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survey tech

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Everything posted by survey tech

  1. For the historically inclined, their is an interesting story about the recent recovery and preservation of one of those original pre-1900 baselines, mentioned in the text on Dusty's page, this one being from 1848. Go to the POB magazine website, click on archives, type in "bodie island" in the search box, and the story will come up.
  2. JC1721 has a very thorough description and I would think it might not be too hard to reach, given permission to enter the property. I guess it must be the name of JC1722 that is causing you confusion. Its a point that was originally set as a section corner and later picked for geodetic use, probably because it occupies an especially valuable spot with good visibility. The name tells you its the northwest corner of section 36 in that particular township. Note that its description says its north-northeast of JC1721, which agrees with the data in that description, where it says that JC1721 is in the northeast quarter of section 35, which always lies directly west of section 36. In fact, the azimuth between the two is also given in the data, 24 degrees 50 minutes east of north, so it should be fairly easy to visualize the relationship of the two points on the ground.
  3. For those who are interested, theres a lot to learn, and its all really pretty engrossing once you tackle it. The ACSM is the foremost authority on the subject and their manual of defintions includes for example: 23 definitions of "station" 39 definitions of "angle" 42 definitions of "line" 44 definitions of "survey" 51 definitions of "map" So theres always plenty of room for confusion. My fellow elitists and other technical mavens may want to visit www.acsm.net to check it all out for themselves.
  4. Yes, thats the difference in purpose between geodetic and cadastral. The difference in placement is that cadastral markers, nearly all of which are corners of properties, are placed at a specific location, while geodetic markers are placed at random, wherever they may be most useful. The original reason for the creation of a national database of geodetic points was to facilitate the development of the country through interstate commerce, which is why the NGS is part of the Commerce Department. The Interior Department has a very different mission, the administration of public land. The BLM has jurisdiction over literally millions of points in the 30 public land states, many many times more than all those ever documented to NGS standards for geodetic purposes.
  5. I would guess DMATC-GSS may stand for Defense Mapping Agency Traverse Control - Geodetic Survey Station, or something to that effect. I would imagine it must be near some military installation. The GLO was the federal agency in charge of the public lands before it was replaced by the BLM, shortly after WWII, so any GLO markers are also cadastral rather than geodetic, which means that information pertaining to them will usually be found in property boundary records stored in state offices and county courthouses, rather than in a national database.
  6. The Interior Department markers in the eastern part of the country are usually found along the boundary of a National Park. They are far more numerous in the west, where, unlike the east, the vast majority of land remains federal property. Technically, they are cadastral markers, not geodetic markers, and they have no connection to defense, which is an entirely separate department.
  7. I would bet that you will find at least the remains of some of them, but they may be in some very hard to reach, and even dangerous, places.
  8. Dusty For what its worth, those thin witness posts are actually fiberglass or plastic, which is to provide flexibility, so they give and spring back when hit, instead of just getting knocked down, run over and mangled as the old metal style often did. Also HARN stands for high accuracy reference network, meaning that the point is part of a modern network adjustment and therefore represents state-of-the-art accuracy.
  9. Thanks for the guidance 6T, I guess I was so busy answering those 300 questions that behaving like an elitist just slipped my mind for a while.
  10. As you probably know, some colleges and universities have very extensive engineering programs, while others have few if any, so some campuses will have a lot of markers while others may have none. Some of the very best programs are at small schools in out of the way places like Big Rapids Michigan, Carbondale Illinois, Lehman Pennsylvania, Kalispell Montana, Johnson City Tennessee, and Marietta Georgia.
  11. The CWA (Civilian Work Administration) was a depression era government project to employ the poor and reduce the breadlines. It was one of many such programs that were part of President Roosevelts New Deal policy, along with the WPA (Work Progress Administration) and CCC (Civilian Conservation Corps), which my father joined to escape the desperation of rural poverty in Eastern Kentucky. They did a tremendous amount of surveying, mostly in the midwest. In most areas they worked sunup to sundown for $1 a day plus room and board. These people did an outstanding job, under the circumstances. There is a wonderful monument to them here in Georgia, on Pine Mountain, near Warm Springs, where the President died. Its something we can all do well to think about when we start to feel that we have it rough today.
  12. The witness posts make very easy targets for vandals. In rural areas, especially in the west, they are often found full of bullet holes or shot to pieces, after being used for target practice. It has been realized that replacing them amounts to placing fresh targets for the trigger happy types, and is thus considered pointless. It has been determined that in such areas, sadly, a point that is unmarked, and therefore unobserved, is far more likely to survive.
  13. I'm waiting for someone to provide me with a definition of the word "elitist". After all, it would be so very much trouble to have to look it up in that great big dictionary for myself.....
  14. There are magnetic observation stations all over the world, where a magnetometer is used to measure the earths constantly changing magnetic field and magnetosphere. NGS once had a program called the geomagnetism project, but I think it has been replaced by more modern programs. The cluster of markers of different kinds in one small area is fairly common for research and training facilities such as universities, where students of engineering and geodesy use them to practice.
  15. Looks like all the leveling in Rogers County was done in the thirties, so you are not likely to have much luck with those. However, there are several USGS tri-stations set in 1968 and a few older ones, most of which have several recovery notes, so you will likely have a better chance going for those. Pilant, for example, looks like it may be the easiest, since the last recovery note says that the land owner has agreed to protect it. Milan, on the other hand, is an example of one that has been classified as destroyed on the basis of the personal knowledge and testimony of the land owner. You can use the search-by-county feature at NGS to review them all at once.
  16. There does not appear to be any marking on the cap indicating that it is a survey marker. Since both the type of object and the location are at odds with the description, I think what you have there is a sewer cleanout. Look again, more closely, in the spot specified by the description and ignore the coordinates.
  17. BDT I doubt there are more than a few thousand, probably less than 1% of the total, they are nearly unheard of in developed areas, where they have usually already been weeded out to avoid annoyance.
  18. Actually, this is an example of a point that was not even intended to be reused. The name, TP 1 226 A, gives you a clue about this. TP can stand for traverse point, turning point or temporary point, but in any case, its normally going to be a minor point used only to get from one place to another. In this case, it appears to have been part of a USGS traverse. I would guess that it was probably just a nail stuck in the ground. The fact that they did not bother to set a proper monument illustrates the fact that they considered this spot to be of little value and/or not likely to survive for long. Its likely that it only appears in the NGS database because it was part of a traverse run between important points and therefore it got adjusted along with those points. If the point is in a remote area, it may have been included simply because they decided it was better to have any kind of point listed in that area rather than nothing. Rarely, points of this kind may be improved and properly monumented at a later time, but at least 99% are never recovered and disappear within a short time.
  19. I hope you enjoy technical reading. Visit the National Geodetic Survey website and dig in.
  20. First of all, there are 11 stations listed under "mesquite" in the NGS index, in Texas alone, so there is plenty of room for confusion. Only 7 of them have datasheets, only 5 of them are involved in this case, and only 3 of those have datasheets. Generally, anytime a disk is stamped with more than one date, it has been reset, though "reset" is sometimes also stamped on it, and sometimes not. Looking at the NGS datasheets in detail, it becomes pretty clear what happened here, although it is not spelled out and has even been masked by the removal of some of the data. The original mesquite was set in 1947, apparently as a triangulation station, since only tri-stations have reference marks. In 1969, it was reset, presumably near its original position, probably after being discovered laying on the ground. At that time, it no longer had any value as a tri-station, so its original datasheet and PID were retired, and it became CS1403. Also at that time, each of its 3 reference marks got PIDs (CS1404-1406). There is no definite indication of whether or not the reference marks were actually reset, or merely restamped with the 1969 date. There is no way of telling for sure, since the original 1947 data, which would have given the exact relationship between the four points, is gone. Anyway, as of 1969, the tri-station and its reference marks officially no longer existed. They were now simply 4 separate benchmarks that happen to be close together. The lat/long given is the same for all of them and is not exact because they are now vertical control points, not horizontal control points. Note that they all have different elevations, which are exact. The lesson to be learned, for anyone interested, is to pay close attention to all of the relevant data available, as well as all of the stamping, in order to avoid this kind of confusion and the resulting errors.
  21. Some lids are of the type that can simply be lifted up, like a standard water valve cover, but in recent years more have been installed that require a socket wrench, allen wrench or similar tool to open properly. Prying them off is not advisable, since it will usually make it impossible to put the lid back on properly, effectively destroying it. Also be aware that roaches, spiders, snakes and scorpions find these dark holes quite comfortable and are commonly found in there too.
  22. Thats an excellent example. In most of the midwest, its very easy to mavigate using the rectangular system, since nearly all county roads and local arterial roads run along section lines and nearly all major intersections, outside cities, are at section corners.
  23. BD You have it right, except that I would say the NGS database has been growing cobwebs for at least 30 years. As several people here have noticed, the volume of recovery notes peaked between 1920-1960 and faded out during the 1960s. I think there have been less recovery notes submitted in the last 30 years than in any 10 year period prior to that time. As you supposed, this is not really a problem since local surveyors generally know where the markers in their area are. Construction workers not only fail to document the points they destroy, they typically try to hide what happened, if they even notice it. In most cases though, they are unaware that they even destroyed anything. Its really up to surveyors to keep track of the points that can be saved and protect them when possible, which they do.
  24. If what you found does not exactly match the description, it will nearly always turn out to be a different point that merely happens to be in very nearly the same place.
  25. They are not so sacred that they can be allowed to prevent progress. The whole reason they were set was to facilitate progress. In fact, there have been cases of deliberate destruction, albeit futile, perpetrated by environmental extremists, seeking to prevent, hamper or delay development in specific areas. Only those markers that were placed in the most wisely chosen spots were able to survive for a very long time. The concensus among professionals today is that there is little or no need to report destruction, or finding for that matter, to NGS, since a marker in any given locality is of no use to those in other parts of the country. The markers are jealously guarded and thoroughly documented by the states, counties and cities which they serve. Remember, the markers do not belong to NGS. They belong to the citizens of the communities in which they exist, and those people, especially the surveyors and engineers, who need them the most, are expected to preserve and maintain them or suffer the consequences of laying them to waste. If you have some reason to believe that markers are being destroyed or damaged through negligence in your area, this may be a matter that should be brought to the attention of your city council or other local authorities.
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