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What are these different types of benchmarks for?


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We're having fun finding these things, but it would be more fun to know what they are all for. Obviously, benchmarks are for locating other things such as new building sites, property lines, etc., but there are so many types with possibly very different uses, and I was hoping some of our professional representatives or someone could define the types of benchmarks.

 

"Marker type"; , triangulation station, vertical control disk, horizontal control disk, traverse station disk, topographic station disk, tidal station disk, bench mark disk, survey disk, calibration base line disk. Surely some of these are just synonyms, but not all. Can someone define these different types - what they are used for?

 

Within the descriptions of the PIDs are these further types:

station, azimuth mark, reference mark, underground disk, surface disk. What are all these for? I know what an azimuth is (a bearing), but how is an azimuth disk different from the (main) station disk? If the (main) station disk is gone, do survyors use one of the reference marks or the azimuth mark instead, or is the whole PID useless at that point?

 

Are the underground station disks dug up often? (Some are quite deep.) Various whole PIDs are buried a foot deep or more. How do surveyors find these when they need them? Metal detector? Accurate traverses from a reference mark?

 

Of course, there's also a big array of different physical markers other than the typical disk: standpipe, tank, cupola, gable, chimney, church steeple, grain elevator, metal rod, chiseled square, chiseled cross, radio/tv mast, lookout tower, pipe cap, bolt, spike, flagpole, stack, microwave tower, airport beacon, navigation light, lighthouse, etc. etc. (just figured I'd get an entertaining little collection here after my questions)

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I had to get the book out on this one.Task Commission on the status of Surveying and Mapping,the Society of Civil Engineers in 1959 declared 4 major categories. 1. Land Surveying 2. Engineering Surveying 3. Geodetic Surveying 4. Cartographic Surveying. Surveying Agencies, (a) U.S. Geological Survey. This org. est. 1879, is charged with the responsibility for preparing then National Topographic Map Series covering the United States and it's outlying areas. (:) U.S. Coast and Geodetic Survey. This Bureau of the Enviromental Science Service Administration,ESSA, 160 years of service in 1967.Publishes nautical charts of Coastal waters of the U.S. and territorial possesions,executes the Principal geodetic surveys of the country, and prpares and distributes the aeronautical charts needed by American civil aviation. President Thomas Jefferson and Ferdinand Hassler, noted scientist, were founders of the Coast Survey. © U.S. Naval Oceeanographic Office. This agency performs essentially the same hydrographic charting functions of the Coast and Geodetic Survey but with respect to waters not contiguos to the U.S. and it's possesions. (d) U.S. Lake Survey. This is the nautical charting agency of the Corps of Engineers. It is concerned primarily with the publication of navigational charts for the Great Lakes. (e)U.S. Bureau of Land Management. This orginazation is responsible for surveys of the Public Domain. Rectangular public surveys are still being executed in some of the western states and in Alaska. (f) U.S. Corps of Engineers (U.S. Army). Each army engineer district office has a survey section that performs many kinds of surveying tasks associated with the control of navigable waters over which the Corps has jurisdiction. (g) U.S. Bureau of Reclamation. The extensive construction program of this org. involves many surveying tasks ranging from the preliminary mapping of a proposed resevoir to the layout of a large dam. Surveying Societies A number of technical and professional societies have been organized to advance the science and art of surveying and mapping in their variuos branches. They include the American Congress on Surveying and mapping,American society of Photogrammetry, Surveying and Mapping Division of the American Society of Civil Eng., and numerous state land surveyor orgs. Registerd Land Surveyors ***. The high quality literature of these societies and their continued effort to improve the public image of both the pro engineer-surveyor and the licensed land surveyor have helped to elevate the status of the professional in this area of AMERICAN TECHNOLOGY. from, Fundamentals of Surveying, by W.H. Rayner,C.E.,M.S., M.O. Schmidt,Ph.D.

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Bench mark. A fixed reference point or object, more or less permanent in character, elevation of which is known. a bench mark may also be used as a turning point. in geodetic leveling based on the irregular surface associated with the geoid rather than the regular surface of a spheroid or an ellipsoid representing the surface of the earth. from, SURVEYING Theory and Practice, by Davis, Foote & Kelly I could go on all day with the defanitions,

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BDT

Some of your questions have been answered in earlier threads, but the extensive scope of what you are seeking to learn really goes way beyond what can be readily described in a forum such as this. Alot of what you are asking are things that are only learned over a long career. I suggest you make friends with a land surveyor or civil engineer in your area, who will be able to give you the most relevant and understandable answers, and perhaps show you some examples of the different kinds of points in your area. The only alternative to this would be many hours of technical reading.

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An azimuth mark is a point established in a precise known direction, which provides your local surveyor with a handy reference line, when used in tandem with the tri-station. They are also very handy for astronomy hobbyists, who can use that reference line to orient a telescope, when trying to find a particular star, galaxy, quasar, nebula, etc. at a known location in the heavens.

 

Just go to your favorite book site and do a search for "geodesy", "triangulation", "land surveying", etc. The NOAA online library also has an extensive listing of highly technical articles and treatises chronicling the development of the science over the last 200 years.

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