Tag Archives: surveying

Surveying is Spelled with an ‘S’ Right?

Working on the land led me back to surveying, dragging me back in inch by inch. We’re about to start thinning our timber stands and having the property lines neatly mapped in my head doesn’t help a logger. I told our forester “I can mark our boundaries, no problem”. Afterall, I walk the property lines every year, marking and GPSing the monuments and corners, so how much time could it take?

It was easy going where the corners were close, but the longer courses (>1000′) were hard to mark with the rolling topography in dense woods limiting the line of sight to 20′ and sometimes less. “No problem”, I thought, I’ll just pull out a handy pocket transit and back it up with a surveyor’s compass and GPS. After all, I had the plat map with the bearings and I could even pull out the theodolite if I have to. Doing this without a rod man would take a little more time running back and forth, but all I needed was a straight line between two pins.

Several days of work into this and I’m triple checking my work. Why? Well, because things don’t jive. Our neighbor’s logging operations seem to be offset (both ways) to our property lines. My courses don’t intersect as well as I want them to, no matter how many times I run them and evidence of recent surveys don’t make sense (their lines aren’t even cut straight.)

I thought that using multiple lines of evidence (old fence lines, surveyor’s compass, transit, old flagging, overgrown roads, GPS, sighting by naked eye, and dead-reckoning) would tease out the real boundaries but everything seems slightly and equally off. Since I’m not getting the degree of consensus I wanted, I’m taking it a step further. I’m going to determine the change in magnetic declination from the original survey (circa 1992), using COGO (coordinate geometry) in ArcGIS, and then applying correction factor to all 59 bearings. Then I’m going back out there to see if things make more sense, but first I have to learn ArcGIS COGO and surveying again. What’s the difference between an azimuth and a bearing again? Oh man yeah, I’ll be starting from scratch and COGO in ArcGIS? Yikes, I’m scared….