Changing the 0' - 0" level datum to a different level

[patricks]

Having an issue with a new building that will go where an existing building is slated to be demolished. I built a model of the existing building a couple of years ago, when it was still undetermined whether the building would be demolished or not.

Now we have decided to go forward with demolition of the building, but the new building's main finish floor will be 2.0 ft. lower than the existing building's first floor. In this situation, what is the best way to change the new building finished floor from -2.0 to 0.0? We're already far along in SD's and a good bit of modeling of the new building has already been completed.

[david_peterson]

I'd go with shared coords
You can then switch between them (existing vs new). You'll need to be sure to set your level tag and spot elevations to shared vs project.
This way, you can have the existing model read the project coords with one level type and the shared with a different level type.
Of course this is assuming I'm understanding the question.

[cdatechguy]

David's method would work....(which I have done many times in the past)....as long as your not already in shared coordinates ;)

[david_peterson]

David's method would work....(which I have done many times in the past)....as long as your not already in shared coordinates ;)
And let's just say he was. Got any better suggestions you'd like to share? I'd love to hear them.

[cdatechguy]

The only other method I know is to modify the project datum...(one of the things I love in 2011)...but I think this would break the Shared Coordinate link...

Of course I could be wrong and just moving the building location in the shared coordinates would work anyway....oh...but that would change the existing part too...

[david_peterson]

Well there's your problem.
Outside of using one set of shared and one set of project coords, I don't know how one would do it with out effecting the other the existing. I guess you could link the model into another model say center to center move the link with out getting the shared coords, but I'm not sure you can do that either.
Hmmmmm Interesting problem though.

[cdatechguy]

I think this is why our other office used two separate models....

[Steve_Stafford]

What if you linked in the existing building at the higher elevation? Since it is getting demolished you only need a reference to it "briefly"? Once past that aspect of the documentation you can deal with new levels based on the new reality? Just a thought.

[patricks]

Yes this project is already in shared coordinates. The FF of the existing building is 255.0', which is reflected as such by the existing building's 1st floor level (0.0 project, 255.0 shared).

Now the new building needs to have its finished floor lower at 253.0' and so we'd like to have the 0.0 level be for the new building, with the existing building at +2.0' (the 255 elevation).

It sounds to me like I will need to move the shared elevation from 255 down to 253, and then grab all model elements, levels, and grids and move them all back up 2 feet.