California Surveyors Forums

I am studying for my PLS exam I am a little confused (or really confused) about “witness cornersâ€￾ I have been treating them as bearing objects, set corner by record bearing and distance, but now I’m finding conflicting solutions. Attached is a problem from 1986 PLS exam problem (2). I answered “record bearing and distance from W.C.â€￾ since proportioning is a LAST RESORT. The answer I found was a proportional distance from the W.C.

1973 manual

5-17. Witness Corners
Ordinarily a witness corner established in
the original survey will fix the true point for
the corner at record bearing and distance.
Where the witness corner was placed on a line
of the survey, if no complications arise, it will
be used as control from that direction in determining
the proportionate position of the true
point. Thus the record bearing and distance
would be modified, and the witness corner
would become an angle point.

Is one method preferred over another or are both answers acceptable for the PLS exam.

Thanks

Proportioning is used as a last resort when re-establishing a lost corner. There is no lost corner in the exam problem you cite. The corner position was apparently never monumented due to the ravine (note that there is no "x" at the location).

You ask: "Is one method preferred over another or are both answers acceptable for the PLS exam?"

"Ordinarily" you would hold record bearing and distance from the found witness corner. The section of the manual you cite provides the exception to the procedure that is "ordinarily" performed. The difference being that the witness corner in the exam problem was intended to be on the section line. Also note that the record distance per the exam problem of 5.6 chains is significant.

Therefore, per the manual: "where the witness corner was placed on a line of the survey, if no complications arise, it will be used as control from that direction in determining the proportionate position of the true point. Thus the record bearing and distance would be modified, and the witness corner would become an angle point."

Thus the reason for the answer you found.

So the position of the 1/4 corner would be proportional to the measured length of the W.C. to the N.E. Section corner (5.6/45.6)x3025.80=5.63 chains

And NOT 5.6 chains (record) along the section line to establish the 1/4 corner.

You might also want to look at Section 4-15 of the Manual, that is where it talks about when and where to SET a witness corner. To quote:
"Usually only one witness corner is established, and it should be located upon one of the lines leading to a corner if a secure place within a distance of 10 chains is available. If there is no place to be found on a surveyed line within that distance, a witness corner may be located in any direction within a distance of 5 chains."
I think that is what 7702 meant about the 5.6 being significant, it was greater than 5 chains, therefore one could presume it was on line.
(By the way, this is all per the 73 manual, and most surveys you might retrace would be under different instructions/manuals, but the tests generally test on the latest manual. Of course if you were resurveying you would get the approved notes and plat, etc., etc.)

My take on Section 5-17 which you quote is:
The first sentence applies to a WC set off-line.
The second and third sentences apply to a WC set on-line.

You might be happy to note that you are not the first aspiring surveyor to be confused by that language.
Cheers and Sincere Best Wishes

Thanks for the help