So, are there any builders here who want to shed light on how you make the foundation level for such a large building, and what are the tolerances usually?
Others have suggested laser levels, and certainly that was used when we built our home. However GPS is likely used too. Close to 10 years ago my friend (a mining engineer) worked at an open pit mine. One of his jobs was to 'program' the bulldozers with their instructions each day. Basically the GPS unit was telling the operator where to go, and how much material to add or take away from that area. The tolerances were measured, iirc, to about an inch.
With that much activity on the site, I would suspect GPS to get the ground level because it doesn't need line-of-sight. A laser level would have blank spots wherever anything blocked it. However, I would guess laser would be used to set the foundation forms where it's critical to get to fractions of inch accuracy.
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the following steel work gives a second chance at truly leveling/plumbing (or make it possible to work in tighter tolerances).. the concrete though, i'd imagine they're still trying to get everything within an inch or less.. (and tighter in certain areas)
When we had our home built, I was astonished when the contractor made us decide on the flooring options while he was building the forms for the foundation walls. He was going to pour the foundation to within 1/8 of an inch. And whether we choose the engineered or natural wood floor made that much difference.
Since this is Job's dream, I wouldn't be at all surprised if 1/8 inch is the minimal tolerance they want. I have no idea how close to perfectly level you can get on building that size.
As an amature historian, I look at this construction and ponder who will build upon this site in thirty years when Apple, Inc has been purchased/merged into some other corporate multi-national. The only constant is change.
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December 2016 sounds about right. Keep in mind, the building itself will go up quicker than expected. It's mostly a steel structure, concrete subflooring and windows. Lots and lots of windows. Can't wait to visit it someday.
If Steve Jobs was still around, and with all due respect to his memory, they'd still be building in 30 years. You know he would be touring the site weekly - with a ruler. And changing his mind about the finishings. Being that passionate about something has it benefits and drawbacks, eh?
I'm going to bet they miss the Dec 2016 date though. The building may go up fast, but it's the interior that is going to bog them down. Just the wiring, plumbing, and especially networking is going to be a massive job. And Apple will want to incorporate some new technology that wasn't yet in use when the building was designed, and that will take time to incorporate into the plans.
... imho of course....