How do I draw a curve with survey data?

I've tried the tutorial but it's not helping me that much. I'm drawing in CAD from an original As-Built blueprint.

I have the following data:

Dc

delta

T

R

L

along with several points which appear to be an origin with the following: P1 STA 1 + 10.00

http://www.cadtutor.net/tutorials/autocad/survey-data.php

Oops, I missed that you tried the tutorial, maybe you were referring to the one I linked to?

You probably just need a good explanation (& sketch) of the terms T (tangent) VPI, etc. PI is "point of intersection, it's where the 2 straight line segments intersect beyond the curve. Google "horizonal curve" and "survey" or something like that. And feel free to ask away.

I've tried the tutorial but it's not helping me that much. I'm drawing in CAD from an original As-Built blueprint.

 

I have the following data:

 

Dc

delta

T

R

L

 

along with several points which appear to be an origin with the following: P1 STA 1 + 10.00

Dc = ? could mean several things

delta = delta angle

T = tangent

R = radius

L = length of curve

PC = point of curve

PI = point of intersection (this may be your "p1"?)

PT = point of tangent

krautfed's crash course:

Going along the centerline (CL), at the PC station... draw a line perpendicular to the CL, the distance of the radius ® ... the side of the CL you draw it on is determined by "curve to the right" or "curve to the left". At the end of the line you just made, create a circle from center with the radius of ®... be sure you don't use R as diameter. Copy the perpendicular line on top of itself (there may be an easier way, but I just copy from endpoint back to the same endpoint). Now there's two perpendicular lines, so select ONE of them and rotate from center of that circle... the angle of "delta" ...be sure you are rotating correct direction. The circle you created should now have a "piece of pie"... TRIM the circle via the original perp line and the one you rotated the delta angle... it should now just be the piece of pie (not whole pie). Now draw a line perpendicular to the ROTATED line... from the end point (where endpoint and end of curve meet).

To check your work... the curve in your piece of pie should = the "L" of the data given. This should also = PT - PC. If you continued the CL straight, without curve, from first straight line and second straight line (after curve)... the "T" in your data is the distance between the intersection of those two points, and PC or PT.

If you need more help, I'll load a image or two to help.

DISCLAIMER: I don't use other methods of drawing the curves due to errors found in closing surveyor's, engineer's, attorney's, etc's work. Traveling out to the center of radius and turning delta angle has been the best way to catch calculation errors.

So what does my PC 0+30.40 or PI STA 1+50 or PT STA 2+64.40 stand for?

More specifically, what does the 2+64.60 stand for (for example)?

It's called "stationing".

PC is the point of curvature.

PI is the point of intersection.

PT is the point of tangency.

2+64.60 is a station. It is equal to 264.60'.

Stationing starts at 0+00 and usually (but not always) is done at 100' intervals. Thus you'll have stationing that reads 1+00, 2+00, 3+00, and so on.

STA 2+64.60 is 264.60' from the beginning of the alignment (STA 0+00, probably the centerline of the street). PC 0+30.40 means that a curve begins 30.40' from STA 0+00. PT STA 2+64.40 is the station where the curve ends. The curve length is 234.00' (264.40-30.40). If you draw a straight line (tangent) from 0+00 through STA 0+30.40 with a total length of 150' (STA 1+50), the end point would be the point of intersection of the 2 tangents of the curve. If you need more clarification I could provide a sketch.

Horizontal curve layout:

http://www.tpub.com/content/engineering/14070/css/14070_239.htm

STA 2+64.60 is 264.60' from the beginning of the alignment (STA 0+00, probably the centerline of the street). PC 0+30.40 means that a curve begins 30.40' from STA 0+00. PT STA 2+64.40 is the station where the curve ends. The curve length is 234.00' (264.40-30.40). If you draw a straight line (tangent) from 0+00 through STA 0+30.40 with a total length of 150' (STA 1+50), the end point would be the point of intersection of the 2 tangents of the curve. If you need more clarification I could provide a sketch.

The only problem with that is, when I measure with a scale from STA 0 + 0.0 to STA 1 + 50 it is exactly 150'

BUT

When I measure with a scale from STA 1 + 50 to STA 2 + 64.40 it is not a difference of 114.40 feet... Should I trust the bearing and distance given rather than the scaled ruler?

Thanks guys, I really appreciate all the help given up to this point

Trust the numbers and not the scaling. Paper can stretch.

Thanks guys. This has all worked out great.

Last question (for a while at least).

It looks like I have a new station to start a new street (curve) on the curve I just finished drawing. It is 1 + 57 = 0 + 0.0

How do I set up a point exactly where it is asking in CAD?

When I measure with a scale from STA 1 + 50 to STA 2 + 64.40 it is not a difference of 114.40 feet...

And it shouldn't... the distance from the PC to the PI is called the Tangent distance. If you scale from the PI to the PT, it should be this distance.

this should help finding a particular station on your alignment

;places point at specified station along a polyline, measured from start LPS 2008

(defun c:pop ()
(vl-load-com)
(setq oldosnap (getvar "osmode"))
(setvar "osmode" 0)
(command "ucs" "w")
(setvar "pdmode" 3); if your pdmode is already set to what you want, remove or comment this line
(setq ob (entsel "Select curve: "))
(setq p2 (getreal "\n Specify Distance : "))
(setq obj (vlax-ename->vla-object (car ob)))
(setq pt1 (vlax-curve-getPointAtDist Obj p2))
(command "Point" pt1)
(command "ucs" "p")
(setvar "osmode" oldosnap)
(princ)

)

Thanks guys. This has all worked out great.

 

Last question (for a while at least).

 

It looks like I have a new station to start a new street (curve) on the curve I just finished drawing. It is 1 + 57 = 0 + 0.0

 

How do I set up a point exactly where it is asking in CAD?

All that means, is the intersection... Street 2 is going to start (0+00.00) at 1+57.00 on Street 1.

Back to my crash course... you would use LENGTHEN command to shorten the curve a total of 126.6 (which is 157 - 30.4). This is the curve length and the intersection of Street 1 and Street 2...

My engineers write it as:

STREET 1 STA 1+57.00

STREET 2 STA 0+00.00