Expert: Bob - 9/20/2007

Question
I am working on a plant and we don't use xref i am trying to start. We have many pipe racks and roads on one dwg and i'd like to put the roads on one dwg and xref it in to other dwgs but i need the roads to break behind the pipe racks and other things we may be showing, and the roads may change as updates come in. So how do i keep the breaks when a new updated road dwg comes in.

Answer
Hi--- as you have gathered, when you have underlays that can change, xrefs are the way to go.
---although what you are doing sounds like you might check into AutoCAD MEP, Revit MEP. or another program that is meant for piping and so on.
The "vertical products" have some more features. For instance, Autodesk Architecture, which I use, has a break mark with a wipeout attached. O know that the MEP products will break ducts or pipes behind others if you ask them to, but I doubt them will break a road.
Of course, you cant xref in a changed road and have it automatically break behind the pipe racks, since the road would have to contain the intelligence to do that.  You could draw a wipeout behind the pipes, so that whatever crossed under them would not be seen (tricky, but do-able)
Not my field, so I suggest you look for Autodesk Discussion Groups that relate to your field and ask how others handle this.
Again, your notion that the road should be an xref is correct, unless there is a program meant to handle that.

BOB