Hi guys
I've been asked to get involved in a construction project in my area, its a 7 storey concrete building about 250metres x 70metres.
The original topographical survey was carried out 7 years ago. A year ago the contractor came in and has now built the basement and ground floor.
They want me to provide them with as-built surveys of each floor and in addition to this some setting out services for walls and facades for each floor.
What makes me uncomfortable is the survey control. The contractor has put up targets on the neighbouring buildings and wants me to use them for my as-built survey and setting out.
What I'd like to do and would like to have done is traversed and checked the primary survey control for any errors and then shot in the targets.
Personally, I'm not a great fan of targets, but when I do use them I shoot them in from old control I quality check the control first and always shoot face 1 and 2 and ideally from more than one primary control station.
From what I understand the contractor set over one station, backsighted and shot his targets in. He could have backsighted and set over a hanging leg that didn't have errors adjusted out.
The spread of the targets is just on one side of the site and they're about 130 metres away from the centre of the site.
What would you do?
I'm confident that I can carry out a survey with great precision but how accurate to the original co-ordinates will be impossible to quantify. Setting out with any accuracy to the original co-ordinates is also impossible to quantify too.
Best regards, Andrew
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I would let the contractor dictate project deliverables, not the method in which you achieve them.?ÿ They are free to make suggestions but they are looking to hire a surveyor for a reason.
If you aren't comfortable, don't do it.?ÿ If you don't trust their control, but would do the project if you did a thorough re-measurement, then price it that way.
Liability chain for the lawsuits.
One more insured professional will mean potentially more money to settle with....
I've been asked to get involved in a construction project in my area, its a 7 storey concrete building about 250metres x 70metres.
What I'd like to do and would like to have done is traversed and checked the primary survey control for any errors and then shot in the targets.
What would you do?
I say you should only get involved on your own terms. If that means you need to run the control network again plus tie in and verify all their targets, then write that into the contract and charge appropriately. If they don't like it, they can take on all the liability and do it themselves.
Personally, I don't do any work at all on construction projects without control verification, even if we set it ourselves, because there's almost always a significant time gap between original control work and start of construction.
Definitely check into all control.?ÿ But unless it's a PL setback issue or datum concern, the building is now the monument and what should control for the rest of the project.?ÿ
?ÿShoot in all control, check the building and let the client know if there are any issues. And then decide if you can continue
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My first thought in reading this is to remember when that voice in your head says something is wrong, LISTEN TO THAT VOICE!
Some good advice has been given.?ÿ Don't get sucked in to being the nice guy to keep the contractor happy.?ÿ
Do it your way, after documenting it all in your contract with the appropriate fee, or walk.?ÿ You cannot lose money on a job you did not take, and for most of us, these are busy times; take the next one...
Ken
Thanks guys - great advice, will take it on board.
Seems like your first step would be contract to tie into control and as-built the foundation and first floor, and then see if it's worth continuing
I'd really like to check their control but they may not want to pay me to do it so....
If the contractor doesn't want me to check their control I can put a note on the drawings that the control use was the contractors, it has not been checked and my company bears no responsibility if it is incorrect.
I think you'd still be on the hook for some problems.?ÿ I'd incorporate the checking into my fee or do it on my own time prior, if I were you.?ÿ Disclaimers aren't a good way to begin a project like this.
Shouldn't take a lot of time to check into a couple points and benchmarks.?ÿ As said, you need to as-built the building to begin with, and then match everything to that.?ÿ (as long as the building conforms to setbacks and design elevation, etc.)
As said by others, if you're not 100% comfortable, before or after checking, walk away
First task for any construction job is to check through the control add extra or bring up any issues. I've never asked anyone if it's allowed.?ÿ
Do what you need to do to feel comfortable with your deliverable.?ÿ Saying control was supplied by others and not verified does not remove you of liability.
A huge question is why they are only bringing you in at this stage.?ÿ Who did the early work and why aren't they there now?
Good question - one I asked them. The setting out work so far has been done by the contractor. They need a 3rd party to verify the dimensions of the building and its structural elements and that they are in the correct place.
NEVER use someone else's control for control. Run your own control and show his control on all submittals. Make sure you have some secret off-site control the client does not know about. Could be a fun and profitable project.?ÿ
I disagree.?ÿ I'll use anyone's control, as long as I check into enough things that I'm satisfied it's good.?ÿ But after that, hasn't it become my control anyway??ÿ Doesn't really matter who set the points to begin with, does it.
I'll disagree as well. For continuity's sake?ÿ I'd prefer to use to supplied coordinates. But I could do so only after I had performed my own measurements and satisfied myself that those coordinates were as correct as anything I could produce. There is no point in introducing ambiguity at the 0.001' level (or probably even 0.01' level)?ÿ just to assert that I'm a better measurer than the last guy.?ÿ
In practice that commonly means that I would end up using many of the old coordinates while adjusting a few to my own numbers.?ÿ
I do agree about keeping some control in your back pocket.?ÿ ?ÿ ?ÿ
A bit too late, if you ask me.?ÿ They needed the 3rd party to tell them where to build and then find out if that is what they really did.?ÿ They obviously want you to prove to them that they don't need your services in the first place.?ÿ If you tell the truth and show they did not build per the plans, then you are the bad guy.
Do they want you to provide an asbuilt referenced to a specific coordinate system? It sounded like they wanted you to asbuilt the existing structure and verify dimensions before laying out the rest of the building. I would personally verify their control before using it. But if work has already taken place and that is the control they have used to do it, I would not just discard their control. That being said the controlling factor now is the building. I would be curious to hear how this turns out for you.