After the surveyor has run a brief automatic plausibility check of the instrument on station, we store the data on a PC card and download them daily to our central database from the various instruments. This avoids not only the subjective errors from different observers, it also prevents transfer errors. With hundreds of points to check and document for subsidence every week, it’s important for us to be able to send out some of the younger and less experienced staff into the field and still have them come back with complete sets of accurate data.
The Leica digital levels are th only ones that make such efficient surveying possible, because its image-recognition software automatically records with extreme accuracy the invar staff’s scale position. That not only gives us an opportunity for employing young people on the site to do an interesting job and get practical on-the-job experience. It also saves us an average 50% of time on the survey itself, and that also means savings in wages and salaries." That comment was made by the chief surveyor on the world’s fastest construction site.
Professional surveying produces best results on Chek Lap Kok
If one counts not only the Airport Authority’s own seventy professional surveyors, survey technicians, photogrammetry and computing-survey staff, but also all those who work for the various construction consortia and the large number of subcontractors, one comes to the staggering total of two to three hundred surveyors on Chek Lap Kok who are sometimes on the job at the same time. The Airport Authority’s Ian Ayson and his survey team are not alone in relying on Leica surveying instruments. For most of the other professionals who work for the contractors, Leica equipment is also their standard of quality.
To date Ian Ayson has been very satisfied with the efforts of all concerned: "All our triangulation traverses close extremely well. In terms of accuracy, our margin of error is well below the specified standard. The height profiles that we survey at frequent and regular intervals closely match the computer forecasts of subsidence on the time scale. My experience of five years here on Chek Lap Kok tells me that it will stay that way in future."
When Hong Kong’s new airport reaches its full extent in the next decade, up to 87 million passengers will benefit from the precision work that Chek Lap Kok’s surveyors, engineers, and contractors are now in the process of doing. In surveying, too, the third millennium is approaching with giant steps.
