So I'm reading specs for a staking proposal and they look pretty decent. The monument preservation language is better than I've ever seen. Then I get to the staking requirements.
"Slope Stakes will be hub with tack and lathe. Horizontal and vertical tolerance is plus minus 0. 01'."
Oh well, baby steps...
thebionicman, post: 452410, member: 8136 wrote: So I'm reading specs for a staking proposal and they look pretty decent. The monument preservation language is better than I've ever seen. Then I get to the staking requirements.
"Slope Stakes will be hub with tack and lathe. Horizontal and vertical tolerance is plus minus 0. 01'."
Oh well, baby steps...
Those will be expensive slope stakes.;)
Just curious, is this a small site where slope stakes can be used to set a building or some structure?
I don't know if it should be addressed in specs sometimes, but there are at least a couple types of precision. global precision, and local (relative) precision. The relative precision between two adjacent hubs might be within 0.01', but they might be farther off from the project bench mark, and farther off yet from the nearest NGS NAVD'88 published bench mark. When a spec just kind of writes a precision of +/-0.01', you are being set up for failure if someone wants to argue that your elevations are off 0.03' from the project benchmark, (or worse, from the nearest NGS mark.)
You can certainly write the cuts and fills to the 0.01' on your lath cut sheet, and I suspect that is what they are looking for.
Tom Adams, post: 452417, member: 7285 wrote: I don't know if it should be addressed in specs sometimes, but there are at least a couple types of precision. global precision, and local (relative) precision. The relative precision between two adjacent hubs might be within 0.01', but they might be farther off from the project bench mark, and farther off yet from the nearest NGS NAVD'88 published bench mark. When a spec just kind of writes a precision of +/-0.01', you are being set up for failure if someone wants to argue that your elevations are off 0.03' from the project benchmark, (or worse, from the nearest NGS mark.)
You can certainly write the cuts and fills to the 0.01' on your lath cut sheet, and I suspect that is what they are looking for.
Setting a hub and tack within 0.01' h and v (relative) is arguably possible, but doing so for dirt is insanity. The concrete stake specs are 0.03' horizontal...
there's a local (very large) dirt company here that has an S.O.P. that goes a little something like this: about the time you've done the title and design work and are happy that everything fits, checks, clears, works, and is approved by the various entities who insist on weighing in on your work, you get a phone call. usually from the site super. "r********r says your control is bad."
it's clockwork. and i can't count how many times i've gone out and re-run levels and traverse through control and checked flat or within .01ish.
i suspect it's just their way to preemptively deflect any liability for their potential f-ups down the line. "hey- we said the control was bad from the beginning."
if there was a way to stipulate as to this specific sub in initial proposals, i would do it every time. they're the only ones who ever do it. actually, they're not, but the very rare times others have, they've been correct...
flyin solo, post: 452432, member: 8089 wrote: you get a phone call. usually from the site super. "r********r says your control is bad."
I think I relayed this before
Ring Ring
LARGE construction company: Hey this is Bob the field engineer out here at high profile project, we just were checking you grid line control and a couple of points are out by 0.003'
Surveyor: click
LARGE construction company; Hey this is Bob again, I think were were cut off...
Surveyor: No we weren't, click.
FWIW a project manager from the same company once informed me that an email from him authorizing extra work wasn't sufficient back up to provide when I was submitting the invoice for the extra work back to him. I think I actually said "So you're telling me your word is no good?". And they were all up in arms when I asked to be removed from their bid list...to be fair they were also my landlord at the time, so it did get awkward in the elevator occasionally :confused:
Tom Adams, post: 452417, member: 7285 wrote: I don't know if it should be addressed in specs sometimes, but there are at least a couple types of precision. global precision, and local (relative) precision. The relative precision between two adjacent hubs might be within 0.01', but they might be farther off from the project bench mark, and farther off yet from the nearest NGS NAVD'88 published bench mark. When a spec just kind of writes a precision of +/-0.01', you are being set up for failure if someone wants to argue that your elevations are off 0.03' from the project benchmark, (or worse, from the nearest NGS mark.)
You can certainly write the cuts and fills to the 0.01' on your lath cut sheet, and I suspect that is what they are looking for.
I was staking for a boiler house in a paper mill many years ago and was asked by the Boiler Makers for a bench mark. We ad Dumpy levels and Philly rods so I set the benchmark (on an anchor bolt) and wrote the elevation on the column (i,e. 878.49). I was called about an hour later and told that they needed the elevation to the thousandth. No benchmark on the site was to the thousandth and we didn't have a precise tilting level so I just walked over and wrote an extra zero on the elevation. That boiler worked for nearly 40 years before they closed the paper mill so I guess the elevation was Okay.
Andy
thebionicman, post: 452429, member: 8136 wrote: Setting a hub and tack within 0.01' h and v (relative) is arguably possible, but doing so for dirt is insanity. The concrete stake specs are 0.03' horizontal...
I agree. And it's hard to discuss precision to a non-surveyor. These guys are also going to say, "Why can't you do it. That surveyor over there was able to meet those specs". And they are often seeing cuts written to the hundredth.
We use Leica sprinter digital levels that read to the thousandth. We record to the thousand in our level loops but as a general rule of thumb don't ever give elevations to any contractor to the thousandth. A hundredth for dirt is ridiculous and a waste of time but if they're paying...
Tom Adams, post: 452444, member: 7285 wrote: I agree. And it's hard to discuss precision to a non-surveyor. These guys are also going to say, "Why can't you do it. That surveyor over there was able to meet those specs". And they are often seeing cuts written to the hundredth.
When I get told that, I tell them that the other surveyor was lying to them.
Tommy Young, post: 452602, member: 703 wrote: When I get told that, I tell them that the other surveyor was lying to them.
You have a watch, right?. What time is it? No...to the second. No, that was the time 3 seconds ago - according to your watch. My watch says ____, which is different from yours by almost 10 seconds. Is mine wrong, or is yours? Neither, you say? Both? Now, meet me here next Tuesday at the same time. Not about the same time. To the second. What, you can't do it? Doesn't your watch have a seconds hand?
thebionicman, post: 452410, member: 8136 wrote: So I'm reading specs for a staking proposal and they look pretty decent. The monument preservation language is better than I've ever seen. Then I get to the staking requirements.
"Slope Stakes will be hub with tack and lathe. Horizontal and vertical tolerance is plus minus 0. 01'."
Oh well, baby steps...
Well, look at the bright side. If it was a metric job it would be a millimeter!
did someone misplace the decimal
I'm working on a project where the scope says something like '...to be surveyed with equipment capable of +/-0.03' horizontal precision and 0.06' vertical precision'. That seemed like a smart way to write it.