Modernization of the Public Land Survey System (1982) / Chapter Skim
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Pages 26-51
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From page 26... ...
Multipurpose cadastre activities at local government levels that involve the digitization of the PLSS corners are listed in Appendix A 3.3.2 The Private Sector A problem encountered by many energy companies operating in the western United States is the integration of seismic, geologic, and leasing information.
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c 1 1 4-c ~ o en I]
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3.4 DEMAND FOR A DIGITAL PUBLIC LAND SURVEY SYSTEM DATA BASE Although the scope of this study did not include a broad investigation of demand for coordinates of PLSS comers in digital format,it is clear that a substantial demand exists in some user classes for a coordinate-based version of the PLSS. Organizations in the private sector have been creating a digital version of the PLSS that is characterized by extensive are al coverage, relatively high density (section corner plus irregular section boundary)
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From page 29... ...
Similarly, from discussions with officials of the state of Montana it is estimated that their data set is less accurate than the one created by Phillips Petroleum. Nevertheless, these data bases are being used, and used extensively, by many nonfederal organizations that are apparently satisfied with the accuracies provided by the procedures that they have adopted.
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There are similarities to the national geodetic network developed by the National Geodetic Survey and its predecessors in placing monuments for horizontal geodetic control. These .
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The relative accuracy for Third Order, Class I, is 1 :10,000 and for Second Order, Class II, it is 1:20,000 (Federal Geodetic Control Committee, 1974, 1976~. At half-mile spacing, this requires that, to meet Third Order, Class I, specifications, the position of each corner should be accurate to a standard deviation of +0.19 ft and to meet Second Order, Class II, to +0.09 ft.
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From page 33... ...
The locations of these corners may be expressed in one of the three reference systems shown on the maps: latitudelongitude, Universal Transverse Mercator, or State Plane Coordinates. Measurements are made either in a manual mode utilizing only a scale or, much more commonly, by using one of the many computer-assisted digitizing systems.
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From page 34... ...
. 4.1.3 Acquisition of Coordinates from Archival Survey Data in the Bureau of Land Management and Other Repositories "Standard procedures and specifications" for performing PLSS surveys have existed for over a century.
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From page 35... ...
They could be treated as traverse data with closures being made between available geodetic control points, or they could be adjusted using an acceptable method. 4.1.3.1 Computation of Coordinates from Archival Data Using Traverse Reduction Methods Every modern survey office has one or more computerized traverse reduction routines.
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There is no more apparent reason to recommend retrieving and adjusting the old traverse data than there would be to recommend retrieving and computing by the traverse method discussed. Although at this stage there is no recommendation to retrieve and process all the archival data, the possibility of retrieving selected sections of them is discussed in Section 4.4.
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From page 39... ...
4.2.2 Mixed Technologies 4.2.2.1 Mixed Technology I: Geodetic and Land-Survey Methods With mixed geodetic and land-survey technology, the geodetic ties to the outside corners of each township are made by geodetic methods and the internal ties to the section corners are made using land-survey methods. In other words, the ties between township corners are those that would be done in retracement or resurvey of the section lines for boundary definition purposes.
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From page 40... ...
On the assumption that these points should be adequate for controlling large-scale maps, be they topographic or cadastral, i.e., as a foundation for a multipurpose cadastre, an accuracy of at least 1:10,000 would be required. Thus, presumably some increase in cost would be involved, although the general state of the art is such that any one of the following methods is capable of giving closures of 1:10,000 as required for Third Order, Class I: conventional, electronic traverse using the Zeiss Elta 2 satellite Doppler point positioning using Magnavox MX1502, and inertial.
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From page 41... ...
report the development of instruments based on the interferometric principle using GPS satellites, which give accuracies to 0.1 ft rapidly and at a projected modest cost. A merit of this technology is that it would be suitable for occupying section corners without any further densification of the primary geodetic network being required.
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From page 42... ...
From this it is apparent that there are two emerging user groups, widely separated on the necessary accuracy with respect to PLSS coordinates. This study did not identify a significant user group for PLSS coordinate data between the multipurpose cadastre requirements and the 40-ft accuracy range.
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From page 43... ...
This activity, in itself, will go a long way toward maintaining this valuable national resource—the Public Land Survey System. Noting that the Bureau of Land Management (ELMS is using potentially precise instrumentation to establish the positions of PLSS corners, it is recommended that BLM determine these positions with sufficient accuracy to serve as control for the multipurpose cadastre.
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From page 44... ...
2. The Bureau of Land Management and other agencies and property owners responsible for property abuttingsection lines should ensure that all section corners and quarter-section comers on their boundary be monumented with monumentation equivalent to or better than that specified for Third-Order Control monumentation.
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, the Public Land Survey System (PLSS) , and geodetic data.
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The digital cartography program addresses applications of digital technology in cartography and geography. It is focused on the development of a national digital cartographic and geographic data base (Southard, 1980~.
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This geographic consistency is of particular importance to those states that are largely in a patented status and also do not anticipate any major federal land acquisition activity. It is recommended that the National Mapping Division (1J accelerate the development of digital files of the 7.S-minute mapping series and (2J provide documentation of the current status, cost, and methods and procedures being employed in the development of the National Digital Cartographic Data Base.
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even though owned and managed by other public or private owners (Wilcox, 1982~. This authority and the resultant cadastral process results in survey marks and defines legal boundaries of a tract of public land or between public and private land (interface lands)
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Legal property descriptions are required for the management of public land resources. Legal property descriptions are required for public land transfers, energy development, easement acquisition, timber sales, and grants of rightof-way, and these transactions depend on timely cadastral surveys (Wilcox, 1982~.
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2 Excludes trust properties Source: Inventory Report on Real Property Owned by the United States Throughout the World, published by General Services Administration. FIGURE 5.1 From Public Land Statistics, 1978, BLM, U.S.
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From page 51... ...
This should include review of federal law and authorities, state and local law and authorities, the condition of PLSS records within state and local governments, and state and local programs and private and semipublic activities affecting modernization of the PLSS. 5.1.3 Geodetic Positions Two national data bases have previously been discussed: the PLSS and the National Cartographic Data Base.
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