How far away is acceptable for a witness device?

Anything over 100 feet is too far. Period. There are too many easy ways to find a way to keep them fairly close, yet out of the way of expected disturbance in the next few years. A fairly common practice is the setting of bars in the ground where they cannot possibly be assumed to be anything but a reference bar, if found accidentally.

The greatest acceptable distance is 149.4532755753 feet.

"Pull" ties, as I call them, 100' or less, are nice. Resetting or checking a corner from references with a chain is a good reason for me to keep one in the truck. I had the roll-up plastic or fiberglass tapes, they eventually stretch.

I've ran into a pickle a couple of times up in the panhandle with rebar "pins" as references. I was following an ODOT survey that had set 1/4 corners and section corners north and south of an east-west highway alignment (on a section line). At each land corner, his references were pins offset @ 50', 100' and 150'...but he ran them 90å¡ to the N-S section line. Usually not a problem...until you're in a part of the country that is green March wheat as far as you can see in every direction. No topography whatsoever. No windrows from plow or fence (that was never there), no posts; just wheat...and the wind. This was part of a sixty square mile "Whitlaw Ranch" if I remember right. So when you finally get to where you THINK you might find a section corner...did you find the corner, or just one of the references?

In that particular instance a bearing and distance tie to an adjoining land corner (S01å¡47'15"W, 2647.44') would have been a nice thing to have!

I don't think distance is as important as making it clear and simple for the next guy to follow. if a bridge 2 miles away is the best chance at reproducing the original then great. distance is fairly easy to measure these days.

Nate The Surveyor, post: 366122, member: 291 wrote:
S 78*18'31" W 5678.99' to an alum. Disc in SW headwall of bridge, over Fourche Lafave river relief
Nate

S 78*18'31" W direction is pretty useless with a GPs tie. Plus who's aluminum disk?

Paul in PA

Paul in PA,
It would be extremely useful, if the next guy, who needed it, understood his equipment, and had your metadata.
Arkansas Hwy. Dpt set alum disks in concrete, on most new constructed bridges.

Reference points should not require the use of GPS gear. This goes back to the thread on what it takes to start out in a business. Dictating that everyone must be able to afford survey quality GPS simply to find a reference point sure doesn't help out the otherwise highly skilled professional who doesn't have the bucks to buy in.

Nate The Surveyor, post: 366122, member: 291 wrote: All this talk about fence corners, as monuments, and adding some sort of survey marker, whatever sort, has got me thinking...

The key elements are (a) whether the site is GPSable, (b) what the relative uncertainty of the tie is, (c) what the practical difficulties are of some intelligent non-surveyor (that would include some landowners) using the tie to the reference mark to locate the corner in question for some practical purpose, and (d) what the practical difficulties are of some future surveyor using the tie to the reference mark to confirm or reestablish the location of the corner in question for all purposes.

With the price point of Javad, and the performance, and education the newly licenced persons, I'd expect many new folks to participate. One person that I mentored some, and is now licensed, bought a new Topcon hiper GPS, and robot, in his first few months of business. It's the up an coming way of things. Right now, you can get a used hiper on eBay for 10 K or less. The world is changing fast. (Enter "grandpa" by the Judds) I hate spell check. Its my words enema sometimes.

There is a heirarchy for reference marks and witness stakes. From best to least, I think it would go like this:

(a) intelligent layman with 25 ft. tape can locate corner for purposes of ordinary construction from markers provided,
(b) surveyor and assistant can locate corner with certainty using tape in less than 15 minutes,
(c) surveyor can locate corner with total station from one setup with certainty in less than 30 minutes,
(d) surveyor can locate corner by some means with certainty in less than two hours, or
(e) surveyor can only locate corner with certainty by level of effort amounting to some significant fraction of effort required to resurvey boundary of tract.

While such a standard may be nice, that sounds a bit like 1st McMillan, chapter 97, verse 192.
Also, such a witness (as I mentioned) would survive, if construction, or activities threatened.

To blatantly state that any distance is to long is just closed minded.

Every situation is different, and the surveyor's responsibility is to place it as close as conveniently possible, as well as make it obvious to the layperson that it is a witness corner.

Last week, my field crews set a witness at 171'. (Sorry holy cow.) the witness was to a 1910 meander corner(long gone) set at the edge of the river (sec cor falls in river) the 171' between the crew and the MC is a flood plain, covered in water seasonally.

Nate The Surveyor, post: 366151, member: 291 wrote: Also, such a witness (as I mentioned) would survive, if construction, or activities threatened.

The remote reference monument is basically a means of last resort. I mean, there is always the CORS network, right? But when overhead cost of time is measured in hours, instead of a few minutes, it ain't a reference monument in the sense I would ordinarily consider to be my first choice.

Really, the whole test of reference marks should be who can locate a corner from them and what level of effort will be needed to do it.

Good catch, summerprophet. I should amend my comment to state that in the general case a distance of 100 feet or less is preferred. That goes to being able to do a quick and dirty, one man tape pulling to rough in the location of the monument from a couple of the references within a few minutes.

I have cussed many an old timer for selecting references that were far too close to the monument because of the fact they would all be destroyed by the project for which the monument was needed. Highway projects are famous for that foolishness. On a six-mile road project several years ago we had two sets of references for every monument. One set were all easily taped to places just outside the assumed construction zone. The second set were all further out and very easy to shoot with a total station from several convenient set up areas just in case the final road design expanded the expected construction zone significantly.

Sadly, one survey company regularly doing highway projects currently have gone to setting reference bars over 1000 feet from the subject monument. Multiple set ups are required to tie all of them to the monument. That is not the least bit helpful. In nearly every case, references could have been placed within a 100 foot radius of the monument for rapid, simple recovery.

A witness can be any distance or direction that can be used repeatedly to find or relocate the monument it is a reference witness of within the realm of tolerance expected.
I have no problem using a hand compass to locate a tree within 25ft and would not begin to attempt that method at 200ft.
Trees are wonderful witness, around here it is better to choose a trash tree that is not harvested for money or its material need.
Power poles and culvert headwalls are better because on the last tree harvest, nothing is spared.
An old tree that casts a big canopy prevents the growth of many money trees, especially an entire boundary of them.
A few years ago the only certain remains of the location of a property were the location of two bridge abutments that were shown in detail in their relation of the boundary on the original 1905 drawing.
Witness needs to be located by a means that do not require some rare and elaborate method to use. For example, it should not be something that would take an epic Indiana Jones journey to retrace.
The worst deed I've had to follow had no witness or distance to another monument and started out "beginning at the waters edge of Caddo Lake". Had they witnessed a tree, it would have been a Cypress and that would have required a mark some 12 to 15 ft above ground level and maintained to survive the amount of time that had passed.
In comparison, a year ago at the seminar at Caddo Lake we were fairly certain of a Cypress witness to a mile marker some 273ft away.
At the time of it being referenced, it was probably the closest tree. Distance was within a vara and direction using Compass app on my phone was within a degree.
Some witness choices are better than others and any are usually better than none as long as they are relevant to the survey made on the property.
:plumbbob:

To date, my longest witness trees, are 400 ft and over a quarter mile. Shot in with total station, with nails On the side. I put DOT tape on them, and shot them with a Leica reflectorless inst.

It wasn't a reference but the point of beginning that was my worst ever circumstance. They began at the center of the east end of the county road bridge. That would be the bridge that was there in 1914. You know, the one they replaced in about 1916 which was then replaced in 1978 by a very nice, very big concrete bridge installed after channel straightening and widening had occurred. The east end of that bridge was on the order of 50 feet further east.

Rule of thumb for a witness's is 5 chains or less; a witness monument is on line, a reference monument is off line.

I would consider one on a random line a mile away to be a control point. No harm showing it, but wouldn't classify it as a witness.

We can't expect all surveyors to use GPS, I know a number of them that are really good and they are using instruments, never have moved over to GPS equipment.

So to be useful for them a control point needs to be able to be occupied, have a backsight, best to have at least two and some kinda expectation that it can be used in a traverse.

In other words a CORS point isn't very useful that way.

I personally think that reference monuments "should" be placed along the property lines to provide synergy for the landowner and surveyor. That being said, I've seen MANY old calls for witness trees in Navarro County that were SEVERAL hundred feet away. Primarily because there were no other objects and it was before the industry had taken to setting iron stakes.

That being said, I like them on line, and under 50' unless they are witness trees in which case, I still like them under 50', preferably 25' with the notation to either the face or the center. That way I can reconstruct them in the field, with a tape, with a level of confidence under 0.2', and if need be, reset the monument from them.