Pros and Cons of Revit MEP model being a single shared model

[SMNienow340218]

Recently I have come across some controversy as to how efficient and benificial it really is to have all three disciplines shareing the same model.

Has anyone else considered splitting up the disciplines into individual models? If so what have been the benifits/issues in doing this?

Maybe something is being missed on our end that could help. Any advice?

Any feedback is appreciated. I would like to hear all of the pros and cons of keeping it as one model.

[Foxy]

Unless it is a very small project, we currently always split the disciplines and link them for coordination checks.

The first problem I have with having all of the services in one model is that unless you are doing all services within your company, you will need to set up a site office for the project. Revit server is no good as you will have red tape from the IT department regarding permissions from external companies - especially if you are a mid to large sized consultancy.

It also means that if we have a Revit resource in another state that say, specializes in Electrical, where as our strength is Mechanical and we cannot get them over to our office for a project, we cannot send that service to them to work on at the same time as we get stuck into the Mechanical services. It's all good if you have all of your top Revit guys in one place, but that hasn't been my experience so far.

We have a project starting now where the lead consultant has convinced the client that all services, including Architectural & Structural should be in the one model. Apart from the obvious speed problems with the computers having to deal with monumental files, in this situation we are clearly going to suffer from last minute Architectural & Structural changes affecting our design as we cannot use a frozen design - which we will have to fix before issuing our drawings otherwise they will look wrong making us look as if we don't know what we're doing... I have been assured that the work will be programmed so as to alleviate the possibilty of this happening, but I will believe it when I see it.

Also I'm a big fan of Navisworks for coordination and having all services in the same model makes it a more cumbersome process creating search/selection sets to run clashes between the different disciplines. This takes a little trial and error to make sure you have picked up all the elements you require. I personally like to keep things as simple as possible so as to avoid mistakes and get the job done as quickly as possible.

The main benefit I can think of for keeping your services in the one model is linking the the mechanical loads to your electrical equipment so that all changes are automatically picked up. Very handy if you use revit for your scheduling and load balancing. I don't know of too many people that utilise this capability at the moment, as with all revit calcs they are not trusted 100% just yet.

[Craig_L]

Pro:
There is no need to do co-ordination checks between models (as there are no external models)

Cons:
Element ownership can become a problem, who controls what?? And furthermore this will cause problems in the actual modelling in that someone else "owns" an element and no one else can edit that element in the model.
File size can get ridiculous, depending on project size and complexity.
File errors will hold up your ENTIRE team meaning alot of lost productivity if your file gets bugged, which can and does happen.
On a day when you are trying to issue, keeping up with an ever changing model while trying to complete documentation is next to impossible.

Consider say Design Development issue for the client, Both structures and Architecture team are madly working away to meet the deadline on said day. Architect moves and resizes a wall, simple for the architect, for the structures team this affects several documents and perhaps reo, and details. depending on where they are at - ie. impossible to keep up with changes last minute for some disciplines and this ripples down the information chain in a wave form where the person at the end of this chain will get the peak of said wave as far as impossibility to document goes

I would not suggest using a single model unless you have some really amazing and detailed discipline specific view templates set up. Each discipline uses different linetypes, and wants to see different things.
For example: I worked on an arch/struct/mech/elec single model. I am a structural drafter. Our view templates were in the infancy stage (this was back in 2009). All of my sections and details had been made to hide architectural elements (furniture, sinks, light switches, you name it) As these are all different categories I had to hide by element in EACH view. Now, day of issue arrives, architect is adding furniture, which now goes into all of my documentation and views, which quite frankly I just dont care about nor need to see and clutters and sometimes obscures my detailing. Multiply this by 20 different slab sections for a level, and you can see where this leads. To get these templates to a workable level will require massive forethought, and a BIM management team because one BIM manager will not be able to keep an eye on that for all disciplines, and keep the templates current. It's not impossible, but you're just making your life that much harder in a single model environment.

You will get much better results with a model for each discipline - BUT remember that co-ordination is king. Regular meetings are key, talk about intended upcoming changes, continue with a paper trail and consider that the Design team (architects) Should really be a week or two ahead in their documentation, the other disciplines simply wont keep up with a rapidly changing model trust me I've tried. Consider these "lead times" for each discipline in your project schedules and deadlines, because as I said this ripple wave form will get bigger and bigger down the information chain and there is no surfing a 300 foot deadline wave. Consider the big picture right at the start because I am trying to drum it in here, that this compounds as the project progresses.
Regular meetings will mean you reduce your model co-ordination errors because the changes will likely have already been made to upcoming alterations for the next model issue.

This way architects can give you a model at their "Tender" phase (which is AHEAD of the actual issue date), all other disciplines can document up to this phase, architects are continuing ahead with consultation with the client and making changes while other disciplines are catching up, and then rinse and repeat with comfortable lead times for each major issue.

As for model co-ordination goes, I set 3D views at the start to show important elements from a seperate model as a solid red and the current model as a solid blue. You can easily see in the 3D models where things do not match. And you can tell which discipline you are looking at. Example, my 3d view is filtered to show ONLY columns, I see Arch columns in red and my structural columns in blue. Now I can easily see if a red column is stuck out where no blue overlaps it, and I can select it go to plan and quickly co-ordinate the alignments.