In trying to properly re-establish corners of a railroad block which was established in the 1800s by an "office survey", I will need to tie in original corners of adjoining blocks that are 23 miles apart east to west and 14 miles north to south.
Each square is 1 mile and the traverse looking line connects the NGS tri stations within the limits of the project.
I don't think I have ever covered such a large area in one survey. 322 square miles. I am sure at such a distance there are some issues I am not thinking about. I have done work in the area based on other's secondary monumentation but I would like to tie the original controlling corners to check against as wellas to have for future work in this block (which covers about a 1/4 of one whole county and part of another county). GPS should make it a breeze compared to past efforts. I suppose I am looking for suggestions or recommendations on handling such a large area project.
[moved to Land Surveying category]
For jobs like this, I like to control my network via opus. Don't worry about transferring control from base to base, just submit to opus.
If you don't begin on the surface and stay there, or begin on the grid and stay there, you're asking for problems. Scale factorsmwont hurt nearly as bad as convergence.
You already knew that though. There is no difference between your project now and working inside a city block, just bigger so attack the big one same as the little one.
Once you have located to your best efforts the original rail road block, what are you going to do with the data. Does local improvements and occupation all done in good faith trump your efforts? Unless the Block is still intact as a block I don't see much value in what you propose to do, but I am not there with the knowledge you have. So I are curious.
jud
Think of the block as a township and each survey in it a section. Many of the sections in the area aren't occupied.
Andy practices in one of the few areas in Texas where proportion of original surveys is permissible as even though each section is its own survey with patent, simultaneous creation rules apply to the block as a whole.
That and probably 10 percent of the original corners were ever set.
Oh, definitely OPUS. I don't even think my radios will go far enough for RTK.
I admit that it is somewhat an academic exercise at this point. But regardless of occupation, the section corners are where the section corners are. Boney fried rice will not move them.
The lack of surveying did not keep the ranchers from settling and building fences. The fences are 200-300 feet off and most everyone knows it. I think Shell or Gulf came through in the 1930s and resurveyed the area and resolved the issues with the GLO. Having this stuff tied in to modern coordinates and CAD system will help us set up future surveys in the area. We'll still have to tie improvements and occupation, but no reason not to catch some of these original corners while they're still there and when I am out doing other work in the area (and when I say that, I mean anytime I drive more than a half hour south.)
If you look closely at the screen plot, you can see the original corner calculated positions around the perimeter of the work area. They are leadered out from the corners. The Commish ruled that even though the survey work was fraudulent/office survey, it could be located on the ground and you have to hold the controlling corners as called for in the field notes. It amazes me that such a large area is controlled by so few corners. And as Chris said, usually only block corners were set. Rare for interior section corners to get placed.
> In trying to properly re-establish corners of a railroad block which was established in the 1800s by an "office survey", I will need to tie in original corners of adjoining blocks that are 23 miles apart east to west and 14 miles north to south.
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> I suppose I am looking for suggestions or recommendations on handling such a large area project.
Well, I'm not sure whether you're asking about the mechanics of actually making the tie or of deciding which monuments you'll need to tie.
If it's the former, naturally static GPS is the way to go. Depending upon how many receivers you have available, you could leave one running on some central base point that you already have positioned and, when you get to an area set another point to begin running a receiver on while you hunt for the monuments that you'll need in the area. If you plan to leave a dual-frequency receiver on a particular control point near the area of your survey for at least four hours, then OPUS ui a viable alternative, although personally I'd prefer to have two independent OPUS solutions on two different days to rely upon, but one day's solution would work if the statistics are good and the session is at least four hours.
As for which monuments to tie in, let me tell you the cautionary tale of a well-known surveyor, no longer among the living, who thought he could just tie in a handful of original corners that could be proven as such and recalculate the entire block from them, disregarding all other evidence of what one would logically conclude was that of the original survey, just without bearing trees or topo calls to support it. That surveyor identified one of the block corners incorrectly and proceeded to mistakenly locate every survey in the block under a construction based upon that erroneously identified corner. The rock mound that he thought had been placed in 1880 was actually built in about 1888 for a corner of a different block.
Each block will, of course have it's own specific history, but so much of that history is typically incompletely known that a prudent surveyor will start the research from scratch and satisfy himself or herself that the common assumptions that have been made about the block are actually supported by the facts.
