California Surveyors Forums

Jim Frame wrote:I agree that to knowingly remove significant figures from a record measurement (e.g. showing a bearing originally reported as N 89°22'10" E as N 89°22' E) would be improper, and possibly even fraudulent. However, I don't see anything improper in adding insignificant digits to one..

In the sentences immediately following the one you quoted, I explained why it's improper.

Jim Frame wrote:When I show a record measurement, I do so only for purposes of comparison, not verification of that measurer's results. It's a pointer to the evidence I considered, and anyone who chooses not to accept my reported measurements would be remiss not to investigate the original source. Expressing the record measurement in the same manner as my own measurement makes the visual comparison easier..

When I'm using a record bearing in a description, if it's for comparison to a dimension based on my measurements or other more reliably precise data, I put that record measurement in parens and to the precision reported in the original record. Part of the comparison is the difference in precision. If I am using the imprecise record dimension for a course in my description (not as a comparison to the record), I don't want anyone to infer that I have made some measurements or other analysis that imparts a more precision to the dimension. By adding significant figures, since I am licensed as an expert, among other knowledge, as expert measurer and analyzer/quantifier of errors and uncertainties in measurements, that is exactly what I would be doing. It's exactly what you are doing whether you choose to see that or not.

Yes, another surveyor would be remiss to not compare my description to a referenced previous record on which the description or a portion of it is based, but I can't control the competency with which another surveyor practiuces. I can however, minimize the possibility of him malpracticing based upon use of a record I produce by properly reporting the data.

That brings up another question to this though, do you adequately reference records from which you pull record dimensions that you utilize in the descriptions you write? Not all surveyors do. In fact, I'm actually apalled at the lack of skill with which some surveyors write descriptions. It's often no better than an average title officer or paralegal could do. Missing calls to controlling monuments or bounds, missing calls to surveys the descriptions are intended to follow and by which future re-establishment of the boundary is intended to be controlled, lack of adequate redundant data, lack of the fact that the description reflects grid distances rather than ground (when it does), and when that might be indicated, a lack of an appropriate scale factor to convert reported grid distances to ground.

In grading the exam in years past, most failed the dramatically dumbed down from any real life descriptions they were expected to write. And many of those people are now licensed.

Uh oh, I'm ranting.... moving on...

Jim Frame wrote:In a related matter, when I report the direction of a 10-foot boundary course to the nearest second, I do so only as a matter of custom, not as an expression of accuracy. In no way do I imply that I determined the direction of that course to the nearest second. If some future surveyor takes that measurement and holds it to the exclusion of higher evidence (e.g. a fence line or porch corner), that's his negligence, not mine.

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With currently measured data, it is always viewed (or should be) in light of the capabilities for precision of the tools and techniques used, or likely used to produce the data, and the physical limitations to realistic actual precision. Same holds true for historic record data.

Conversely, on a 10' course, +/- 1' makes about 0.003' of positional error. The professional must also be able to discern when the reporting convention for a particular time period of a record exceeds the reasonable capabilities of the methods and equipment used to ascertain the data reported.

The reporting convention in any given era is generally commensurate with or slightly exceeds the measuring precision capabilities of the instrumentation and methods used at the time coupled with the reasonable certainties of the adjustment methods commonly in use at the time as applied to normal survey work.

When I started surveying, many surveyors, enough to call it standard practice, would never report a direction to a reading more precise than to the nearest 10". That was very common through the 1st half of the last century right up into the 60s, slowly giving way to reporting to the nearest 1" over the next 30 years. In the mid to late 1800s, it was common to report directions to the nearest 1/4 degree and distances to the nearest link. In the 1700s and very early 1800s, directions were commonly reported to the nearest degree and distances to the nearest 1/4 rod (about 4 ft). Going farther back in time, directions were called out as North by Northeast, Southwest, etc., generally indicating a precision of 22 1/2 or maybe 11 1/4 degrees, and distance units that might be to the nearest rod or even less precise.

Again, if you are writing a description utilizing record data that was originally written to the nearest degree and nearest vara (about 3'), but you convert it and report it to the second of arc and hundredth of a foot, you are setting up the circumstance in which some future surveyor or other person interpreting the description will take those levels of precision very literally as clearly expressing the intent and end up placing corners and lines many feet from where they were intended to be. Why would you want to contribute to that possibility (likelihood as I see it)?

Record data, used as the dimension in a description or reported for comparison purposes should always be reported to the precision of the original record or to the reporting convention of the era in which it was written, and should be stated in the units of the original data. Conversions from other units should be clearly indicated as mere conversions and should not imply a greater precision (i.e. 12 1/4 rods = approx 200', not 202.13').

How you report data has as much meaning as what the data is that you are reporting. You are presumed to have superior knowledge of the meaning of such data. Someone who recognizes that might presume that you are exercising that expertise in your practice, so it's better that you do.

I've been trying to recall an instance in which the precision of a record dimension has affected my decision regarding the location of a parcel line, but I'm coming up empty. When I've judged a record dimension to be the best evidence of location, it hasn't mattered whether the record was expressed to the nearest foot, tenth or hundredth, or degree, minute or second -- I held it because I found nothing to contradict it.

I do agree that a deviation from the customary expressed precision can be useful as a warning to others not to rely upon a reported dimension alone. For example, when I prepare annexation maps, I round directions to the nearest minute and distances to the nearest foot, qualifying the courses to the appropriate controlling documents. That makes it less likely that the description will find its way into the hands of a surveyor and lead him/her to hold the record dimensions as controlling. But that's the converse of the situation under discussion.

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I do as others said, I thought I was the only one.

If the record source says N 45°45' E then that is what I put on the map or repeat in the Description I am writing.

It is not something I am going to get extremely bent out of shape over, though. If someone else wants to write N 45°45'00" E then I frankly have bigger fish to fry.

I also do like Jim, which is to express my bearings to the nearest second although sometimes I don't if the distance is a very short tie, say a foot or so to another monument.

An aside: Sometimes on old Spink subdivision maps (1950s) it seems like they sometimes left the seconds off just as a convenience so they could cram one more bearing in there. Spink did all of the surveying in Spink subdivisions so they had the real data back at the office which isn't very helpful now.

In the old days Spink believed it was a waste of paper to use 2 sheets if you could get away with 1, and they churned out a whole bunch of curvy subdivision maps at 100-scale. That may be the origin of the Sac County convention of defining curves solely by radius and long chord.

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"Conversely, on a 10' course, +/- 1' makes about 0.003' of positional error. The professional must also be able to discern when the reporting convention for a particular time period of a record exceeds the reasonable capabilities of the methods and equipment used to ascertain the data reported."

Some years back a communications company wanted a 10ft baseline set during the topo of a proposed transmission tower. They wanted the bearing to
xx-xx-xx.xx. I turned down the work because I told them that kind of accuracy was not possible and they refused to reduce the requirement. No way was I going to sign a contract with requirements impossible to meet.


"I also do like Jim, which is to express my bearings to the nearest second although sometimes I don't if the distance is a very short tie, say a foot or so to another monument."

I think we are missing the point here. We are discussing a line we did not measure writing a record data description and being told to increase the significant figures of the data.
I have traversed record maps with short distances on them (less than a foot long), and regardless of the significant figures in the original bearing my map of the resurvey was to the nearest second. True, I can't measure that close but it has the same significant figures of the rest of the legs. I have produced new subdivision maps with short legs and the bearings are all to the nearest second.

The situation I was indicating is where I have found a monument for a corner and there is some other monument-looking object nearby.

I don't do subdivisions, only retracements.

For example, "Found 4"x4" concrete monument with CDF brass cap, up 1.5', a 3/4" rebar, no tag, up 0.5' bears N 12°12' E 5.19'"

If I measure the BTs with my Silva Ranger and rag tape then they get nearest degree, nearest tenth. "A yellow bearing tree tag on 48" redwood bears N 45° E 20.2'"