Create Section Corner Position Using Only Accessories

Using the accessories is not a problem, that is what they are there for.?ÿ I would recommend using an instrument to tie them vs RTK given the short distances usually associated with accessories.?ÿ Distance is your fried with GNSS.

As for methodology, I would tie all of them and then start off looking at them together holistically.?ÿ If the notes give good bearings then you could throw them in along with distances.?ÿ If the best fit of all accessories fits record then you have it.?ÿ Only if I found one to be significantly off would I withhold it from the solution.

What John said. Of course this presumes youƒ??re happy with the pedigree of the position youƒ??re perpetuating. Be thankful you have 3. It wonƒ??t hurt to check a few adjacent lines for bearing and distance while youƒ??re at itƒ??. ?ÿAlso wouldnƒ??t hurt to establish substantial reference mons if the 3 accessories youƒ??re looking at arenƒ??t robust and have a significant expected longevity. Do you need to put something in the road over large pipe??ÿ

I agree, this sounds like a job for a total station. Measure all the distances and angles you can between the reference points.?ÿ Then either use least squares, or else plot a solution for the corner from each pair of ties and see how they agree.?ÿ If the triangle formed by the three solution points is small, use its center of gravity. If one point is far off the other two, then maybe disregard it.

Might double check to see if the ties were shot in horizontally or were they taped in at a slope distance to the former level at which they measured.?ÿ ?ÿ That should get you close enough to dig a small hole in the new asphalt to find the prior marker.?ÿ They probably simply paved right over it.?ÿ We have found tons of old corners by digging through the new asphalt.

BTW, that is a sure way to get the attention of the appropriate party.?ÿ You aren't doing anything wrong.?ÿ They did by obliterating a very important monument.?ÿ They have a responsibility to protect section corner monuments, etc.?ÿ Sometimes, they need to have that fact reinforced.?ÿ Repeatedly.?ÿ Especially when key personnel leave and someone new comes in.

Once, we dug through a four inch layer of fresh asphalt and then down about ten more inches to get to the existing monument.?ÿ A county employee witnessed our activities and told us it was placed two days earlier.?ÿ I then called his boss and chewed on his butt for awhile.?ÿ We haven't had a significant issue with obliterated corners in pavement in that county again.

I like everything cow said.?ÿ
N

@holy-cow people who slope chajn accessories need beaten. Severely. Repeatedly. Often...

Posted by: @thebionicman

Maybe not if they label the ties as slope, but still should be encouraged to do horizontal.

@thebionicman?ÿ

Just once.... unless it continues!

Posted by: @rankin_file

Also wouldnƒ??t hurt to establish substantial reference mons if the 3 accessories youƒ??re looking at arenƒ??t robust and have a significant expected longevity. Do you need to put something in the road over large pipe??ÿ

Robust in terms of stability? All 3 were set in concrete and are protected by a guard rail. I assume a nail and disc were set in the road because of the large pipe running underneath the road.

@field-dog?ÿ

Depends on the depth to the large pipe.?ÿ Cotton spindles, railroad spikes and 12-inch iron bars can be used in most cases.?ÿ Leave more references than normal because eventually (decades) that pipe will be replaced.

Slope ties are great.?ÿ Very quick determination of where the monument SHOULD be found.?ÿ There are no guarantees in life.

On a route survey I have two sets of ties.?ÿ One with slope ties and the other with different references using horizontal ties farther from the corner, thus more likely to still be found after construction.

@holy-cow accessories are part of the monument, ranked only below the undisturbed monument of record. The ties should be of a quality to place the monument with certainty if it is disturbed. Slope chaining doesn't cut it.

I hear two arguments on that.

Most common, the GLO didn't survey it thst well, why should I. Because once patented your crappy survey effectively transfers property from ine owner to another.

Next up is, I only need ties to find the monument. My answer to this: read a book. Learn the purpose of accessories or find a new line of work (preferably in a colonial state).

We will never get the public to respect the critical infrastructure of the PLSS unless we respect it ourselves..?ÿ

My .02, Tom

@thebionicman?ÿ

What is your typical source of solid, long-term, repeatable reference points??ÿ In rural areas it is difficult to find much of anything for which shots via GPS make any sense.?ÿ Driving bars for references introduces more problems than benefits.?ÿ Besides, a tape measure is more accurate than GPS.

@holy-cow I agree on rebar. We select or set different items depending on the circumstances. One of my favorites is a fence post that does not match the type or color of the existing fence. A T-post driven with the ribs reversed and at a different height stands out well. True reference monuments below the plow line with rare earth magnets work well too. There is nearly always something reasonable if you plan for it.?ÿ

@thebionicman?ÿ

Resets are never optimum, but they are a necessity in my work.?ÿ ?ÿSimply put I am forced to rely upon the work of others that may (or may not) be of questionable quality.?ÿ I figure it requires a little bit of surveying, a little bit of math, and a little bit of luck.

As to whether the distances on a corner record are horz. or slope..it's up to you to figure it out.?ÿ A nail in a corner post some 30' distant from an obliterated corner that is also 15' higher than the corner location can make it difficult.

My expertise (or lack of) pivots on my knowledge of the surveyor whose work I'm following.?ÿ We get glimpses of each other from time to time.?ÿ The other day I saw a crew out in the intersection referencing a corner.?ÿ I had to stop and say howdy.?ÿ I noticed the PC had a FB and a roll-up tape for the task.

Now were their ties horizontal or slope??ÿ Who knows??ÿ But out of the two guys I didn't see a plumb bob one on anybody's waist.

All you can do is reset a corner from ties to the best of your ability...and then check everything you can.

@paden-cash and let the beatings commence.?ÿ Lol

"section corner that has most likely been destroyed after the road was repaved"

I'm sure you mean the monument for the corner was destroyed when the road was repaved. Or was it? Appears to be an overlay. Unless you have sufficient evidence to prove the overlay tore out all previous monuments there may be reason to dig up the fresh surfacing. The road authority should have transit tied the monument before the road work. I have been known to dig through fresh overlay to recover the mark. When the construction engineer gripes I have to pull the code that requires the road authority to preserve the mark and reset it. A17 yr?ÿ old CCR don't cut it. Anyone remember what a transit tie is? For starters its not a RTK tie and its still the best way to preserve a location.?ÿ

Posted by: @paden-cash

I figure it requires a little bit of surveying, a little bit of math, and a little bit of luck.

And a healthy dose of some strange thing called "common sense".?ÿ ?????ÿ