California Surveyors Forums

I'm doing a partial retracement of a survey conducted in 1971. This is in a heavily forested, steep area. I'm wondering what survey methods would have been most likely used at that time and what the expected accuracy might have been. I know that EDMs were not very portable at this time. I found two iron pipes at two corners of a 1/4 1/4 section to measure two feet longer than record using a total station with standard traverse methods. The record of survey that shows these was a survey of an area that stretched across an area of 2 sections and showed monuments having been set/found at all the 1/16 corners. Thanks.

The HP 3500 came out in 1971. For all intents and purposes it was the first EDM available for general use. Very few firms had one until 1972. The EDMs available in 1970 were VERY impracticle to use in a "forest traverse" environment. With that said, I presume a steel chain was used. A GOOD crew would achieve 1:5,000 to 1:10,000 running through the woods.

I would not expect two feet in a 1/4 1/4.

Hope this helps.

Thanks for the info. I would probably expect those accuracies also. I'm getting less that 1/1000 for this. However, I'm tempted to hold these, because the methods of section breakdown on paper are correct and I think it's silly in this very rural area of large acre parcels (40 ac.) to show a pipe off a couple of feet. There are no fences or other signs of possession. I think an ROS may be in order, though.

Check your messsages.

Yes, chain and transit. 1:5k would be in the range.

Richard,

This was not a dependent resurvey done by the BLM. It was a private survey done for some type of developer/investment firm.

Steep, forested area? I think that does not sound too bad actually. I generally will not get into a linear type of "precision math" and go with terrain/line of sight issues.

Even with an EDM I have seen surprisingly bad (per se) loop misclosures on my own work and I am pretty anal about things. Give yourself a short BS a few times and no way of cross checking, and it gets interesting.

I ran most of the traverse down a winding dirt logging road for about 1200 feet+/-. There were one or two shorter backsites (with distance ratios of 1.5:1). Only two courses were off the road down a steep hill to tie in one of these pipes. I'm thinking my measurements were pretty decent. I turned full sets for the whole traverse and I just checked my gun against an NGS baseline. I'm going to have to decide whether an ROS needs to be filed on this or not.

I am sure your methods and instrument are a lot better, and I suspect your errors are not material. I was taking your original post to mean you were not sure to accept the two pipes as being from the 1971 survey. It is hard to make a "proper" comment on this without seeing the record of course.

I can agree with others that it would seem quite reasonable to expect 1:5000 or better, but by experience in retracing such surveys, I know that 2' in a quarter mile is not terribly out of the ordinary, and therefore should be considered in many mountainous areas as falling within the expected error for a survey of that time period. I'm in agreement with Bryan on this.

Remember that the BLM had a minimum standard of 1:905, which they often exceeded, and which is not very far off from what you are finding in this 1/4 mile.

The instrumentation most likely utilized were a transit or theodolite and steel tape. Angles may have been repeated or they may have been turned only once (poor practice, but it happened). Distances were either measured by breaking chain often, or by slope chaining.

If break chaining, each horizontal measurement is a new opportunity to introduce errors of not holding the plumb string right at the pin (centering), holding the tape out of level as the distance is measured, and misreading the tape. if slope chaining, there would be fewer opportunities to introduce centering error, but you can add a higher likelihood of improper chain tension, misreading the vertical angle, the potential effect of uncompensated collimation error affecting the vertical angle reading, and bad math in performing the slope to horizontal distance reductions. With either method, there is also the potential of improper temperature correction.


More importantly, remember that as a retracing surveyor, it is your job to determine where the lines and points of the original survey were actually located, not where they should have been. If the monuments you found appear to be in the same locations that they were originally placed in, that survey was the first to establish those points on the ground, and it appears that they utilized appropriate methodology in determining the section breakdown (as opposed to whether they made high or poor quality measurements), then you have no authority or basis by which to reject the monuments.

I think that in most instances, under the circumstances you describe, you would be hard pressed to justify rejecting the monuments for disagreeing with the distance between them by 2'.

btaylor wrote:I am sure your methods and instrument are a lot better, and I suspect your errors are not material. I was taking your original post to mean you were not sure to accept the two pipes as being from the 1971 survey. It is hard to make a "proper" comment on this without seeing the record of course.

I viewed the question the same way. Even though I do not see the amount of difference between record and measured to be cause for alarm or to approach an amount constituting gross error or a reason to reject one or both monuments, I would consider the difference significant enough to show on a RS. it may depend upon what the foreseeable use of the land is, but when in doubt, file the RS.

If the pipes were relied on, I would definitely not reject them. If they are just "out there" and people never fenced to them, or even knew they existed, I would consider "rejecting" them, but every case is different.

I also simply like to "respect my elders" (I was born in 1971) and try to preserve the integrity of the hard work by holding to/refurbishing old monuments, and show record/measured differences. I can see if it affects things like a minimum area for development or something you can start coming up with reasons to "reject."

Never a black and white answer. I am always finding reasons to disagree with myself on my own older surveys, much less anyone else.

look at the big picture, how does it affect the ownership and the adjoiners? is all of the affected ownership private or public? in my world 2' over 1320' is not bad. Does it appear proper metheods where used? I had thought the BLM standard prior to 1972 was 1:300, which is well within the realm. Based on the date, terrian etc, 2' sounds good.

Thanks for all your input. From my research, the 1971 survey was the first survey of the sectional breakdowns. The methodology that was used is correct. I can't find any reason to reject them, except that the measurements are not the best accuracy I've ever seen. But from what others have said here, the accuracy is probably within reason. There are no fences or anything close to this pipe. It's way out in the woods. It looks like no one has located it since it was set in 1971.

I tried to attach the record of survey, but I'm not having any luck here.

MikeTurnrose wrote:I can't find any reason to reject them, except that the measurements are not the best accuracy I've ever seen. But from what others have said here, the accuracy is probably within reason.

Be careful using variance between your measurements and record dimensions as a reason to reject monuments even when you consider the variance to not be within reason.

The BLM Manual refers to "gross error" without really defining what that means. The courts will reject a monument if it appears to no longer be in its original position, if it clearly does not reflect the intent of the parties to the original transaction as demonstrated by their clear acts of ownership contrary to the monument location, or where the actual location of the monument produces an "absurd" result in the configuration of the parcel.

Many surveyors would consider most any deviation greater than "reasonably expected error" to constitute an absurd result. That's a very different standard from what the courts view as absurd, and so it is an irrelevant and incorrect standard to apply.

Two cases which come to mind are one of a riverfront parcel back East where a call to a particular monument resulted in an unusable parcel, or one which did not accommodate the home that went with it.

In the other, the subject property was a rancho (somewhere near Santa Cruz, IIRC) where an erroneous call was inserted, caused a very large misclosure, caused all subsequent calls to not fit the ground, and made a difference of several hundred acres in the resulting area described. Although the misclosure was a consideration, I believe it was the fact that the monuments, including a mountain ridge, could not be reached by the dimensions of the subsequent courses unless the "absurd" course was eliminated. It's not normally the magnitude of error in a particular dimension, but the effect of that error on the general configuration of the overall parcel and/or the effect on other called monuments that the court will consider.

There are no clear cut rules as to when a measurement error is one which should simply be reported but accepted vs. when it is considered absurd and must be rejected. The specifics of each survey other than relative error along a course must be considered in making the decision.

I would expect triangulation to be one of the primary methods in the days just before proliferation of EDM's. A couple of feet is very reasonable for triangulations.

It sounds like you are on the right track by looking at an acceptable procedure and methods of the day.