Can I trust my handheld GPS
“With great power comes great responsibility” Quote from the French Revolution or Peter Parker of Spider -man fame
We have more computing power in our pocket now than the Apollo astronauts had to get to the Moon and back. It is great stuff, but please use it with caution!
Please let me tell you a little story. I was working on a survey for a gentleman near Birnamwood, WI. It is a 40 Acre parcel where we were completing a boundary survey. I had all the other corners set and was about to traverse back to the NE corner of the 40 Acres. The owner said to me “you don’t have to go back to that corner, it’s already set”. In completing my pre-survey research, I hadn’t seen any mention of a map or evidence of how that corner would have been placed. I also know from experience that there was a surveyor that worked in the area (and did very good work) in the early part of the 20th Century. That time period was prior to any rules requiring maps to be filed in a public repository.
So I thought, I would traverse back to the corner and see what I would find. I found a 1” iron pipe in the ground marking the property corner with a 3/8” fiberglass rod sticking out of it, rising 3 feet or so in the air. It looked great! The only problem was that the pipe was 35 feet from the Northeast corner of the 40 Acre parcel. There are several problems with this. The paramount issue is adverse possession. After a length of time (generally 20 years) if the neghbor’s had both been treating that marker as the corner and had been cutting trails and cutting wood and maintaining lines to that corner, their actions (or inaction) can lead to potential claims on the property. This is commonly known as adverse possession. Adverse possession is a complex legal topic which requires a court of law to wade through.
For this story, suffice it to say that the landowner was surprised that the marker was in the wrong location. It turns out, his neighbor had used a handheld phone, or other GPS device, to set an iron pipe at what he thought to be the property corner. If you find an iron pipe in the woods you can’t assume that it was set by a Land Surveyor or assume that it is an accurate representation of your property line. The best evidence that the monument was set by a Land Surveyor would be to find an associated map (Plat of Survey, Certified Survey Map or Subdivision Plat) and try and check the location of the monument that you find against a record distance from another monument on your property or a neighbor’s property. Don’t assume that a monument that you find in the woods, or your back yard is accurate. In Wisconsin, Land Surveyor’s are required to file a map showing that they set property corners. The map will also denote what type of monument was set at the corner. These maps can be found in the County Surveyor’s office or the Register of Deeds Office depending on the type of map.
So, why was the iron pipe not in the correct location? There are many possibilities. Maybe the app that the person was using to set the corner had lines which were not accurate. Maybe the GPS device was of poor quality or had a poor signal. Even GPS devices that professionals use that cost upwards of $20,000 don’t work accurately everywhere. Excessive tree cover and poor cell signal are two of the limiting factors.
I would be happy to discuss the above information with anyone.
