Whenever a road is built or worked on, a worker is looking through one of those telescopes on a tripod. I assume they are surveying or measuring straightness. please?
In: Technology
They are called total stations. They measure angles and distances from point within line of sight of the total station.
Super simple use example. You have a known point and then you use to total station to measure other points. When building roads you need to know where and how high the road is supposed to be based on blueprints at each point.
It could be a [transit level](https://www.johnsonlevel.com/News/TransitLevelsAllAboutTran) (not the best, it’s an add). I think they’re meauring elevation. Whichever code they are working to probably specifies thickness of layers and grade etc. That is just a guess, I do not work in civil construction.
They’re surveying. The “telescope on a tripod” is probably a level.
A level is used to measure elevation. You look through it at a rod, and the height your eyes hit the rod at tells you how much higher or lower the ground at the rod is, compared to where you are standing.
Levels are pretty old school, but they still see a lot of use because they’re cheap and easy to use. Modern surveyors use a device called a total station, which looks like a big camera on a tripod. It’s operated remotely by a surveyor with a reflector on a stick. The device rotates to line up with the reflector, and then sends out a signal. It can figure out the distance between itself and the reflector, as well as the elevation difference. And it automatically updates a database in a computer with that data.
They are measuring distances in three dimensions, up and down, near and far, and side to side. Roads have to conform to certain standards, which are determined by engineers. The standards determine things like how hard it is for a vehicle to go uphill (grade) and how the road sheds water (to make it safe for driving.) The measurements that the surveyors make help the road builders to keep their construction in conformance with the standards.
I’ll give the old school answer. It’s a bit different now with gps and such.
Theyre making sure the road is exactly where they want and curves the way it’s supposed to.
They start at some place that is marked on a map as being some exact latitude, longitude, and elevation. (It’ll be a little metal circle plate on the ground. They’re all over the place.)
They set that device there, and someone with a post goes to another marker.
They look thru the telescope and point it til the cross hairs in the scope line up with the post. The map says what the compass angle between the markers is, so they set a dial on the telescope base to match.
Now, to find the exact position of another point, for instance some point on the road being built, they move the post there. Now they turn the telescope to line up with the new post. They can read the correct compass direction off the dial. They can tell if the new location is higher or lower by the height on the post at the cross hairs (that’s why the posts have a checker pattern). They get the distance using a rangefinder. They do math to figure out the location.
Newer systems are mostly automated and computerized and include GPS tom improve accuracy.
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