All,
I am in a sticky situation....Situation:
We were contracted to stake out piles for a building approx. 250x800. Developing a box with this phase of work was not possible due to grading etc. Overall I wasn't highly concerned as the pile were driven wood with a tolerance of basically 0.33'.
Now the situation becomes more interesting. We are requested in the field to stake out a box basically 100*x200 at the southern end of the building (the pad for the north end of the building was still be graded, etc at this time) by the in field site foreman. Coincidentally, I was on the phone with PM and he flipped out asking why were doing this? Who requested it? and he wasn't going to pay for it.
About 2 weeks later we are called to asbuilt the bolt patterns for the project. The layout crew (not us) had used the 100x200 box at the southern end of the building to push their bolt patterns north almost the entire length of the building. Of course this has lead to almost 90% of the bolt patterns being out as much as 0.21' at the north end of the building. What we determined is that the layout crew had been pretty good between bolt patern sets, but had an accumulating error across the building (I would expect this). The crew was using a theodolite and chain.
OF course now it is hitting the fan.
My questions for you all;
1-In 20 years of surveying I have never laid out a building from a small box. We have always created a larger box with at least four corners. My impression is that there would be no way to successfully stake out a building of this size without a proper box regardless of equipment? Am I off base here
2-If any of you have worked with Cooper, is their firms practice not to have a surveyor set out a minimum box? I just cannot believe that a big building contractor would not always stake out a box prior to concrete work. I may be wrong, but I would like your feedback.
1- not my expertise, accumulated error happens, but people deal with it, and have been for many centuries. skill is needed...
2- be careful discussing that here, this is public.
many thousands of projects are laid out by the work crews without any "surveyor" ever involved.
If you laid things out wrong, fess up, minimize and damages. maybe a simple redesign will be the best path.
If your work was used incorrectly, then review your notes, summarize, and document.
stuff happens
Theodolite and tape is actually a very good way - very possibly better that raying in by total station - to lay out 90 degree angles and points that are on a level surface less than a tape length apart. Not quite sure what you mean by "box", but projecting some layout points 4x obviously has it's consequences. As I read it you just have a building that is canted off 0.2' from it's theoretical position. Could be that is a problem that can be overcome without tearing up a lot of concrete?
Peter-Point taken...
Mark- Traditionally on big building we would create a four point box around the building (Quad angle, diagonals checked, etc) usually offset from the column/building lines a prescribed distance per the layout crew. From there the layout crew would set the other column lines for the building, turn their 90's, run their strings, tape off their distances, etc....Sometimes the also request that the interior column lines get staked, but that is rarer and rarer these days.
Plunging a 200 foot line ahead 600 feet falls within the procedures that are not correct but certainly not unheard of.
Sometimes you need to groove a little, the PM flipping out was story foreshadow my man, would have been a good time to pull the hubs and replace with spray paint.
I would not take company size as a for sure insurance against incompetent or irresponsible practices as a general rule.
A 4 point building box does not cut it for large buildings, you need two 4 point boxes, one box with the offsets to the sides and one box with the offsets to the ends. 4 string lines intersect and make the building box. A transit is definitely sufficient to set up on one offset, backsight it's mate and lay out anything on or near (with offsets) that particular building line.
However, I misread a building/crane run footer line drawing once, which had a building line, crane run line and footer center line, each 1'4" from the other. The survey crew checked the footer foundations before we set the footer column forms. They informed me I was 1'4" off, and I replied, yes, but 1'4" exactly. It was determined that the 8'x14' footers were large enough that we just had to drill and grout in some additional rebars.
On another job for a 100' long lathe foundation, we had a single foundation pour with 186 anchor bolts with 1/8" clearance in the bolt holes. The millwrights would then set the 100' long steel base plate. One bolt was off and had to be drilled and reset. A laborer had left the concrete vibrator on right next to that bolt while he waited for the next concrete load. A least I was happy with my original bolt pattern layout.
Paul in PA
While having perfectly good 100ft K&E inch tapes, we always converted inches into tenths and used a Lufkin highway chrome clad.
We found it necessary to measure the complete distance from beginning to end of any bolt layout before marking any locations because many changes were happening in the design office and the layout crews were not always given the latest plans.
Just because the engineers in design thought it up, the fab department would make changes because of available steel to piece the parts together. That meant measuring the steel in the yard to see if it matched the plans.
Then there was the day the white hat was holding the plans 180å¡ from actual alignment...........
nope, nope and nope, I don't miss construction at all..........
I would guess you were correct in that it's a bad practice to propagate the smaller discrepancies in measurement from the South end in some kind of OTJ training in error extrapolation. I'm guessing again that this was the contractors layout crew, applying a bad practice, and ultimately laying the responsibility at your feet without consulting you on their intention, beforehand. That sounds more like a culpability issue more than a simple best practices issue. And i'm not a lawyer or registered surveyor, but it seems to me if they proceeded with survey operations without consulting or informing you, they would have a difficult time assigning blame. But i'm just the field crew - caveat emptor
Ole cooper construction eh? We have them here but they go by Martinez Construction.
Haven't had too many problems with them.
If you are using TBC-HCE you can drag and drop your .spj file in and see exactly what your layout looked like compared to the plan. Go out and asbuilts their bolts and bring them in also. It will make a stunning visual for everyone concerned. Then you can ask coop , who you gonna believe, me or you lying eyes.
didn't read the op well. You staked a box or envelope. Somehow I had a picture of a layout crew building off your pile stakes.
R.J.- I am trying to be vague, so I know the post is hard to read. We never staked an envelope or box for the whole building. We just did a box based on a set of column lines at one end.
Paul-I prefer to doing things in the manner you describe, but as of late that isn't the case in what the contractors are requesting. To the defense of most of the building contractors I am working with at the moment though, they do have excellent layout crews.
Thanks everyone, your thoughts are highly appreciated.
That's a big building. I would do an 8 point box (double offsets at corners in both directions so intersecting offset lines gives you the corners). You are right in my opinion though. That box would be larger than the building, so if you had a couple hundredths error on the outside you should have less than that everywhere within the box.
Really I'd prefer to layout offsets from the column lines as well. Maybe even every other one or something. Then they can't screw it up. I'm spoiled though - I work for a construction contractor directly, so I usually over-layout everything. The result - owner has to pay my salary but doesn't have to deal with this kind of crap.....ever.....unless I screw up!
