Another ROS/Corner Record dilemma

[MikeTurnrose]

I just finished a boundary survey of a 5 acre parcel in a heavily wooded steep area of the Santa Cruz Mountains. I found several monuments that are shown on recorded survey maps. The measurements I made are quite a bit different from what the prior surveys show, so I'm trying to decide whether an RS is required or not. All the lines I surveyed are shown on recorded maps, so that would eliminate one of the conditions for an RS. On one side of the parcel I measured between two pipes to be 803.88 feet. Two record maps show the dimension to be 806.55. One of the maps was done in 1975. The other was 1981. I feel good about my measurements. I did not close out the traverse, but did turn full sets to all my control points. I've done enough closed traverses with this gun (even in rugged terrain) where I think my measurements are accurate. One small source of possible error in my work would be using swing ties to tie in the pipes (couldn't see due to a tree being on line), but I don't think that would account for much discrepancy. On the other side of the property, I measured between two pipes and found the distance to be 825.67 v. 825.07 record map (no discrepancy here in my opinion) The two northern corners (which were way down a steep hill) measure 292.02 v. 289.34 (map) v. 290.87 (deed). I found another pipe along the west line that I'm not sure of the origin. It measures 195.01 v. 199.33 (record map). This pipe was not tagged and was in the middle of the road. This pipe may be the one that pushes the RS requirement, but I wanted to get others opinions. I'm not looking for criticism of my survey methods here. I'm just trying to make an informed decision on this. Thanks.

[Ric7308]

File an RS

[MikeTurnrose]

I was leaning that way, but it's not an easy phone call to the client asking them to shell out a $600 map checking fee. Map checking fees are another issue altogether. I have a clause in my contract that allows for the R/S trigger, but I had expected to obtain better measurement results in relation to the record, so this is unexpected.

[Jim Frame]

The public policy behind the ROS requirement is the maintenance of accurate public land net records. As standard of practice measurement capabilities improve over time, the concept of material discrepancy changes with them. Even in rough terrain, differences between measured and record distances on the order of a foot are hard to characterize as immaterial.

I agree with Ric.

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[pls5528]

The Santa Cruz Mountains has some very difficult terrain. Prior to wide use of electronic measuring devices, if not done propery, break chaining or slope chaining could be the cause of the dicrepancies. Proper care and procedure chaining in rough terrain (and in the flat land) was crucial to accurate measurements. In your case a Record of Survey is the proper thing to do.

[hellsangle]

Mike,

If I understand correctly, the point was behind a tree and you employed two swing ties. And assuming you tied the two points that had each had swing tie to the pipe . . . I also assume you did distance/distance calc? If so, there are two answers for a distance/distance calc. You might check to see if you have the correct one (which can be checked graphically in your software. Just in case . . . )?

Best,

Phil - Sonoma

[LS_8750]

Those hills are alive Mike. Blame it all on earthquakes. File the RoS, $460.

[E_Page]

The purpose of closing a traverse isn't just to have a closure resulting from any inaccuracies, or more accurately systematic errors in your instrumentation so that you can adjust it out to theoretically come closer to true positions.

One of the most important (the most important IMO) reason to close your traverse is for blunder detection. Even the most careful surveyors make mistakes from time to time. The surveyor who has never made a mistake has never measured anything. I was thinking the same thing that Phil mentioned. The point where you used 3 swing ties should alleviate the concern at that point, but the one with only 2 leaves more room for doubt. If you have any doubt at all, best go double check those or find some other demonstrable method of eliminating one of the 2 points a distance-distance intersection gives.


The RS filing requirement is not at all dependent upon whether or not you had prepared your client for the possibility or whther the client wants to pay the fees associated with preparing and filing the map. If you hit one or more of the triggers, you file the map. IMO, you have material discrepancies along at least 3 lines. If this is rough mountain property with little to no likelihood of high density development, the 0.60' in 825.7' is probably not material.

I see that 2.67' of discrepancy shows up on 2 lines. Are these discrepancies in similar directions? Are these relative to the same map? In each case, your distance is long. It may be a coincidence, or it may be indicative of errors in the previous surveyor's work which are not present in yours, but if one end of each of these lines was measured from on part of your control (same control point or same branch of your unclosed traverse), and the opposite ends of these lines were measured from another part of your control (point or branch of unclosed traverse), I'd have a serious question as to whether the discrepancy was a result of a mistake in the previous survey or a mistake in yours. If it were my survey and I had a pattern of discrepancies that I could not say with certainty (and demonstrate it with a closed traverse or other similarly certain checks) whether the error were mine or not, I'd be planning a return trip to close out the traverse, find a common point to tie visible from each branch of my open traverse, and/or double check measurements in the locations most likely to contain a blunder resulting in the discrepancies found.

Surveying in such terrain, material discrepancies are a high likelihood if not a certainty. A letter at the front end of the job accompanying the contract adequately explaining the possible or probable need to file an RS would have done one of 2 things. It would have prepared the client for the possibility of the cost of an RS, or it would have weeded out a cheapskate client that you are better off not working for.

"But times are tough and I need all the work I can get!"

If the client is so cheap that they will refuse to pay for the added cost of a RS, then you have 2 possible problems. One, you now have to weigh your ethics against your ability to pay the rent and buy groceries. Two, you are probably losing money or breaking even anyway. I'd rather sit at home and go broke slowly than work really hard to go broke faster.

[Dylan Kolstad]

I'll presume you know the quality of your survey work & measurements better than us.

If you feel based on the evidence in the field and your research that the survey monuments you found were not disturbed and serve as reasonable evidence of the "corner" locations despite the sloppy work, and if you were marking lines during this survey, you should do the RS to protect yourself and your client.

If you were hired to just find these monuments and feel you've completed the tasks under your agreement with the owners, educate them on the errors you're seeing and advise them that the pins are likely encroaching on the neighbors, and they're at risk of a dispute with neighbors in time if they fence or use every inch of the property. Recommend to them that they hire you to finish this boundary survey with a map and the reasons why same is a good idea. If they say no, well, maybe you'll be back later when said dispute arises, and your fees will suddenly be higher...

If you feel the monuments are not reliable for more reasons than just the poor measurements, to serve your client, you may need to do more field work and bugger the costs...

[Jim Frame]

If you were hired to just find these monuments and feel you've completed the tasks under your agreement with the owners, educate them on the errors you're seeing and advise them that the pins are likely encroaching on the neighbors

Advising your client that the monuments are not in the locations indicated by the deeds or maps constitutes disclosure of material discrepancy. As soon as you do that, you're on the hook for a ROS.

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[Woodcutter]

Evan is right on the money.

How do you know the error is per the original survey and not yours if you didn't close it out?

Blunders happen in many ways.

I once discovered a 1 meter error in a set of edm readings. 2 shots data collected both had the same reading.

Only way I knew it was because the traverse misclosed and I re-ran the traverse and found the discrepancy with the 2nd running. Neither we nor the instrument manufacturer could explain this exactly 1 meter error in edm reading.

With the same brand but different model of edm we also experienced 1000 meter edm "errors". The manufacture acknowledged that was a known but somewhat rare random occurance. I believe that the same electronic "malfunction" that caused the 1000 m error also caused the 1 m error.

The strange thing about both experiences of errors is that they were repeatable for the set up. i.e. we kept getting the error on multiple readings. We only got correct readings after breaking down the instrument and resetting it up. Very, very strange. Also very uncommon as we used the same instruments for thousands of shots and only experienced the couple of known instances.

Another time I watched a partner of mine set up a total station on a traverse point that had a relatively very short backsight. I noticed he didn't look through the optical plummet. As he was starting to turn his angles I walked over and took a look through the optical plummet and found he was 3 inches off of the occupied point. I calculated the potential error would have created over 5 minutes of bearing bust.

We would have caught it eventually as we close all traverses and even "stub shots" are shot using 2 separate backsights. I was fortunate in observing the blunder before it caused us to re-run a traverse.

Long story short. If you're misclosing against record, then you better check your work and never ever assume it is the other surveyor's work that is wrong if you haven't fully closed your traverse.

[dmi]

I must have slept through that lecture.

Rules of the Board for Professional Engineers and Land Surveyors
California Code of Regulations Title 16, Division 5 §§ 400-476

476. Code of Professional Conduct – Professional Land Surveying
(c) Representations:
(7) A licensee shall only express professional opinions that have a basis in fact or experience or accepted land surveying principles.

[7702]

Comments referring to the earlier work as being "sloppy" and "poor" because it doesn't agree within a couple feet of a stubbed out traverse performed 30 odd years later on steep, possibly unstable ground is a bit unfair to the original surveyors. They may have set those monuments with the utmost care. Monuments have a way of moving over the years, especially on steep, coastal property in California. And it's not all that uncommon for landowners to disturb them, either accidentally, or on purpose.

[LS_8750]

Well that's one of the beauties of having obsessive compulsive disorder.... Often having quadruple checked yourself on every control point five or six times, sometimes you can just say hey... My measurements are good! The previous guy was out... That's cool until you discover your best party chief is truly dislexic.... That's when a cut 0.96 becomes a fill 0.69.... Turns out he was OCD too, so he 92.5% of the time caught his own mistakes...

But again, when you have seen the damage caused to buildings within three miles of your job site caused by the Loma Prieta quake, you can rest yourself much easier when you find a bearing and distance call different from record by a couple, or a few feet. A found monument is just that. But then the next ridge over everything fits within a couple tenths. And then you inverse ridge to ridge and find a couple hundredths. Welcome to the Santa Cruz Mountains Mike.

Good luck with your error theory analysis in a country littered with ancient landslides and so seismically jumpy that the USGS records about 50 earthquakes a day ranging from 2.5-3.5 on the Richter scale within 25 miles of your job site.

I bet your ties are fine. I also bet I would find you out by at least 0.4 feet within a year assuming no substantial quakes happened in the area....

Cheers,
Clark

[Sean Ryan]

Mike, I didn't read anywhere where you set any points. Kind of a game changer if you hadn't.
Personally, I don't think I'd have the emotional strength to call someone 'off' and yet had not closed my own survey. Bite the bullet, close-out. Take the weight off your shoulders and keep the ghosts out of the closet, otherwise they'll just multiply.
Good luck.

[LS_8750]

I'm away from my desk Mike, but maybe google "Clark's Geology Map Santa Cruz" and "USGS earthquakes daily California". You will see what I'm talking about..

[RAM]

back to the orginal question, I have found that if I ask myself if I should file a map, the right answer is always FILE the MAP. If it is gray, FILE THE MAP., Better safe than sorry.

[land butcher]

Recently had a EDM shoot a bad distance to a distinctive topo point, off about 20ft. Don't know why, caught it reviewing the plot. Went back out and repeated the shot from same setup and got a correct result.
They do have their quirks. Nothing is perfect and we cover our butts with redundancy.

[Jim Frame]

They do have their quirks.

My Leica 1100 recently switched -- without my knowledge or consent -- to reflectorless and took 5 consecutive shots to the same spot on a wall. Unfortunately, they were supposed to be face-of-curb shots. I didn't notice until I was back at the office. :(

Okay, Mr. Robot, you've got my attention now. Happy?

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[MikeTurnrose]

I went out there yesterday and closed out the traverse. I closed less than .02'. I suppose that 1/68000 is good enough. :) Never hurts to check.