I see guys with tripods and scopes on them at construction sites and other places. What exactly are they doing and how is it done? How was this accomplished prior to modern technology?
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Surveyors use a variety of techniques to ensure the accuracy of their measurements. Some of the methods they might use include:
1. Using precise measuring instruments: Surveyors use specialized tools like transits, total stations, and GPS receivers to measure angles and distances with high levels of accuracy. These instruments use lasers, light waves, or satellites to measure distances and angles, and they are typically calibrated regularly to ensure their accuracy.
2. Establishing a reference point: Surveyors often establish a reference point, such as a known monument or a previously surveyed point, from which they can take their measurements. This helps to ensure that their measurements are aligned with a known and fixed point on the earth’s surface.
3. Taking multiple measurements: Surveyors will often take multiple measurements of the same point or feature to help ensure the accuracy of their data. By averaging these measurements, they can minimize the effect of any errors or discrepancies.
4. Using error correction techniques: Surveyors may use techniques like least squares analysis to adjust for any errors in their measurements. This involves using mathematical algorithms to identify and correct for any errors in the data.
By using these and other techniques, surveyors are able to get accurate measurements and create precise maps and drawings of the land.
We collect spatial data to make maps, take measurements, calculate volumes, lay out construction sites, stake grades, and plenty more.
I use GPS most often and work in heavy construction. Once a route is picked we go out and measure each crossing, those are things like power lines, water courses, underground utilities, roads, and other various geographic features.
Once that is complete they make adjustments to the route and then we go out and mark the boundaries of the construction right of way. That includes marking trees for clearing, staking, layout for buildings, and specific building requirements like digging extra depth or special protection for the utility being constructed.
We also as-built everything so we know the exact location of everything used by the contractor. Like the job I’m on now we have every weld, bend, different type of pipe, pile, valve, protection, and support building for the project.
A large portion of surveying is done with high precision GPS instruments. My Trimble R12i will have an accurate position of under 1 cm in idea conditions, most handheld units are a few meters or more.
We use what’s called a geoid model to essentially flatten out the real world so you get flat ground distances even over steep slopes, it’s quite the impressive bit of math and engineering to come up with that kind of stuff.
Traditional surveying is the same premise just a different way of collecting the data, those use lasers now to measure a distance from your location at a known point.
So you set up on your known point then measure angles and distances, with a little bit of math you can calculate that coordinate. With those coordinates now know you can ‘traverse’ to that location and set up again.
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