Surveyors units (Arcs)

on a typical arc on my surveyors drawing I have 3 types of measurements.... one is: a=199.086 the second is: Arc=189.13 and the third is Rc=200.00

with those three sets of information can anyone instruct me in great detail (step by step, command by command) as to how I would draw that arc (and subsiquently many other arcs on a site plan that I have)

Thanks in advanced

 

You have another whole thread going on in the 2004 group.... :-(

As "Tripp" responded in the other thread..The information you have is not sufficent to construct an arc, unless you can identify "a", "Arc", and "Rc".

If "Rc" is the radius, and one of the other two is the arc length, then you can caluculate the "Delta" - or possible make another calculation based on the following formulas.

D=L/R
R=L/D
L=R*D
(where D is Delta, L = arc length, and R = radius in radians)

Once you identify what you have, use the ARC command and follow the prompts -or- do it the old fashioned way, construct some temporary linework that will define the begining point (PC), radius point (RP) and end point (PT), then draw your arc through these 3 points.

 

D=L/R
Duh.....
Obviously not radius in radians, but "Delta" (or included angle) in radians.

 

Ask the surveyor. Make sure you know exactly what the three values are referring to.

 

By asking this question, it appears to me that he should not be trying to do
something that he has have no idea.
By investigating the "numbers" in question, it appears that one of them has
to be incorrect.


| Ask the surveyor. Make sure you know exactly what the three values are
referring to.

 

Grump:

I gave your numbers a test, as I am familiar with how the language was in old timey deeds written for railroads.

My thought is that the RC is equal to the radai for the curve in whole feet.

The 189 number represents the chord for the curve.
The 199 number represents the length of the arc for that same curve.

As you know, all curves are assumed to be perpendicular to the last course cited in a deed. Thus to illustrate, construct a triangle with two sides being 200, and the third being 189.13 and you have the basis for your curve. The center being where the two ends of the 200 lengths meet.

Wm.

 

As you know, all curves are assumed to be perpendicular to the last course
cited in a deed.

That is a mighty big assumption I would be a little unwilling to make. It
is my experience that most, not all but most, curves are tangent to the
preceding course, but there is a substantial number that are not.

What about a sideline intersecting a highway curve, that certainly isn't
going to be tangent, what about the 'cusp' (granted a rarity these days) of
a curve, again not tangent. There are just to many contrary situations to
make that blanket statement about tangency.

Jon Schmidt
Senior Surveyor
Nelson & Pope

(remove the obvious for emails)

 

While I would tend to try to make the curves tangent to begin with, you are
right, not all curves are tangent. The closure of the lot ( how close the
last calculated end point comes to the beginning point for those non
surveyors) will be a good test.

GrumpyChick

If you only have a boundary description with no other evidence and more that
one curve in the description your probably better off trying to make the
curve tangent to begin with. If there is only one curve. work you way around
from one end to the other. They you can fit the curve in tangentially and
see if it fits. If not you may have to force it in "Broken Back"
(Nontangentially)

Allen