Drawing a Property Line Arc Correctly

[Anonymous]

May I please have help to draw a property line arc with curve, delta, tan, rad, and total arc information?

[dbroad · Accepted solution]

See this link for information on horizontal curves:

https://www.esf.edu/for/germain/Horizontal%20Curve%20Formulae.pdf 

If the arc is between two straight sections I prefer to draw the previous property line as a polyline, using distance and bearing.  Then I choose "Arc" and enter the relative chord distance and bearing.  Then switch back to "Line" and continue entering the next straight line. 

You can also draw the arc's chord first as a line.  Then use the arc command <pick start>, choose "End", <pick end>, choose "Radius" and then enter the radius.  The delta will be handled automatically and the arclength should be correct.  Since AutoCAD always draws the arc counter clockwise, you may have to mirror the arc.  I usually draw the arc by picking the endpoint of the chord first.

Before starting, set the units up correctly, including setting linear units to decimal feet and angular units to survey units.

[Anonymous]

Hello:

The information I have is as follows, so I don't think I have coordinates:

Delta = 90°11'

Tan = 30'

Rad = 29.90'

Tl Arc = 47.05'

Argh!

This information is not from a survey, but from the plat.  I haven't worked on site plans in a long time, which is the reason I need help with this.  Because I couldn't remember the arc part, I began with all the straight lines.  Now I need to close the site with the arc.  I know I cannot just draw a circle with the radius, then touch the endpoints of each of the two straight lines with the circle and be correct.  It could not possibly be that simple and still be correct.  Or, could it?  If that is so, then a person wouldn't need the TAN or the Delta, right?  Or, could I draw the circle at the given radius, the draw a line from center of circle to "twelve o'clock" then rotate/copy that line around from "twelve o'clock" the distance of the arc and be done.  Okay, I am not following this at all.  Is that because I don't have enough information?  Good Grief!

[Anonymous]

Sorry, but the link you posted did not work for me.

[Anonymous]

Hello:

I did find a calculator online that was of some help.  I'm so old that I don't think of looking for some calculator to do the work for me.  I thought I had  to use my wits to figure this out with a formula.  Times are a-changing, right?  And will continue to do so with or without me.  Ugh.  Thank you for your help!

[Anonymous]

Thank you so much for your direction regarding the issue I had with drawing a horizontal curve. I really appreciate the help!

[dbroad · Accepted solution]

The curve data posted isn't enough to create the arc at a specific orientation.  The plat will probably have the chord length and direction.  If you already have drawn the adjacent property lines, arcs are usually tangent to the adjacent lines so you can just use the fillet command with the given radius.

[Anonymous · Accepted solution]

Yes, that did cross my mind, but was unsure if that would be precise enough. Now, hearing that from you I will believe it. Thank you for your direction. I appreciate your help!