Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 65
6
Conclusions
One of the powerful forces steering the development of information systems
is the heuristic power potential of spatial analysis. Even the limited experience
to date of overlaying data layers and analyzing spatial interrelationships
among these data layers has aroused high expectations. The technology to
perform this work is already available at ever-decreasing costs. The emerging
technology of precise positioning promises to provide the coordinates needed
to link data layers within these systems in the near future. Such geographic
information systems encompass many large, coordinate-based data files.
It has become painfully apparent that the application of spatial analysis to
the diverse and complex tasks of managing federal land resources has been
much delayed. One major factor accounting for this delay is the nature of the
cadastral surveying tradition in the United States, which places high value on
boundary monuments and locally referenced survey measurements and little
or no value on coordinate-based reference points connected to the national
geodetic network.
The federal cadastral interests are defined by the Public Land Survey Sys-
tem (PLSS) and the township, section, and quarter-section corners. These
interests are recognized to be large and complex because of the extensive
areas of federal land ownership, the vast resources, and the often complex
spatial pattern of fractured rights and easements. Close examination of the
federal interests reveals a complex spatial pattern at the interface between
federal and nonfederal lands. The interspersion of private holdings within
federal lands contributes to this complexity.
The Committee realized that the prospects of integrating land records
65
OCR for page 66
66 MODERNIZATION OF THE PUBLIC LAND SURVEY SYSTEM
contained in federal topographic, geodetic, and cadastral files were unlikely
as long as cadastral records and data lacked a coordinate basis in the PLSS
areas. The Commiteee recognizes the PLSS as a national resource of immense
importance that needs to be preserved to protect property ownership rights in
federally owned areas, along the federal-private interface, and on patented
lands. The present condition of the PLSS iS poor, and deterioration continues
to diminish the condition of the system. Efforts to maintain the system have
low priority virtually everywhere. Vigorous steps to restore and maintain the
PLSS are needed.
The Department of the Interior should clarify the responsibilities for
Public Land Survey System (PLSSJ maintenance. The Commitee recommends
that the Department conduct investigations into the present condition and
future role of the PLSS. This should include a review of federal law and
authorities, state and local law and authorities, the condition of PLSS records
within state and local government, and state and local programs and private
and semipublic activities affecting modernization of the PLSS.
The goals of the multipurpose cadastre and the concommitant tasks of
integrating spatial data files led the Committee to conclude that a program is
needed that goes well beyond mere maintenance to include modernization of
the PASS. This modernization program would take full advantage of the
accuracy achievements together with the time and cost economies of the
emerging positioning technology to establish precise coordinates for monu-
mented PLSS corners. These corners would then be integrated into the
national horizontal control network. The Bureau of Land Management (BLM)
is urged to change priorities, procedures, and standards to establish coordi-
nates that meet recommended multipurpose cadastre standards for corners on
federal-private interface lands. Over time this would ensure that the survey
work that needed to be done in any case would have additional utility because
it met multipurpose cadastre recommended standards. These same standards
and practices extended to all federally funded survey projects would further
advance progress toward the multipurpose cadastre.
The Committee recognized a need to develop a PLSS digital coordinate file
to serve a variety of present and potential needs. This file could encompass
PLSS section corner locations that meet positional standards defined by
National Map Accuracy Standards extractable at modest cost from the
National Cartographic Data Base. In fact, the National Mapping Division is
currently including a PASS data layer as part of the Digital Line Graph file
development. The need for such data for purposes of display and spatial
analysis is already evident and can be expected to grow as interest in geo-
graphic information systems expands. Over time, this PASS file would ac-
cumulate coordinates of progressively higher quality and thus support the
multipurpose cadastre effort.
OCR for page 67
Conclusions
67
Demand for PLSS coordinate data could only be assessed in a preliminary
way. At the coarse end of the position accuracy spectrum there is clear evi-
dence of demand, chiefly among users involved in linking natural-resource
records to base maps for purposes of spatial analysis. Their accuracy needs
are satisfied by the National Map Accuracy Standards governing the con-
struction of the National Cartographic Data Base. At the fine end of this
positional accuracy spectrum, on the other hand, are the federal program
managers who require clear spatial definition of their areas of responsibility.
The present lack of jurisdictional clarity is a costly drain on program resources
and time. This federal user group is merely a subset of the client group en-
visaged for the national multipurpose cadastre. It is curious that no user
group was identified for intermediate positional accuracy standards. This
broad gap might well reflect the paucity of base maps and resource inven-
tories between the 1:24,000 scale used for the 7.5-minute topographic series
and the fragmentary local surveys at cadastral scales.
The Committee recommends that responsibility for establishing and main-
taining a national digital coordinate Public Land Survey System (PLssJ data
base be placed with the Bureau of Land Management in cooperation with the
National Geodetic Survey. This file should include data on the source and
estimated accuracy of each position. We recommend that the Office of Land
Information Systems, proposed in the report Need for a Multipurpose Cadas-
tre (Committee on Geodesy, 1980J, be established in each state and be re-
sponsible for maintaining a file of PLSS corner coordinates determined by
state or local units according to national standards established by the Bureau
of Land Management. We recommend that the Department of the Interior
develop mechanisms whereby private and semipublic units can contribute
PLSS corner coordinate data to the file maintained by the proposed State
Offices of Land Information Systems.
To facilitate the task of integrating spatial data files, the Committee rec-
ommends that the Department of the Interior report on the positional ac-
curacies of all PLSS corners and on the positional accuracies and spatial
resolution of all their resource inventory files. We recommend that the
Cadastral Survey Division of the Bureau of Land Management express survey
results in terms of point accuracies as well as closures. We also recommend
that all agencies contributing data to the PrSS digital coordinate data base
assess and maintain records on the unit cost and accuracy of the coordinates
they derive.
Representative terms from entire chapter:
public land
