How much accuracy can you afford?

April 22, 2009
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Posted By Nate Dearyan on 4/21/2009 at 1:31 PM

This is a fundamental question.
How much accuracy is necessary.

Like staking a catchbasin. The Left/Right position relative to the road had better be right, but the STATION being off a foot or 2 (most of the time) does not matter. If the catch basin is on a long steep hill, then if the invert is 1 foot out, it won't hurt things. But if you are running in flat land, that foot could kill your profit.

It all comes down to KNOWING how much accuracy is NEEDED for the project. The higher accuracy, the more money.

Or surveying with RTK. If you are surveying a quarter section, then maybe 0.20' error on each corner, may be good enough. And the vertical being out by 100' does not matter. But if you are surveying 0.10 acre lots, in a flat area, maybe you'd better go with 0.03' error per mon max error, horizontal.

Maybe I balling centerline of river is good enough. But, sometimes, we can get away with a simple ESTIMATION of where C/L is. Other times, you had better MEASURE the banks, and/or the thalweg. (Thalweg is the thread, if the stream were nearly dry)

The key to profitability is KNOWING how much accuracy is needed.

Over-do it, and you have wasted time.
Under-do it, and you have liability.


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