How do surveyors determine where a property line is at when they get to a new property? Do they just use landmarks like trees and drive ways to determine the property line? What’s the difference between me taking a few wooden stakes and orange flags and just saying that’s my property line opposed to an official surveyor?
I imagine there is a process they go through to determine the exact measurements of the property but what is it?
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The surveyor has something called a “plat” or “cadastral map” that shows exactly where all the property lines are. He uses that map to determine where the lines are on the actual ground, and mark them.
There are little land marks in the street that you can measure from. On the deed or what ever it will be like from x 15 feet north, 20 south etc
The funky optical devices (usually yellow) on the tripods are called theodolites** – basically they measure distance and angles from where they are very accurately. And it can use GPS as a backup location assist.
So there will be some known spot. Maybe a manhole cover for the sewer. The city knows exactly where that is in relation to… well whatever they use as an origin for measurement. City hall, who knows. The location of that manhole is know to within the inch. From there they use and move the theodolyte and the stick (for the other end of the distance being measured) to mark out where exactly the boundary of your property is according to the map of your street or development on file. Street and subdevelopment plans, accurately plotting every plot and street and utility line have been filed somewhere at city hall and are required before any work can get done.
The reason the city keeps track is because they have to. Whups, we need to move this sewer. Can we move it a foot north? Nope, it’ll run through /u/zeek1999’s lot so now we have to get his permission. And for knowing where stuff is for safety (call before you dig etc.)
** so they know where they are right? Or you tell it where it is. The manhole cover lets say. The other surveyor goes over to some place and holds the stick – the theodolite shoots a pulse of light, it bounces off the stick – using the delay, it measures distance. Meanwhile you’ve calibrated the device to a particular origin bearing and very accurate angle measurement is built in. So if you know a distance and the angles from some reference bearing you can accurately measure anywhere in sight from your known reference point.
There is a system of surveyor benchmark monuments. A legal description of a property contains something called a metes and bounds description; an accurate description of the boundaries of said property. It starts with the “point of beginning” and proceeds around the property back to the same spot. The location of the point of beginning is recorded relative to a survey monument. Also, property corners are often marked with an iron rod driven into the ground. You can find them with a metal detector. These days, properties are often based off of GPS coordinates. The GPS device used by land surveyors is much more accurate than what’s in your phone. Sometimes they utilize repeater stations on the ground in addition to satellite signals to improve accuracy.
He has the map on record, which usually has coordinates. He uses his equipment to mark out the coordinates using accurate GPS and measuring against other mapped objects. This gets harder for very old properties with lines defined in different ways. People near state borders have suddenly found themselves living in another state after newer surveys with more accurate modern technology moved the border. The surveyors way back when thought he was on the other side of the border, turns out he wasn’t.
Indian here. I can answer this based on the experience I’ve collected with my dad surveying and marking plots.
Here in India, any land is categorised between two types
Agricultural and Non Agricultural
So talking about Property lines, The Agricultural Land is usually broken down into various Plots by a surveyor and its printed on a map.
Stone Markings at each corner of a plot are kept when the Agricultural Land is converted into a Non Agricultural Land.
This is what happened in the past.
Now if you have acquired a property, by law you have to immediately set up a boundary wall around it.
Let’s say you haven’t built a boundary wall around it and now you’re stuck in a huge open field with nothing to rely on.
That’s where those Stone Markings come in.
The Map submitted by the surveyor provides you different sizes of plots and the lengths of the road surrounding the area.
So if you happen to know the distance between the road and the point your property line starts. You can actually find your property lines using basic surveying methods.
And if you’re not so unlucky and someone has already built a boundary or a house near your property
You can always take a reference from that Property.
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