I have encountered engineers questioning survey accuracies in a recent project. We have been doing precise levelling, self-closed double run lines, each lines involve at least 2 benchmarks, consistent benchmarks and levelling routes for the monitoring points, INVAR staff, two-peg test before every field work with collimation error compensation applied (and check again to see if it works), only foresight and back-sight with no IS just for sure....The job's requirements are tight as the alarm will turn on if the settlement reached 3mm.
And then the engineers always question if the survey quality/accuracy is good enough as they see a couple of +/-0.5mm along the way. Apparently they don't know about random error theory and they think survey error is something wrong or mistakes committed by surveyors. I tried all I can to do the explanation, and I guess many of them fall into a fallacy: We don't know if the surveyor's right, but according to what we (engineers) know, this structure was built on foundation on a rock mountain so there is no reason for the movement, therefore it must be the error in surveying causing those strange readings.
Have you encountered these situations and how do u eventually work out a solution?
Chris
