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buildingSMART / IFC4.4.x-development

Development of IFC 4.4
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Proposal to clarify how cranes are classified in IfcTransportElement #8

Open Moult opened 2 years ago

Moult commented 2 years ago

Cranes are really important.

Cranes don't have an obvious classification. The closest is IfcTransportElement, perhaps using the weird enum value of "LIFTINGGEAR". Brought up here but something I struggle with very often at work.

One of the key decisions in construction is what type of crane, how many, and where. Cranes may include crawler cranes, mobile cranes, hammerhead, luffing, and probably more. I can find a domain expert to give me a list if necessary.

Option 1: Add a "CRANE" enum. Distinguish it in the enum description, especially from craneway which is more like a gantry from my understanding.

Option 2: Add a lot of crane enums. "CRAWLERCRANE" "TOWERCRANE" "MOBILECRANE". Probably get a list from a expert :)

Option 3: Add a subclass IfcCrane. After all IfcTransportElement seems to be meant for what in Australia we'd call the Vertical Transportation consultant (escalators, lifts, disabled access lifts, travellators, etc). It's a very different domain and may be preferred if IFC wants to easily capture 4D stuff. Right now, there are a whole series of stuff which just doesn't have a nice home - they exist in IfcConstructionEquipmentResource but not as actual products on site with geometry (and geometry is crucial). Stuff like hoists, scaffolding, cranes, concrete pump trucks, and hoarding.

Moult commented 2 years ago

What would be your preference @myoualid?

aothms commented 2 years ago

If we choose to facilitate this I'd indeed say it needs to be moved out a bit from the schema to not easily confuse it with the "permanent" parts of the building. Similar to VirtualElement, maybe TemporaryElement (surely there is a better name). But you don't want your generically implemented tools (quantities, building height check) to include the steel required for the crane or fail a permit because of its height exceeding the zoning limit.

Moult commented 2 years ago

Yes it makes sense to not mix it with permanent things. Is this something we have time to address for IFC4.3? If not, we can always put this on hold until after IFC4.3. It feels like a project in itself with the need of at least a few domain experts from the construction room to be involved.

aothms commented 2 years ago

I'd say on hold

TLiebich commented 2 years ago

would propose to put it on hold - adding completely new domain entities is more an issue of an IFC extension project with stakeholders and use cases, and not via a github issue

myoualid commented 2 years ago

Cranes don't have an obvious classification. The closest is IfcTransportElement, perhaps using the weird enum value of "LIFTINGGEAR". Brought up here but something I struggle with very often at work.

From the above discussions, it seems clear that IfcTransportElement is only meant for permanent equipment in the building -

In the mean time, maybe we can do something about the Semantic definition of IfcConstructionEquipmentResource :

"Examples of relevant subtypes of IfcProduct are IfcTransportElement, IfcDiscreteAccessory, or IfcProxy (for particular cases where more precise usage details are not available)"

Sure - if, and only if, the Product which is permanent in the building is used temporarily for logistics during construction. Common scenarios would be an elevator in a building (or a crane in a factory) that is put in service before Project Handover.