to just to deliver, but the potential is there to value add. There may be other opportunities, properly used BIM software can leverage a lot of down-stream processes.
BE MORE EFFICIENT
Utilize your BIM software to improve your work practices and work flows. Unlike CAD, which is just a generic drawing package, BIM software is designed with your workflows in mind. For example Revit MEP and Revit Structure are designed to link into analysis software. Revit has a workflow for monitoring changes in linked models (like the Architect's model) called Copy/Monitor. Some commenters reported a lot of success with Copy/Monitor. Some complained it was 'too hard', but I suspect those people weren't committed to making it work. Don't fight your BIM software, use it to its full advantage.
TAKE ADVANTAGE OF COLLABORATION
There is an expectation that BIM will involve collaboration. If a client mandates BIM, you can bet they assume collaboration will occur. But what does that mean on the ground? As I have said elsewhere, my definition of collaboration is mutually beneficial cooperation. You scratch my back, and I'll scratch yours.
If the architects say they want you to accurately place power outlets, ask them to do something in return for you. I hear a lot of bitching from engineers about being dudded by architects, but when I ask them what I can do to help (as the architect) I don't get a definitive request to do anything specific, just more bitching. So don't be afraid of asking, but make sure you are explicit about what you want. Just asking the architect to not keep changing the design is not going to do you any good.
Some suggestions (from a non-engineer):
- Get some commitment that the architects model will be to a certain quality:
- existing elements will be edited rather then deleted and remade.
- objects hosted to level or floor rather than wall, floors or ceilings.
- each ceiling has its own level.
and make sure to let them know if they don't keep these commitments.
- Ask the architect to set up views in their model that you can use. If they won't do it ask if you can come into their office and set them up in their model. Might save you from having to recreate views every time you get an updated model.
- Ask the architect to use your families. Or at least start of with your families, it probably doesn't matter if they change a family's appearance as long as all the connectors and your parameters are still there.
So for all you struggling engineers out there, there is hope. Admittedly there is the hurdle of learning your BIM software, but once through that (and it does end), there are practical things you can do to lessen your load to compensate for having to model accurately.