COGO: Finding Chord, Tangent, or Radial Direction

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09-13-2021 10:40 AM
RachelFanch
New Contributor

Hello ESRI Community,

I am attempting to map an easement using coordinates in the legal description. However, there is a section of multiple curves where no chord, radial, or tangent directions are given. I've tried to Google to find a solution to no avail. 

This is the information I am given:

"Thence North 82-45-23 East, 430.99 feet to the PC of curve to the right, having a central angle of 43-11-09 and a radius of 594.15 feet."

I believe the PC stands for "Point of Curve", i.e. where the curve begins, but I'm not completely sure. 

I am trying to find either:

1: Chord Direction

2: Radial Direction

3: Tangential Direction

If someone could give me the formula or an online curve calculator to find any one of these three variables by using the central angle and radius, that would be great. 

Thanks!

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3 Replies
AmirBar-Maor
Esri Regular Contributor

@RachelFanch 

Can you please share the legal document containing the easement?

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RachelFanch
New Contributor

I can give the legal description. However, there are multiple easements with this issue so I would need a way to calculate chord, radial or tangential direction.

Legal Description:

Commencing at the SW corner of said Section 28; thence North 00-46'-42"West;

Thense North 82-45'-23"East, 430.99 feet to the PC of curve to the right, having a central angle of 43-11'-09", a radius of 594.15 feet;

Thence along said curve an arc distance of 447.83 feet, to the PC of a curve to the right having a central angle of 48-20'-50", a radius of 520.34 feet;

Thence along said curve an arc distance of 439.08 feet to the PC of a curve to the left having a central angle of 08-47'-22", a radius of 672.36 feet;

Thence along said curve an arc distance of 103.14 feet;

Thence south 49-39'-42" West non-tangentially to the last mentioned curve, 1853.50 feet;

Thence North 28-42'-28" West to the point of beginning. 

Within the legal document, there is not mention of anything that would be helpful to finding the chord, tangential, or radial direction.

Please let me know if you can help! Thanks so much. 

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JeffWard
Occasional Contributor III

Rachel,

Usually in a description, if there is no mention of a chord bearing or radial bearing it is implied that the curve is tangent to the previous course in the description. You can then enter the two parameters that you are given to finish the curve. What are you using to enter the description? Are you using the Traverse Tool? If so, you would enter * <enter> 0 <enter> 594.15 <enter> 45.1109

That is assuming your final parameter is set as the delta (central angle), you may have to change the entry unit to dms instead of dd

Jeff Ward
Summit County, Utah