Hie guys, I have a challenge here. I have been placed on a new site, working with another surveyor from a different company. We all used same initial control points and transferred to local control on the site. He is working on the deck and i am working on the foundation. One of the days he wasn't around and i was asked to put some marks on the decks for grid lines. When the other surveyor came back he checked my points and they were varying from his by 15mm on the X and 21mm on the Y consistently on all the points. I concluded the problem must be with the control points he had transferred to or i had transferred to. The site manager wasn't happy about it and doesn't care who is right or wrong. he wants us to harmonize our control. how do we do that considering that i have been using the same control for the foundation whilst he has been using his own for the decks. Or preferably is there any other way of dealing with such a scenario. Most importantly, the tolerance for the job is -5mm to +10mm.
This Content Originally Published by a land surveyor to Land Surveyors United Network
Have you checked you used the correct prism constants?
Have you checked that you haven't transposed some of the coords?
Maybe both you guys need to re-establish the main site control.
Can you get around it on this building by adopting his control from now on, the tolerances on the foundations should permit this.
Use Geolab to adjust the points. The other issue is what datum you are in? Are you using grid coordinates or ground coordinates?
We have this all the time at my survey office here in Canada
Hi Killivien, This can happen on a construction site, it has happen to me, if you two are using the same coordinates system you can compare other points before checking your equipment , it maybe something went wrong that day. work with him and test both guns on a side ,angle side triangle and see if both are the same under the same conditions, this will give you a test of both equipment it maybe a rod is out, either way
this will test dist and angle of each gun and compare calculated dist to shot dist of the missing side this will check your gun and his, also swap rods on a dist check. I have found that working with someone is better than not , but this is a two way street. Good luck
Killivien, If the both of you use mixed tribrach and rods make sure they are the same dist. in reason of each other, is this error all base on total sta. Data, that is what i was assuming . this could also be accumulated error how many setup was involved to set or check these points.
Create the Triangle with new coordinates, both of you should have a very close triangle data, about 200 meters are150 meters dist, the triangle will check your equipment do a side, angle side, then shoot the dist. on all the points if you like check all three angles, they should match in reason of the calculated triangle if there is anything wrong it will show up here.then you will know where the error is, and if something needs to be fixed. also is there heavy vibration going on around the survey, there can be a lot reason for this. First make sure you both turn the same angles and shoot the same dist. then go from there.
Hi Sithole. Did you survey in all the point you set out? I would say take all his point surveyed and yours put it into modelmaker and overlay it in 2 different projects. Then in Project 3 put the design point and check whos is over lapping the most using the control points as the main point of transformation.
I am confused, maybe i ASSuME something, I was under the impression that this survey was in reference to a total station survey, and these points were to a grid layout to a building.SO please someone explain i am lost. Where is the GPS ???, get the hammer out again.
Good Day Mr. Billy
I remember you helped me before with a great reply.
Most of projects managers try to safe cost more than getting accurate job.
so like me i forgot working with GPS. (only when project start)
I think this problem in the prism constant, or he should check the other surveyor grid.
Hi Ahmed, Good to here from you,hope you are do well. No matter what the problem is these two have to work with each other and get on the same page ,if they are using the same coors this is great they can compare northing and easting or what every they are using,if they came off the same controls with the same values, then they should be in reason of each other.If they can not work together to solve this, then who is correct.People around the world do things in different ways,so what i think and what i tell you i would do may not be what someone else see's as a solution to the problem. When all else fails go back to the basic,check angles and dist.sums from each equipment to see if they match if it's not equipment problems,then something happen in the process .Do them over ,many times i have been told i was wrong and when i checked i was right and then i proved it. It maybe there is no solution between them this is a give and take. Check everything before you start to adjust anything, You maybe already correct. And do not mix apples and oranges, and make clear when you say you are using this type and the Grid were calculated from them, what kind of Grids.the word grid is used many ways in surveying some prefer to layout buildings by Grid lines plus staking the corners, You can have a defined projection Grid that has it's on Grid Azimuth North that is only good in that Grid, make plain what you are doing,then the solution will be more at hand