I was going through my yearly cram training for CEUs at a local Society Of Surveyors 8 hr seminar a year or so ago.?ÿ They went over a section about GNSS, RTK, VRS, etc.?ÿ ?ÿThen the instructor said something that divided the classroom of about 70 surveyors.?ÿ He said that you cannot do a boundary survey using only GNSS.?ÿ (This is in NC)?ÿ
If that is so, where does this fit in? https://www.ncbels.org/wp-content/uploads/2019/03/Positional-Tie-Reporting-Policy-07-19-2019.pdf
Firestix,
The question is when did you take the seminar?.....The board changed our certification (I forgot the exact date) to include positional accuracy as well as loop closure. My feelings would be that prior to the certification change, that the survey would require ground run control. Now that positional accuracy is included in the certification you can also include GNSS surveys as long as you meet the accuracy requirements. The report is also telling you how to label your ties...If you used a CORS tie in your computations, the cors information was supposed to be on the face of the map. Also, if you are using OPUS or RTN to survey, you are supposed to note the source used, coordinates, convergence, scale factor, etc.
As @terminus-nc said, it sort of depends on your state.
Washington has a section of administrative code that lays out minimums for linear and angular closures of field traverses for land boundary surveys, as well as a section which sets out minimum relative accuracy standards for "when positioning techniques used in a land boundary survey are not amenable to analysis with standards in WAC 332-130-090." 0.07 USFt + 200 PPM @ 95% confidence.
In other words, satellite positioning methods are allowed for boundaries. And generally speaking, they should be, because a correctly performed GNSS survey in conditions appropriate for that survey will be every bit as good as a field traverse for the same parcel.
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But, as to whether the average GNSS survey is being performed correctly? That's a whole different question...and why I have a love/hate relationship with the local real-time network.
