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Electronic Total Station Leveling Best Practices
350RocketMike replied 1 year, 5 months ago 22 Members · 38 Replies
In this scenario I’m talking specifically from a machine control standpoint. If we’re paving a roadway, in this case an interstate road, we would generally have 3-4 total stations set up in the median spaced 300-350′ apart, each resectioned in using the surrounding control. The total stations are communicating via radio to radios set up on our concrete paving machine to a computer and sighted on prisms on both sides of the paving machine. Once the paving machine moves out of range of the furthest back total station that total station is leap-frogged ahead of the others. Our issue in this scenario is that there is a limited amount of space in which to set up the total stations since were are paving on one side and there is live traffic on the other side. Generally we have maybe 15′ – 20′ between the paving machine and the total station. When a total station gets bumped off balance it’s usually from a finishing tool (float with a 12′ handle). It’s not a regular occurrence because most of the worker know to be mindful of the equipment, but every once and a while someone will get complacent and will forget to look out for a total station.
Since I always set SOMETHING in the ground- whether a hub. nail, RR spike, etc.- I would re-level, re-center over the point, and re-shoot one of the BS’s. Even if I know the point won’t last the remainder of the day, it gets set in the ground.
The previous party chief- long since retired- almost never set anything for temp points, whereas I like to leave my footsteps re-traceable just in case.
The only superior evidence is that which you haven’t yet found.DaveJay, post: 452232, member: 12592 wrote: In this scenario I’m talking specifically from a machine control standpoint. If we’re paving a roadway, in this case an interstate road, we would generally have 3-4 total stations set up in the median spaced 300-350′ apart, each resectioned in using the surrounding control. The total stations are communicating via radio to radios set up on our concrete paving machine to a computer and sighted on prisms on both sides of the paving machine. Once the paving machine moves out of range of the furthest back total station that total station is leap-frogged ahead of the others. Our issue in this scenario is that there is a limited amount of space in which to set up the total stations since were are paving on one side and there is live traffic on the other side. Generally we have maybe 15′ – 20′ between the paving machine and the total station. When a total station gets bumped off balance it’s usually from a finishing tool (float with a 12′ handle). It’s not a regular occurrence because most of the worker know to be mindful of the equipment, but every once and a while someone will get complacent and will forget to look out for a total station.
This is precision work. Your worst nightmare would be one of the crew “helping” you by relevelling it.
I’ve even known pegs/nails disturbed but “don’t worry we put it back in exactly the same place”
squowse, post: 452242, member: 7109 wrote: This is precision work. Your worst nightmare would be one of the crew “helping” you by relevelling it.
I’ve even known pegs/nails disturbed but “don’t worry we put it back in exactly the same place”
Absolutely agree, I appreciate the discussion going on too.
DaveJay, post: 452232, member: 12592 wrote: In this scenario I’m talking specifically from a machine control standpoint. If we’re paving a roadway, in this case an interstate road, we would generally have 3-4 total stations set up in the median spaced 300-350′ apart, each resectioned in using the surrounding control. The total stations are communicating via radio to radios set up on our concrete paving machine to a computer and sighted on prisms on both sides of the paving machine. Once the paving machine moves out of range of the furthest back total station that total station is leap-frogged ahead of the others. Our issue in this scenario is that there is a limited amount of space in which to set up the total stations since were are paving on one side and there is live traffic on the other side. Generally we have maybe 15′ – 20′ between the paving machine and the total station. When a total station gets bumped off balance it’s usually from a finishing tool (float with a 12′ handle). It’s not a regular occurrence because most of the worker know to be mindful of the equipment, but every once and a while someone will get complacent and will forget to look out for a total station.
I’m curious if the control has prism stations on tripods. You must have to be ever so careful with the measure up from the nail.
Maybe there are other measures you use to get accurate elevations?squowse, post: 452244, member: 7109 wrote: I’m curious if the control has prism stations on tripods. You must have to be ever so careful with the measure up from the nail.
Maybe there are other measures you use to get accurate elevations?We do set prism poles on tripods over the control points to do the resection, usually a three point resection. The total station itself is not set up on a point.
DaveJay, post: 452246, member: 12592 wrote: We do set prism poles on tripods over the control points to do the resection, usually a three point resection. The total station itself is not set up on a point.
Ah prism poles, so you get a fixed target height. Makes sense when bearing down on the mm.
I usually take a backsight after the resection is solved (natural or otherwise). That way if the instrument has to be re-leveled I have something to check. This is the same reason I set a point. (Even if it’s temporary why not stick a mag nail in the dirt so you know where you were set up…..if you don’t want to waste a mag nail you need to charge more.)
I prefer to set up over a point. It gives me more options.
I do utilize resections. However, I do not depend on them. If I just need to set-up quick I won’t leave a mark.
Especially in situations when you are traversing. It can be a future back-sight, thus a way to check elevation.As for eliminating centering and elevation errors. I can’t see it, unless you have tons of redundancy.
Resections depend on solid control, in my humble opinion a two point resection can work but it also hides any error. It also depends highly on the instruments edm accuracy. I also find it easier to catch elevation errors by setting up over control than resecting and checking control.I’d rather have that set up over a point. For the sake of time and having a check. It’s more deliberate in my eyes. You may not know exactly where that point is from one resection but you have an intention on setting up over it. Unlike being less deliberate and setting up on a different point.
I like having a point if you are still at a point and have dislevelment. You can re-level and take on a couple backsights without doing a full resection.
It’s also allows you to correct for curvature and refraction properly when traversing. If I never setup over a point I basically am trying to estimate the refraction constant. Which at the end of the day is less accurate elevation wise.
I’d rather accept some centering or measure up error then having to deal more with EDM and refraction error. Horizontally sometimes all you need is the angles to get a good solution. If your plummet is in good order, I see no reason not to take the time to setup over a point.
Hmm??perhaps start over with a new resection? I think if I were doing layout It would be safer to throw a traverse or resection over a hub and throw another point where I can keep using the same setup for that same layout. I was always taught to use the same setup each time to get repeatable and consistent results when doing layout otherwise you risk having error.
I’ve been using resection routinely for several years now. In the hundreds of such setups I’ve done perhaps less than a half dozen have settled or been bumped and had to be relevelled. One of the advantages of resection is that you can readily set up in spots that are stable and safe from interference, as well as convenient to the work, rather than where the control happens to be.
As far as recovering from a “bump” – it depends on the magnitude of the bump and the nature of the work at hand. If the displacement is very minimal and the precision requirements of the work is low you can probably get away with resetting a backsight after relevelling. Never to simply relevel and carry on. Nevertheless my instructions to crews would always be to redo the resection to be safe.
@norman-oklahoma I’ve been using resection routinely for several years now. In the hundreds of such setups I’ve done perhaps less than a half dozen have settled or been bumped and had to be relevelled. One of the advantages of resection is that you can readily set up in spots that are stable and safe from interference, as well as convenient to the work, rather than where the control happens to be.
This is the way. The whole point of resecting is that you can observe from the best possible position.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil PostmanTo continue off on this tangent (since I think the OPs question has been answered) – If you’re pulling elevations, I don’t know how you could not put a resection hub down. Do you generally not use the RS point to backsight or check in to?
ddI was always taught to use the same setup each time to get repeatable and consistent results when doing layout otherwise you risk having error.
Oh, there’s still going to be error no matter what. Centering error, measure-up error, EDM, angular, backsight, plus the relative error that already exists in the coordinates of those two points being used. The latter is what will really burn you if you’re not careful.
A single setup for the entire duration of the project is great if you can do that, but it does require one to be able to see everything from the same occupy/backsight every time, and assumes that there will be no obstructions and that those two points will be stable to boot.
Assuming all control points are locked down to the same level of relative accuracy, a 3+ point resection, using angles & distances, with a zero station height will be tighter (relative to the entire control network) than a simple two-point baseline. A proper control network doesn’t force you to hang all your work off two points.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil PostmanI would probably resect more often than I do if it weren’t for the fact that on multiple occasions SurvCE v5 had failed to solve what should have been a very strong resection (usually 3+ points in a tight network). I’ve never documented this due to the need to get work done, but it’s very frustration to take D+R observations on a bunch of points only to be told that no solution is possible. It doesn’t happen often, but it has happened enough times to make me hesitate to resect when I have other almost-as-convenient options.
Oh, there’s still going to be error no matter what.
Yes, I agree. No matter what there is always error, it??s implementing good field practices that minimize error building. It??s harder to repeat a resection and get consistent results each time that a regular two point setup(mainly rotational error).
Yeah I usually always set a nail even for a resection, especially in winter here, frost melting can make the ts go off level in a short amount of time. If I have the nail I can just re level, recenter and backsight the furthest resection point used in the resection and then check. Without the nail I would probably be walking to 4 or more points to redo the resection.
Besides all of those things if you’re laying out like 10+ houses in a row, the backsight could be right in front of the last few lots. It’s not a great idea to layout those buildings from the setup point way down the road, when you can setup on the much closer point.
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