25-30 years ago I did some surveying for a boundary. The survey was started on a NGS point using NAD27 coordinates. The AZ mark was backsighted and then traverses headed north and west from the point which was near the SE corner of the "parcel". From there I ended up laying out control and checking back into myself adjusting traverses and building a complicated set of figures as the survey went north and west.
Now I'm faced with going back up and adding an additional 7 miles of line inside the boundary. But of course I'm not using a 301B but R8s.
So, I established a coordinate set using the NGS point datasheet, then guessing at a scale and scaling around the point. After setting onsite Friday I located a few corners and laid out a mile and half of line. Taking the data back and fixing to the local CORS point I "checkin" N89-30E, 0.62'.
I wasn't expecting that, this point is 45000' northwest of the starting point.
I also had to change the NGS datasheet coordinate to the original NAD27 coordinate in my file, not sure if that would have made it better or worse.
Nice to see the old coordinate system can work that well with new GPS control.
Nice. But if you had all that 25-30 year old traverse data in StarNet format you would be able to hit a few points with GPS, update your "held" positions, and rerun the whole schmeer to the current datum, duck soup. Your old data would fit to the new vectors well. Obviously that 0.62' is excellent for 45000 feet of traverse, but the GPS is even better over those lengths, and I hate to leave those things be when I don't have to.
I wasn't using Star-net then, I believe I acquired it about 95 or 96. Sometime about then.
But I'm not adjusting anything for this project, simply finding the corners running line between them. I'm amazed how close I am considering it's an office projection with a guessed Scale factor around a beginning point that I'm not occupying for this. Yesterday I tied a number of caps, usually missing something like .25' x .35', I even poked one up with a neighbor looking on it was a couple of tenths underground now. Didn't need the pin finder just the point of my rod.?ÿ
The old plats will remain record, no adjustment needed.?ÿ
