Sir,i have some issues to ask about getting started for building layout such foundation and gridline offset,which method advisable and accurate to use in 300m x 108m building by coordinates method or angle/chaining method.thank you sir i realy need ur advise.thank u
This Content Originally Published by a land surveyor to Land Surveyors United Network
First what is a coordinate method and a angle/ chaining method. This is a very large building envelope.Coordinates can be used no matter how you laid the building out.Either radially or right angle.The challenge comes on how you will measure your distances.You say chain, are you talking of a steel tape.This was done at one time before EDM's or Total Station. But temperature correction played a big part in this method.Also how good one was at chaining, I would ask anyone on their skill at this.
Or you could use a invar nickel tape with about one-thirtieth correction of a ordinary steel tape. This is not a easy task on a building this large. Even today temperature will play in to how you do this, Angles and distance with a Total Station as Ted has also indicated . Heat waves play a part on how good your angles are. A umbrella over the gun midday helps. But turn your angles early before the heat waves start as already been said.
Daniel made some good points and A Murali babu did also. No matter how you do it Radially or Right angles,I would check my corners for 90 degrees and the diagonal distances. All instruments contain a small error so always on something like this double center the gun on your 90 degree angles and your equipment being correct, instrument and rods are most important. Builders work off of 90 degrees and diagonals.
Most do not understand coordinates, that is your job. So i am still lost at your question on coordinates because you can use coordinates no matter how you do it but a EDM is always better for you to measure with.
I have the same question as Billy. Any position, regardless of how it is established can be expressed in coordinates. It is said that GPS is the most precise method of measuring distance but there is a difference between distance measurement & positional tolerance. Do the plans & specifications specify a required minimum positional tolerance? The continuing education courses I have taken on construction surveying over the years all recommend setting lots of reference points & always check & recheck your work. Some checks offer a stronger solution than others but if you keep your instruments in good calibration, do good careful work & don't skimp on checks, you are not likely to have any problems. The biggest source of errors by far that I have witnessed in construction have been caused by errors in the plans or misinterpretation of the plans. Most surveyors can do better than a centimeter or two in 300 meters but spread out over a 300 meter distance, it is doubtful it will ever be noticed.
I am agree to you sir charlie,so i prefer to do building layout and stablished gridline by coordinates method.
Correct.. i agrre with Billy Brooks, and ill say it again EDM is the better to make a measurement this days..