Caltrans LS and LSIT video and workbook question explanation
It has always been something other than 40. As is usually the case the original measurement was not correct. Proportioning is a legal exercise of attempting to put the error where it is. Why would you take the error in measuring between the 1/4 and the W.C. and place it in an unrelated measurement? If the notes indicate the W.C. was set on line it marks the section line, but chances are, we will measure different bearings. We don’t have the authority to change the line and make it straight.
The idea of putting the error in the fractional part is meant for original surveys. The owners of the closing lots aren’t subject to lose property because of a shortage in another person’s line.
What approach would you take?
I get 0.01′ different than 3 in both northing and easting, but I doubt that is the problem. The explanation that the W.C. is not necessarily on line, can’t be right, because question B which requires an assumption that the W.C. is on line.
I look at the WC as being set online, then it’s important to figure out which line, since they already occupied the E1/4 and started to survey to the CC then I would put the WC on the line between the E1/4 and the CC. From there I did a calc to get a new easting and it comes out about 31.3, which I don’t see in the answers. At that point 4 makes the most since.
At the end of the day the way to have the WC on the line is to put the angle in the section at the E1/4, if you put the E1/4 on line between the SE corner and the WC then the angle in the section is at the WC. WC’s I will consider to be online, off line points are usually described as reference monuments.
Anyway that’s how I would do it.
If you determine that the proper proportionate method is to single proportion between the witness corner and the SE Cor. of Sec. 6 then the record dimension between the two is 41.09 ch. and the measured is 41.454 ch., which would place the E1/4 Cor. 1.10 ch from the WC.
Should be:
If you determine that the proper proportionate method is to single proportion between the witness corner and the SE Cor. of Sec. 6 then the record dimension between the two is 41.07 ch. and the measured is 41.454 ch., which would place the E1/4 Cor. 1.08 ch. from the WC.
Actually 6-27 (2009).
The Manual disagrees (see section 6-27) , “..thus, in single proportionate measurement, the record bearing and distance is modified, and the witness corner becomes an angle point of the line.”
It is also untenable from a landowners perspective to have an an unmarked angle point that requires a complicated (from their perspective) calculation to find. That is not how the system was designed.
Your method also does not appear to follow the footsteps. Most notes will show the the original surveyor measured, to the best of their ability, on a line of constant bearing from a monumented point to the W.C., or the other way around. They did not change bearing at a calculated position.
BLM/GLO surveys use the term W.C. for both online and offline points. An R.M. is like an artificial bearing tree (hopefully more precise), referencing a monumented point.
Posted by: aliquot
The explanation that the W.C. is not necessarily on line, can’t be right, because question B which requires an assumption that the W.C. is on line.
Good point about question B!
To clarify, given the way the problem is presented I think C (proportion between the W.C. and the southeast section corner) is the best answer but I think the explanation for why McCavitt selected D is the W.C. is not necessarily on line therefore insufficient information is presented to calculate the position of the corner.
The question as presented is ambiguous at best and is poorly conceived, in my opinion.
Although the W.C. is not necessarily on line the way the diagram is drafted strongly implies that it is on line.
Protracted,
What I was trying to illustrate in my opening post was the way I usually “solve” a problem with one answer being “None of the above.” That being what logic and method was used to arrive at each answer. Then it is easier to evaluate if the correct method was used. If not, it’s “None of the above.” The first answer is wrong because it uses the record distance (we can assume that the witness corner was set online because the record dimensions are 41.07 ch. to the WC and 33.60 ch. from the WC to CC).
The second answer is wrong because it accepts the WC as BEING the E1/4, which it is clearly not.
The third answer has a proportional distance from the SE Cor. to the WC and it is on the line between the SE Cor. and the WC. That matches the default method for single proportion described in Sec. 6-27 (2009). So, all you need to do is check if the distance is the correct proportion. My apology for misreading the record distance as 41.09 in my initial post and leaving the mess.
I usually try and eliminate as many answers as I can before crunching the numbers. This problem is a good one because it includes information like the closing corner not being on the township line as defined by found corners 1 and 4, that are inserted to see if the test taker will be distracted by information that has no bearing on the solution. I included Sec. 7-35 on single proportion of lost corners because it includes witness corners among the list of control corners used in single proportionate methods.
The last thing to mention is if it was an offline WC, you should treat it like an original accessory to the corner; i.e. record bearing and distance.
So that leaves me like Dave, confused with the stated answer of D.
Protracted,
What I was trying to illustrate in my opening post was the way I usually “solve” a problem with one answer being “None of the above.” That being what logic and method was used to arrive at each answer. Then it is easier to evaluate if the correct method was used. If not, it’s “None of the above.” The first answer is wrong because it uses the record distance (we can assume that the witness corner was set online because the record dimensions are 41.07 ch. to the WC and 33.60 ch. from the WC to CC).
The second answer is wrong because it accepts the WC as BEING the E1/4, which it is clearly not.
The third answer has a proportional distance from the SE Cor. to the WC and it is on the line between the SE Cor. and the WC. That matches the default method for single proportion described in Sec. 6-27 (2009). So, all you need to do is check if the distance is the correct proportion. My apology for misreading the record distance as 41.09 in my initial post and leaving the mess.
I usually try and eliminate as many answers as I can before crunching the numbers. This problem is a good one because it includes information like the closing corner not being on the township line as defined by found corners 1 and 4, that are inserted to see if the test taker will be distracted by information that has no bearing on the solution. I included Sec. 7-35 on single proportion of lost corners because it includes witness corners among the list of control corners used in single proportionate methods.
The last thing to mention is if it was an offline WC, you should treat it like an original accessory to the corner; i.e. record bearing and distance.
So that leaves me like Dave, confused with the stated answer of D.
Right, this raises the important point that the approach to taking tests is different than working on real world problems. Real world problems have additional possibilities to gather more evidence or to know more information, perhaps after following this GLO surveyor through multiple townships, you know their particular bearing tree measuring method (side-center, face, etc) or other quirks and can accordingly follow in the footsteps. On tests, we work with what we are provided and there are test taking strategies that have nothing to do with the content at all.
I look at the WC as being set online, then it’s important to figure out which line, since they already occupied the E1/4 and started to survey to the CC then I would put the WC on the line between the E1/4 and the CC. From there I did a calc to get a new easting and it comes out about 31.3, which I don’t see in the answers. At that point 4 makes the most since.
At the end of the day the way to have the WC on the line is to put the angle in the section at the E1/4, if you put the E1/4 on line between the SE corner and the WC then the angle in the section is at the WC. WC’s I will consider to be online, off line points are usually described as reference monuments.
Anyway that’s how I would do it.
Thanks for the explanation. This is an approach which potentially fits the test constraints that the WC is on line as per question B and also the E1/4 is not determined by single proportion between the WC and the SE section corner. Again, perhaps highlighting the difference between contrived test questions and solving real world problems. Answer 3, single proportioning between the WC and the SE section corner, still sounds pretty good to me.
There are the paragraphs before, definitely open to interpretation.
“A witness corner is not the corner point but a witness to the true point for the corner. The corner point being witnessed is recovered when the witness corner is recovered.
Ordinarily a witness corner established in the prior sur-
vey and not placed on a line of the survey will fix the true point for the corner at record bearing and distance,
as does a bearing tree or bearing object.Where the witness corner was placed on a line of the survey, if no complications arise, the witness corner will be used as control in determining the true point for
the corner. If the factual statements in the field notes are clear as to interpretation, it is then merely a ques-
tion of record bearing and distance from the witness
corner to the true point for the corner.This presumes the section lines surveyed and marked in the field by
the United States surveyors are in fact record bearings and distances between recovered corners. However,
this is not usually the case. Therefore, in order to locate the true point for the corner, it will be necessary to
adopt bearings and distances as ascertained from the corresponding section line.”IMHO, 6-27 is very poorly worded and should be clarified.
A major difference is that the test is timed. Since you have limited time and a set number of answers to choose from, it is beneficial to employ short cuts. In the real world there is no right answer at the end of the test. In a real situation, I would have the original notes, which would have stated why the corner wasn’t monumented.
I have never had to set or calculate the position of a rectangular PLSS corner based on a witness corner I found and doubt that I ever will. My only “experience” is answering test questions. Module 4 of the CFedS training covers this topic and when I took the quiz in 2011 this question was the only one I missed. The question was to calculate the position of the 1/4 Cor. between Secs. 8 & 9 on the sample plat in the sleeve of the 1973 Manual. That’s when I found out that on-line and off-line witness corners are handled differently in the rectangular PLSS (I do believe I got the question correct on the CFedS exam). It had four sets of coordinates to choose from.
I mistakenly applied my experience with witness corners in mineral surveys and calculated the position like MightMoe did above. Other than, “that’s the way the Manual states to do it” I’ve never heard a good reason for why the BLM treats an off-line witness corner like a corner accessory, but uses proportionate methods for on-line witness corners. The corner is not lost as Aliquot points out above, so why if the witness corner is online does the proper method require a distant PLSS corner to arrive at the correct solution. Accessories are normally held over distant corners because the corner position based on the accessory tie(s) is more likely to set the corner at its original position.
I’m not implying that there is no good reason for doing it the way Sec. 6-27 describes; perhaps it is perceived as an appropriate variant of indexing.
I’ve never happened to see an offline W.C., but I’ve often seen these:
Some nearby townships have dozen’s of them.
It sounds good to me also, aliquot makes a very good point using 6-27, I need to actually check and see how I did my last W.C. for a 1/4. It’s been a while.
aliquot makes a good point about not wanting an angle point at a non monumented corner.
I agree that having the angle point be at the found witness corner is a good idea for the rectangular PLSS. For my work with mineral surveys the line is always extended through the witness corner; i.e. from the monumented corner through the witness corner to wherever the terminus of the line is. That can be the record distance, a proportionate distance based on the ratio of the record distance to the measured distance between the two corners or a not to exceed. The mining laws limit the length and width of lode mining claims to no more than 1500 ft. by 600 ft.
Here is an example of three witness corners (circles) on the endlines.
And this 3D drape shows the reason the WCs were set where they are.
A question on this problem came up several years ago, either on this site or the old POB site. The whole Problem A-4 1988 LS is poorly written with a lot of pertinent data left out in order to properly answer quite a few of the requested portions of the test. The “corn-nuts” for the S.C. Sections 31 & 32 (Point 1) are bogus compared with what is shown to the West. Therefore positioning anything in the South Line of Section 31 can??t be done. Since this problem was dated 1988, the 1973 Manual is/was the latest Manual in existence at that time. What Manual did exist at the time the survey was supposedly executed? Which also might have some bearing on deriving an answer for Part I.
Question G, No. 3, appears to have an error in how it was written. Says East and West Lines 20 chs. I think they meant to say North and South Lines 20 chs, if you look at the two distances for the North and South Lines of Lot 7.
Question I should have given the record call pertaining to how the W.C. was established when it was set. Makes a difference in placing the ?¬ corner to do the proportion. The only answer that calc??s is No. 3 and the W.C. would become an angle point.
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