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surveying iii (topographic and geodetic surveys) - Modern Prepper

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The collection of terrain <strong>and</strong> climatic information. Arrangements for access to private or government property. The availability of billeting, mess, medical, maintenance, <strong>and</strong> other required support.2-40. Global Positioning System. Interreceiver visibility is not required for GPS <strong>surveying</strong>. Stationscan be set according to network design principles rather than traversing around buildings or mountains.The only requirement for receiving GPS signals is a clear view of the sky. Choose a station with noobstructions above an incline of 15° to 20°. Draw a station-obstruction diagram to assist in the planningof GPS sessions. Verify the station accessibility, draw maps with directions to the stations, <strong>and</strong> markeach station clearly. The field crew will be in a hurry to set up when they arrive, <strong>and</strong> unmarked stationscan waste valuable time.2-41. Triangulation. When the need to locate the position of a point that cannot be occupied arises, asin a special survey, triangulation is necessary. This technique makes special dem<strong>and</strong>s on thereconnaissance party. The mathematical computations place stringent requirements on the size <strong>and</strong>shape of the geometric figures that are used to determine coordinates. For this reason, the location of thestations will normally be dictated to the field-reconnaissance party, based on the results of the officereconnaissance. The reconnaissance party must ensure that the observation stations, which form thebaseline, are intervisible. A thorough knowledge of triangulation criteria is absolutely necessary.2-42. Traverse. The dem<strong>and</strong>s for a traverse reconnaissance are less stringent than for triangulation.Ensure that both the rear <strong>and</strong> forward stations are visible from each proposed station. Whereverpossible, distances between stations should be uniform. In control <strong>surveys</strong> that may become part of theUnited States National Control Network, the St<strong>and</strong>ards <strong>and</strong> Specifications for Geodetic ControlNetworks (SSGCN) must be satisfied. Spacing between stations is dependent on the available EDME.2-43. Electronic Distance-Measuring Equipment. An EDME traverse reconnaissance requiresintervisibility between stations. The minimum <strong>and</strong> maximum allowable distances are based on theEDME characteristics <strong>and</strong> the clearance above possible obstructions. Use of infrared EDME isdependent on the weather.2-44. Differential Leveling. Differential leveling should follow routes containing the least amount ofchange in elevation between BMs <strong>and</strong> individual setups. The routes frequently follow roads withmoderate traffic, so care must be taken to ensure the safety of the leveling party.2-45. Trigonometric Leveling. Trigonometric-leveling reconnaissance is performed during a traversereconnaissance. If possible, select a relatively level area2-23 EN0593

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