NAD83 compared to UTM Zone North? 1

[delagina]

I was going to ask this in survey but that forum is not active.

I'm looking at a goby grading plan and see the coordinates are based on "UTM Zone 11 North NAD83" I understand US is divided in different zones and we are located north but I'm confused with UTM and NAD83 together. I thought they are different.

 

[delagina]

How does UTM Zone "x" North compare with state plane coordinates?

 

[TLHS]

UTM is a flat local projection. NAD83, in this case, is what it's projected from. The earth isn't a sphere and isn't really an ellipsoid. There are many different systems that have slightly different assumptions regarding what shape to treat the earth as and how to map latitude and longitude to them. NAD83 is one of them.

Latitude and Longitude are used to define UTM. So UTM is mapped on top of the NAD83 model. UTM mapped on top of NAD83 will be different than UTM mapped on top of NAD27 or something else.

 

[delagina]

Thanks TLHS, how would I know if the topo I got is UTM on NAD83? Is this something I should always asked the surveyor or its shown somewhere in the topo file?

Aside from UTM what other "common" projection topo is based on here in the US for the purpose of site grading?

 

[dik]

TLHS... an oblate spheroid.

Dik

 

[delagina]

How would I know if the topo I got from survey is UTM or State Plane Coordinate? I've seen both used. I can ask the surveyor but want to ask if I can figure that out without asking the surveyor based of the topo dwg cad file I received.

I'm only seeing point coordinates in my topo and nothing whether it's UTM or state plane coordinate but maybe it's in the properties of the coordinates. I'm using Civil3d.