I am working on a small ADA infill ramp and curb project. There are two about 700' street sections and a handful of isolated intersections with new ramps and crosswalks. Since i didn't set the control i started by occupying known control points from the cad file. There is a ton of different control points in the cad file because the area has been surveyed a lot over the years and the surveyor that did the topo set new project control as well as tied existing monuments and control points throughout the project as they went.?ÿ
I started on the North end of the project occupying and backsighting the official project control points. I found quickly that some of the points were off horizontally and vertically about .07' consistently. I had to do a guess and check method to find which were the actual "right ones" with checks against manhole rim elevations on the plans. Was wasting a lot of my time and cutting into my profit.?ÿ
Finally got ahold of the surveyor of record that set the control. They offered to paint the "good control points" for me and sent me a CSV of them. When i moved on to the first isolated intersection my setup over two of the points had an error of .07' vertical and .07' horizontal. Instead of wasting a bunch of time testing out setups on different points i just staked the ramp from the setup. My thought was at the end of the day i didn't get paid by the city to do the topography/control and i shouldn't be responsible for the crappy control. The points i staked for this ramp are correct relative to themselves and the point i used. Not like we are laying a sewer main at 0.2% here. I set a lot of control on my own and know i can expect them to be tight and this error isn't from my own equipment.
My question is if there was a bust somewhere and a ramp doesn't work do i really have any liability for it? I know it would be best to run levels through the whole thing, but that's not in my scope of work.?ÿ
I know it would be best to run levels through the whole thing, but that's not in my scope of work
FWIW.... The first two line items in every construction staking proposal I send out are:
- Project set-up and Review of Electronic Drawings
Project set-up and review of provided electronic drawings in preparation for stakeout services. Compute building grid lines from approved construction documents. Client should provide drawings at a minimum of two weeks prior to any stakeout order to allow for review and establishment of horizontal and vertical control as addressed under item #2. Also included in this line item is attendance at one (1) pre-construction meeting.
- Survey Control
Recover/verify/establish primary control network to perform stakeout. If control needs to be established, it will be tied into the same datum as the approved site plans. If no reliable control can be found, options for establishing new control will be discussed with the client and performed as an additional service on an hourly basis.
Once you decided to use what you knew to be bad control, you assumed the liability for that decision. You could have refused to continue staking until provided adequate control. Or you could do what you did and hope the error in the control is not large enough for it to cause a problem. But you can't say it is not my problem if you went ahead and used the control knowing it was bad.
the surveyor that did the topo set new project control as well as tied existing monuments and control points throughout the project as they went.
Getting handed a CAD file or a CSV with multiple control points that might or might not be viable anymore is amateur hour, at least for transportation and ADA design projects. There should be a stamped & signed control sheet in the construction plan set.
In any case, if we are provided control and none of it checks within tolerance, we're sending an RFI to the client along with an exhibit or narrative showing the busts that we are seeing, so they can go back to whoever ran the control and tell them to fulfill their end of the contract.
It's either that or they pay us to run in good control oriented to the project.
I don't care either way, but I am not taking on the liability unless we have written documentation that the client (a) knew about it and (b) expressly authorized us to continue work knowing that the control was bad.
It does happen occasionally, where they know that they can field-fit things within the amount of float that we are seeing in the control. But it is rare, and it must be documented.
I don't know what equipment you or the previous surveyor are using, but 0.07' horizontally is often an indication of the wrong prism constant between Leica Circle prisms and Leica 360° prisms from my experience. I can't speak for other brands/prisms.
Does the HC ramp tie back into existing sidewalks and pavement? How'd that match up? Setting your own control from crappy control still makes crappy control that "works" amongst itself. Find something that hits the existing conditions and go from there and not just zero deltas on your data collector.
Unfortunately, control issues seem to be a common occurrence when taking over a job from a previous surveyor(s). I probably run into at least once a year where either there is insufficient control or the control doesn’t check within itself. The cause of the latter could be anyones guess. ♂️ I just always assume there will be a lot of office work to sort it out and get things on track.
My question is if there was a bust somewhere and a ramp doesn't work do i really have any liability for it?
Yes. If you performed independent checks, found discrepancies, and proceeded to stake anyway... the contractor will 100% take you for a ride if there are busts (in this case probably slopes that are not ADA compliant) that your staking can be attributed to.
It does my heart good to learn that others are having trouble with supplied control. I sometimes think that I'm the only one. I've done lots of site development staking jobs, I can't remember a single one where suitable control was supplied- because it was a) sloppy, b) missing in whole or in part, or c) excluded altogether.
if there was a bust somewhere and a ramp doesn't work
Anytime, Anything, goes wrong, and someone suffers, they start looking for the easiest scape goat.
That's usually the closest surveyor...
My number one rule for using layout control that is provided to me by others is to check it before staking any point. I had a layout project one time where I required the client, a contractor, to provide me with control. He, in turn, had the town Engineer hand me a CD with the control and all of the design drawings in C3D format. The control worked almost perfectly within itself and matched design elevations of the CAD files.
After about a month of construction and almost 2,000 feet of curbing poured in front of the town Engineers construction inspector, a different inspector showed up on site and said something didn't look right and had a crew come out to check the elevations. Suddenly I get a call asking me where my elevations came from and I pointed out that she gave them to me on CD. She told me that my elevations were 0.35' too high and made the contractor rip out all of the curb he poured.
It turns out that another office of theirs lowered the control by 0.35' and I was provided with information that was not up to date. After all of the finger pointing and the law suite being filed, guess whose insurance company decided to settle, despite their hired experts agreeing with me?
The moral to this story, never trust information that is not your own, even if it works.
@chris-bouffard I just went to one same exact thing. Crews found control that we were given from a civil 3d file. Stamped plans and engineering being done. The control worked great well plenty good for our portion. I had the guys log a 4 hour static file plus check with vrs on 3 points all other verification was base rover . VRS and opus both checked hz vt within the uncertainty. We checked there stated position hz and vt horizontal it was within what error we saw relative so no biggy. Vertical was out .8’ so red flag went up had guys stroll down the road to a ngs bm less than a mile hit it. I made notes briefed the boss and gave him all the reports etc. I said we are not concerned with vertical for what we were asked to do but someone should point this out so if something happens someone’s aware. I have no idea what became of it.
Doesn’t help that while your trying to get the control or project figured out the contractor is pressuring you to get some layout on the ground or they’re threatening to charge you for their guys standing around waiting. Seems everyone waits until the day of needing stakes in the ground to call anymore. You ask the client how soon they need the layout done and usually they say they want to start digging tomorrow or even that afternoon.
This is why I can not understand contractor's eagerness to get into the layout game. Not that I mind it.
I'm not responsible for their poor planning. My proposals state that I need at least 2 day's prior notice on a staking request. I also state that I need time prior to construction activity to verify control. A lot of the time I do the verification along with setting up erosion control and construction fences.
My proposals state that I need at least 2 day's prior notice on a staking request.
Same with ours. In my experience the problems crop up when we jump on staking immediately at the beginning of the project, and start getting out there in the morning after being called the previous afternoon. The super/contractor gets used to this immediate service and begins expecting it for everything.
When our schedule inevitably clashes with theirs down the road, they feel blindsided at first, and then get very annoyed when we point out the language in our contract.
Not that I care too much how they feel as long as we are fulfilling our contract, but it can and does impact the relationship. The good supers understand this sort of thing. But I've only worked with a few really good ones.
@rover83 I wish i had 2 days advanced notice. I have several jobs where my crew is on site from the boss guidances and they call and say we need this or that staked. So i am scrambling to even find a job number much less set of plans and cad dwg. Many times i get that around 10 ish am. Crews on site by 8. So its find control ck and get it staked. Not a fun experience at all. The ones where existing ties like building or curb and gutter i can get done quicker because we have to match existing anyway. But a new site and someone else’s control and all those are the ones that make me pull my hair out.
That's a lot to unpack..
The short answer is, yes. Unless your contract is bulletproof you may end up on the hook.
There are several scope items and assumptions that go into every construction job we take. You can roll several into the statement, "You will pay me a premium rate to solve problems beyond my control, and more if you caused the problem". Never undertake a staking job without that, unless you are T&M at a heavily loaded rate.
When you have a design choice to make, DON'T. If you happen to be the design Engineer go ahead. As the Surveyor you need to lead the Engineer to a good answer, but never make the call. Even if it's a simple statement from them to 'match existing' get them to say it (preferably in an email).
There are crews hired by organizations to check ADA compliance. I won't debate the value of this, but I will say they can be brutal. Ped ramps are a less likely target than parking lots, but 0.07 vertical can mean remove and replace in either case.