Topic: Why are Civil plans 17,000 miles from the orgin?

[mjfarrell]

So, being 17,000 miles away from the origin has little or no affect on my drawings accuracy, except for maybe hatches, which can easily be remedied?  Is that correct?

Also, what benefit is it to me to be 17,000 miles away just because the civil drawings are?

Correct on first part...


The second part depends on whether you want to fiddle around with the Civil site plan NOT lining up with your version of the site plan with no added benefit to you for doing so.  And the potential issues of things not being aligned in space should you decide to use your own arbitrary coordinate system (0,0) instead of the real world.

The potential for error and the issues that arise from that; being your responsibility.
One method has no such potential for erros, the other does.

Unless you like doing work that need not be done for free; and with the added benefit of introducing errors that could be terribly expensive. I really can't say.

Here is a handy decision matrix for you:

If all you are doing is shop drawings for millwork, then none of this has any impact on you or your methods. Use (0,0)

If you are coordinating a site plan with the Civil Engineer or Surveyor, then it does. Use the real world.

[sinc]

Also, what benefit is it to me to be 17,000 miles away just because the civil drawings are?

I have to agree that it's somewhat puzzling as to WHY the State Plane coordinates are so big.  I don't think I've ever heard an explanation.

I know that when the original State Plane coordinates were created, a bunch of people got together somewhere and came up with the systems, based on their own set of concerns.  But I've never heard any details about the thought-process that went on.

In the original State Plane system, many of the coordinates were smaller.  For example, here in Colorado, the NAD27 State Plane systems use a false easting of 2,000,000, but the false northing is 0.  So while the Eastings are very large, the Northings end up being more like 300,000.  Why they chose an Origin in New Mexico (or was it Arizona?) for Colorado State Plane systems is something I don't know.  Maybe it was just to create "overlap" between zones...  No idea.

But a key reason for the different false northing/easting values is to prevent any confusion between Northing and Easting.  When using Colorado NAD27 State Plane, I always know that the numbers in the 2,000,000 range are eastings, and the numbers less than 1,000,000 are northings.  Similarly, if I'm using Colorado NAD83 State Plane, then I know that the numbers in the 3,000,000 are eastings, while the numbers around 1,500,000 are northings.  And by simply looking at the coordinates, I can immediately identify which coordinate system they are in (well, at least as long as someone doesn't use one of those nasty bastardized "Modified State Plane" sort of systems that look indistinguishable from State Plane coordinates), as well as which one is the Northing and which one is the Easting.

So I understand that much...  But I really can't say why they decided to use false northings/eastings in the millions.  Or how they chose the origins of each zone.  Maybe they also wanted to choose values that were distinct from UTM, or something...  No real idea.

[Krushert]

I still do not see why I or any other architect has to stop using 0,0 as a coordinate system all together just becuase we have to make your lives easier.  I have said it before and I will keep saying it.  It is a sense of scale.  A apartment unit in 15,000 sq ft dorm building is handled the same as a builing on a 15,000 acre.  YOu treat as a block that you loacate and rotate accordingly.  The building is just one big block (or xref).  It is not like I am setting my base point for a block of a toilet at the 0,0 coordinated of the building (tied to the State Plane or not).

 The only time I need to manuplate a site plan is to extract some basic information like where grades lines are hitting my building.  The actual rotating of a builing in a file should be done by the civil folks, that is their job.

Just my simple probably ingnorant opinion.

[sinc]

Don't really understand your post.  I also don't understand why you would do an architectural plan in State Plane.  There's nothing in that to make OUR lives any easier.

ESPECIALLY since, when it comes to Civil work, we NEVER trust Architectural drawings.  We use the Structural plans, from the Structural Engineer.  We view the Architectural plans as "the pretty drawings" that indicate how the final construction should look...  They don't really come into play at all when it comes to the Site layout.

[mjfarrell]

I would suggest that the 'site plan' be done on real world coordinates for ease of coordination between the two disciplines.
The Architects Building would be an attached reference file, done at whatever coordinate scheme they desire.
Located correctly with respect to the site plan, based off of the Surveyed property lines, which in most cases would reference State Plane.

In this fashion the Civil need not try to figure out where and or at what angle the building sits on the actual site.

[danallen]

ESPECIALLY since, when it comes to Civil work, we NEVER trust Architectural drawings.  We use the Structural plans, from the Structural Engineer.  We view the Architectural plans as "the pretty drawings" that indicate how the final construction should look...  They don't really come into play at all when it comes to the Site layout.

Funny, as an architect I never assume structural drawings to be dimensionally accurate. Structural engineers almost never spend the time to keep their drawings updated with all the minor tweaks that occur as part of architectural development.  I never xref their plans, only take structural member sizes off their drawings and draw in my plans, then check all dimensions as part of my coordination. For site layout coordination I always include the property line in my site plan and floor plans to make sure everything aligns. We are often on board before civil, sometimes even before survey, and so I locate my plans with 0,0 as the lower left corner of the property line. Often I will rotate the building plan to orthogonal to XY axis as there is no benefit in drafting all our dozens of plans in rotated UCS. My site plan is in true orientation, with the floor plan xreffed and rotated, using the property lines to match up.

[sinc]

Funny, as an architect I never assume structural drawings to be dimensionally accurate. Structural engineers almost never spend the time to keep their drawings updated with all the minor tweaks that occur as part of architectural development.

Wow...  I guess that points out the value of forums like this, where each of our collaborative disciplines can start to get an idea of how the others think...

The typical flow is that the Architect has the vision, and creates the building that is desired.  Then that data MUST be transferred to the Structural Engineer, who is responsible for making sure the whole thing doesn't collapse.  And the Structural Engineer takes into account MANY things in that assessment.  When a Structural Engineer comes up with caisson locations, etc., we as Surveyors then trust that judgement.  Locating the building correctly on the site then becomes our responsibility, but we use the Structural Engineer's calculations to layout the foundation of the building.  We DO NOT trust the Architectural drawings...  Maybe because those tend to change the most during development, and they often end up being the files that have the sloppiest linework (in our experience).  But also because details of facade, wall thicknesses, etc., no longer matter.  The architect can continue to change details like that right up until the thing is built, as long as the changes don't affect the structural integrity of the foundation.  The important thing is the foundation layout, as defined by the Structural Engineer, which we stake in the right location based on the Site Plans.  With Architectural plans, we can get into all sorts of arguments about "What exactly does 'corner of the building' mean?  Is it the internal wall structure, the facade, the foundation, something else...?"

If you work with Structural Engineers who produce drawings that are not dimensionally accurate, then I'd be worried....

[Birdy]

ESPECIALLY since, when it comes to Civil work, we NEVER trust Architectural drawings.  We use the Structural plans, from the Structural Engineer.  We view the Architectural plans as "the pretty drawings" that indicate how the final construction should look...  They don't really come into play at all when it comes to the Site layout.

Funny, as an architect I never assume structural drawings to be dimensionally accurate. Structural engineers almost never spend the time to keep their drawings updated with all the minor tweaks that occur as part of architectural development.  I never xref their plans, only take structural member sizes off their drawings and draw in my plans, then check all dimensions as part of my coordination. For site layout coordination I always include the property line in my site plan and floor plans to make sure everything aligns. We are often on board before civil, sometimes even before survey, and so I locate my plans with 0,0 as the lower left corner of the property line. Often I will rotate the building plan to orthogonal to XY axis as there is no benefit in drafting all our dozens of plans in rotated UCS. My site plan is in true orientation, with the floor plan xreffed and rotated, using the property lines to match up.

heh. I never assume anyone's drawings to be dimensionally accurate. 
I burned that bridge bridge behind me long ago.

[sinc]

heh. I never assume anyone's drawings to be dimensionally accurate. 
I burned that bridge bridge behind me long ago.

Yes, you can always run into incompetence.  Never take anything for granted.  Luckily, though, most of the people we work with on a regular basis are pretty good.  So we can usually trust their work, although as Surveyors, we're often the final QA check, so we have many things we do to make sure everything gets built correctly.  But we DO have to be a lot more careful when working with "unknowns", aka people/companies we haven't really done stuff with before.

[sinc]

I would suggest that the 'site plan' be done on real world coordinates for ease of coordination between the two disciplines.
The Architects Building would be an attached reference file, done at whatever coordinate scheme they desire.
Located correctly with respect to the site plan, based off of the Surveyed property lines, which in most cases would reference State Plane.

We pretty much do this, although you can run into problems with pre-fab buildings on State Plane.  The usual problem we see is that the Engineer "forgets" (or more-likely, doesn't understand) that distances on the State Plane grid are not necessarily the ground distances.  That can really wreak havoc in some situations.

But as Surveyors, we typically reference the Structural Plans into the Site Layout.  This also accounts for the fact that the Structural Plans are usually done with UNITS=Inch, and we (as Surveyors) hate that.  But by referencing the Structural Plans into the Site Layout, we can set points in the Site Layout, and everything works fine.  I still kind of wish Structural Engineers and Architects would stop using inches, but we can deal with it.

[mjfarrell]

It isn't the Structural or Architects 'fault' that inches are a problem.
It is how autodesk has chosen to program for use with those units.
Instead of simply giving them dimension styles that read feet and inches, instead of scaling the workplane.
Not being a programmer I may be oversimplifying this, however there is no valid reason in my mind why is shouldn't have been created that way from day one.
And then we would ALL be working with the same units insdie cad, and we would all be happier for it.

[sinc]

We actually don't really have any problem with the Inches drawings...  As I said, we simply XREF them into the correct location in the Civil plans, and everything works.

We just don't like inches on general principle.   

The only thing that upsets me is those rare instances when we get Site layouts done in feet and inches, with control point coordinates given in feet and inches...  Now THAT'S annoying.  Luckily, I can only think of two times when I saw this.

[danallen]

It is how autodesk has chosen to program for use with those units.

I've heard that AutoCAD was intended for all ranges of disciplines, and given the limitations of numerical accuracy, the generic unit was intended to be flexible. For Astronomers a unit could equal a Parcel, for molecular engineers a unit could equal a nanometer.

[danallen]

Locating the building correctly on the site then becomes our responsibility, but we use the Structural Engineer's calculations to layout the foundation of the building.  We DO NOT trust the Architectural drawings...

There are lots of different ways of working, all the work I have done is design focused and as the architect I direct the location of everything in the building that I can see and locate all columns, all walls, all foundations, etc. When I work with a structural engineer who will dimension every structural element, then my job is to review and coordinate all those dimensions. I do that manually by checking prints, highlighting correct/redlining etc. I also check all the steel shop drawings for dimensions as well. Some engineers won't be bothered with updating dimensions and put all that on us.

[sinc]

There are lots of different ways of working, all the work I have done is design focused and as the architect I direct the location of everything in the building that I can see and locate all columns, all walls, all foundations, etc. When I work with a structural engineer who will dimension every structural element, then my job is to review and coordinate all those dimensions. I do that manually by checking prints, highlighting correct/redlining etc. I also check all the steel shop drawings for dimensions as well. Some engineers won't be bothered with updating dimensions and put all that on us.

That sends shivers down my spine...  You think you can trump decisions made by the Structural Engineer...?

Well, I guess as long as you haven't been sued yet....