Identification_Information: Citation: Citation_Information: Originator: U.S. Dept. of Interior, Bureau of Land Management, Division of Support Services, Branch of Information Resource Management Publication_Date: 20080204 Title: Protracted Section Grid for Alaska (NAD83) Geospatial_Data_Presentation_Form: vector digital data Description: Abstract: Section boundaries were generated from geodetic latitude and longitude coordinate pairs as recorded on BLM's official protraction diagrams of the state of Alaska. The SDMS_PROD protraction tables were modified to include pro_pt83, section83, and township83. The latitude and longitude values in the pro_pt83 table were transformed from geographic NAD27 coordinates to geographic NAD83 coordinates using NADCON for Alaska. The Informix Section83 table is a spatially-enabled table that contains all of the protraction information for each of the 655,483 sections. Section shapes are stored as NAD83 geographic multipolygons. Each section was individually constructed from NAD83 geographic pro_pt (Protracted Point) table and is fully densified by including all township/section offset corners from adjacent township/sections. The geometry for a single section (i.e. SEC 1, T69S, R100E, CM) may include as many as 11 coordinate pairs on the exterior ring. The section83 table identifies 655,483 sections as 655,485 multi-polygons (two sections require two polygons each), as depicted on the official BLM protraction diagrams. MTRS Number of Geometries ----------------------------------------------------------- C033S066E27 2 C066S098E34 2 Purpose: For GIS mapping and analytical use. The spatially-enabled township table precisely maps the township coordinates as defined on the official BLM protraction diagrams. Not for use in determining area computations. Please consult official BLM protraction diagrams for the record protracted area. Supplemental_Information: The values used for this data were initially obtained from U.S., Department of the Interior, Bureau of Land Management, Alaska State Office, Division of Cadastral Survey and Geomatics's (BLM) AEH (acronym unknown) coordinate files. These files represented townships in two ways as follows: 1. Regular Townships were represented as a geodetic rectangle bounded by two latitudes and two longitudes. 2. Irregular Townships were represented as a sequential series of geodetic coordinate pairs. Additionally these files represented township subdivision by recording the origin point for township's subdivision as a code for one of the four township's corners and a series of codes indicating which rows and columns of sections were intended to be created. Collectively these codes are referred to as "shape codes." In 1996 BLM obtained an updated version of the AEH files from the State of Alaska, Department of Natural Resources (ADNR.) A comparison was performed between the most current set of BLM's files and ADNR's files. Lists of differences were compiled and resolved as follows: 1. Additional Townships The additional townships shown in ADNR's files were discarded as they represent marine townships and their creation and maintenance is not the responsibility of the BLM. One additional township shown in BLM's files was discarded as it represented land shown in another township that was properly represented. 2. Subdivision Shape Code Differences Referring to the official protraction diagrams the proper shape codes were utilized. Subdivision shape codes are implied on the official protraction diagrams as the township's graphic representation through the use of parenthetical distances. 3. OrthogonalTownship Boundary Position Differences Shown On Official Protraction Diagrams Referring to the official protraction diagrams the proper positions were utilized. Orthogonal township boundaries are shown on the official protraction diagrams as lines of true-mean-bearing along meridians of longitude and parallels of latitude. Reported on these diagrams are geodetic coordinates for the latitude and longitude for these lines. These coordinates are reported on the North American Datum 1927 (NAD27.) 4. Orthogonal Township Boundary Position Differences Not Shown On Official Protraction Diagrams Referring to the official protraction diagrams the proper positions were calculated and utilized. These positions were rounded to the nearest 1/1000 of a second for compatibility with adjacent townships. 5. L-shaped Irregular Townships These townships are "puzzle pieces" used along the intersection of meridians or for certain correctional meridians and/or parallels shown on the official protraction diagrams. No differences were noted between the two sets of files. 6. Alaskan-Canadian Irregular Townships Referring to the official protraction diagrams it was noted that neither BLM's or ADNR's files appeared to properly represent these townships. Therefore it was necessary to recompile these townships. Initially the townships represented in this manner were restricted to a portion along the international boundary in the southeastern panhandle of the State, specifically from the head of Tongass Passage to Mount St. Elias. Referring to the U.S., Department of State, International Boundary Commission (IBC) publication "JOINT REPORT UPON THE SURVEY AND DEMARCATION OF THE BOUNDARY BETWEEN CANADA AND THE UNITED STATES FROM TONGASS PASSAGE TO MOUNT ST. ELIAS, 1952" (IBC 1952) it was decided to represent those townships from the mouth of Tongass Passage to it's head as irregular townships. Further it was noted that Boundary Point 187 at the northern end of this portion of the international boundary recorded in the IBC 1952 publication was not on the 141st meridian. Referring to the IBC publication "JOINT REPORT UPON THE SURVEY AND DEMARCATION OF THE INTERNATIONAL BOUNDARY BETWEEN THE UNITED STATES AND CANADA ALONG THE 141ST MERIDIAN FROM THE ARCTIC OCEAN TO MOUNT ST. ELIAS, 1918" (IBC 1918) it was noted that the 141st meridian portion of the international boundary was recorded on the Yukon Datum at 141 degrees West longitude. Therefore it became necessary to additionally represent all of the townships along the 141st meridian as irregular townships. For the "southeastern" portion of the Alaskan-Canadian boundary (not including Boundary Point 187) the coordinate values used are reported in the IBC 1952 publication. These coordinates are reported on the North American Datum 1927 (NAD27.) For the "141st Meridian" portion of the Alaskan-Canadian boundary (including Boundary Point 187) the coordinate values reported in IBC 1918 publication are on the Yukon Datum. In order to get proper coordinates BLM contacted the IBC and a list of coordinates was obtained. These coordinates were reported on the National Geodetic Reference Datum of 1983 (NAD83.) These coordinates were further processed using the U.S., Department of Commerce, National Oceanic and Atmospheric Administration, National Geodetic Survey (NGS) computer program NADCON version 2.1 to obtain NAD27 coordinates. Intersections of the orthogonal township boundaries (true-mean-bearing) and the Alaskan-Canadian boundary (line-of-sight) were then computed and irregular townships were then constructed from the results. This process showed that one township adjacent to Tongass Passage, that had been represented as an orthogonal township falls completely in Canada. That township was discarded. Upon completion of this process GIS techniques were used to confirm that proper topology existed in this data. This process showed that in three localities a small parcel of land was shown in two townships. Referring to the official protraction diagrams it was decided to amend three of these diagrams and to construct three additional irregular townships. Additional analysis with BLM's Alaska Land Information System (ALIS) showed that a township had been surveyed that was not represented in this data. That township was added to this data as an orthogonal township. Township and Section Protraction Re-engineering: A. Added Section Table B. Add shapes to township and section tables: 1. Spatially-enable township, section, and pro_pt tables to include shape and objectid fields. a. Township shape field ST_Multipolygon b. Section shape field ST_Multipolgon c. Pro_pt shape field ST_Point d. Objectid set to not null, number (38) C. Add formatted MTR to township and section tables. C. Add land desc label field to township and section tables. D. Altered base protraction tables to: 1. Add fields to record the twp and sec pt labels, relative to the twp/sec being defined. Such as: NW, SW, SE, NE, IP, etc. 2. Add field to pro_pt to distinguish protraction points from construction points. 3. Associated the construction points to the appropriate twp/secs based on data in source data file. E. Updated the township features from ST_Multipolygon shapes consisting of only points at the township corners to ST_Multipolygon shapes also containing points of intersect where section lines meet the township boundary. 1. Densified the township shape features with section corners that fall along the twp lines. F. Determined all possible section corners for each township using explicit database relationships. G. Ran program that used Informix Spatial DataBlade and Java 2D framework to densify the boundary by determining the distance between each section corner and all township's boundaries; inserted any points within an extremely small tolerance (0.0000001 degrees) into the township ST_Multipolygon feature. About 1/50,000 were false positives, causing self-intersection errors and manually corrected. H. Manually edited the only four townships having more than one polygon making up it's shape. I. Spatially verified topology by comparing shapes of sections dissolved to the township to shapes of the township. SELECT * FROM township WHERE NOT ST_Equals(shape, (select SE_Dissolve(shape) from section where section.twp_tin_no = township.twp_tin_no) ) Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 20061101 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: As needed Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -179.230436 East_Bounding_Coordinate: 179.893985 North_Bounding_Coordinate: 71.468273 South_Bounding_Coordinate: 51.201455 Keywords: Theme: Theme_Keyword_Thesaurus: BLM-THEME Theme_Keyword: Framework Place: Place_Keyword_Thesaurus: BLM-STATE Place_Keyword: Alaska Access_Constraints: Discretionary, contains no sensitive information - generally considered releaseable. Use_Constraints: Accuracy published on or derived from the official BLM township protraction diagrams. Any hardcopies or published datasets using this data shall clearly indicate their source. Any users wishing to modify this data are obligated to report the extent of their modifications. User specifically agrees not to misrepresent modifications to this data, as approved or endorsed by the BLM. Any discrepancies or errors in this data should be reported to BLM. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Dennis Walworth Contact_Organization: Division of Support Services, Branch of IRM, Data Management Section Contact_Position: Data Administrator Contact_Address: Address_Type: mailing and physical address Address: 222 W. 7th Ave. #13 City: Anchorage State_or_Province: AK Postal_Code: 99513 Country: USA Contact_Voice_Telephone: (907) 271-3237 Contact_Facsimile_Telephone: (907) 271-4549 Contact_Electronic_Mail_Address: dwalwort@blm.gov Hours_of_Service: 0800-1630 Data_Set_Credit: BLM Official Protraction Diagrams; International Boundary Commission for Alaska/Canadian Boundary; ADNR for ongoing coordination Native_Data_Set_Environment: Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.1.0.780 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Attributes assigned to the spatially-enabled township table are defined in the BLM-Alaska State data dictionary for townships. Attributes for townships are defined from the BLM official protraction diagrams. Logical_Consistency_Report: Spatially verified topology by comparing shapes of sections dissolved to the township to shape of the township. SELECT * FROM township WHERE NOT ST_Equals(shape, (select SE_Dissolve(shape) from section where section.twp_tin_no = township.twp_tin_no) ) Completeness_Report: There is a one-to-one relationship between each township in the spatial database and on the offical protraction diagrams Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Section geometries were spatially dissolved and compared to township geometries. No differences in shape geometries were found. The accuracy of the coordinates in this data is absolute due to their theoretical nature, however the source data shows values to the nearest fraction of a second of latitude or longitude as follows: 1. Township Corners: 0.001" as shown on or calculated from official protraction diagrams, except Umiat Meridian latitudes where they are 0.01". 2. Section Corners: 0.00001" as calculated to preserve angularity and distance. 3. Points along Alaskan-Canadian Boundaries: 3a. For points between Tongass Passage and Mt. St. Elias (not including Boundary Point 187), 0.01" as shown in U.S. Department of State, International Boundary Commission (IBC) publication "JOINT REPORT UPON THE SURVEY AND DEMARCATION OF THE BOUNDARY BETWEEN CANADA AND THE UNITED STATES FROM TONGASS PASSAGE TO MOUNT ST. ELIAS, 1952." 3b. For points between Mt. St. Elias and the Arctic Ocean (including Boundary Point 187), 0.00001" to preserve backwards compatibility with National Geodetic Reference Datum of 1983 using U.S., Department of Commerce, National Geodetic Survey (NGS) computer program NADCON version 2.1. 3c. For intersection points of orthogonal township boundaries with the Alaskan-Canadian boundaries, 0.00001" as calculated to preserve angularity and distance. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: unknown Lineage: Process_Step: Process_Description: See Abstract and Supplemental Information for process steps. Process_Date: 20010214 Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Tom Wohlwend Contact_Organization: Bureau of Land Management, Alaska State Office, Division of Cadastral Survey and Geomatics, Branch of Spatial Records Contact_Position: Geodesist Contact_Address: Address_Type: mailing and physical address Address: 222 W. 7th Ave, #13 City: Anchorage State_or_Province: AK Postal_Code: 99513 Country: USA Contact_Voice_Telephone: (907) 271-4224 Contact_Facsimile_Telephone: (907) 271-4549 Contact_Electronic_Mail_Address: Tom_Wohlwend@ak.blm.gov Hours_of_Service: 0800-1630 Process_Step: Process_Description: Populated Township shape from selection set of protraction points for a given township. Most township shapes were correctly populate without additional intervention. Multipolygon townships and townships along the Canadian International boundary required additional automated and some manual intervention to fully incorporate all township/section offsets. Process_Date: 20061101 Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Dennis Walworth Contact_Organization: Division of Support Services, Branch of IRM, Data Management Section Contact_Position: IT Specialist Contact_Address: Address_Type: mailing and physical address Address: 222 W. 7th Ave. #13 City: Anchorage State_or_Province: AK Postal_Code: 99513 Country: USA Contact_Voice_Telephone: 907-271-3237 Contact_Facsimile_Telephone: 907-271-4549 Contact_Electronic_Mail_Address: Dennis_Walworth@ak.blm.gov Hours_of_Service: 0800-1630 Process_Step: Process_Description: Township and Section Protraction Re-engineering: A. Added Section Table B. Add shapes to township and section tables: 1. Spatially-enable township, section, and pro_pt tables to include shape and objectid fields. a. Township shape field ST_Multipolygon b. Section shape field ST_Multipolgon c. Pro_pt shape field ST_Point d. Objectid set to not null, number (38) C. Add formatted MTR to township and section tables. C. Add land desc label field to township and section tables. D. Altered base protraction tables to: 1. Add fields to record the twp and sec pt labels, relative to the twp/sec being defined. Such as: NW, SW, SE, NE, IP, etc. 2. Add field to pro_pt to distinguish protraction points from construction points. 3. Associated the construction points to the appropriate twp/secs based on data in source data file. E. Updated the township features from ST_Multipolygon shapes consisting of only points at the township corners to ST_Multipolygon shapes also containing points of intersect where section lines meet the township boundary. 1. Densified the township shape features with section corners that fall along the twp lines. F. Determined all possible section corners for each township using explicit database relationships. G. Ran program that used Informix Spatial DataBlade and Java 2D framework to densify the boundary by determining the distance between each section corner and all township's boundaries; inserted any points within an extremely small tolerance (0.0000001 degrees) into the township ST_Multipolygon feature. About 1/50,000 were false positives, causing self-intersection errors and manually corrected. H. Manually edited the only four townships having more than one polygon making up it's shape. I. Spatially verified topology by comparing shapes of sections dissolved to the township to shapes of the township. SELECT * FROM township WHERE NOT ST_Equals(shape, (select SE_Dissolve(shape) from section where section.twp_tin_no = township.twp_tin_no) ) Process_Date: 20061101 Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Jarad Bond Contact_Organization: Division of Support Services, Branch of IRM, Data Management Section Contact_Position: IT Specialist Contact_Address: Address_Type: mailing and physical address Address: 222 W 7th Ave #13 City: Anchorage State_or_Province: AK Postal_Code: 99513 Country: USA Contact_Voice_Telephone: (907) 271-3255 Contact_Facsimile_Telephone: (907) 271-4549 Contact_Electronic_Mail_Address: Jarad_Bond@ak.blm.gov Process_Step: Process_Description: NADCON (for Alaska) conversion Coordinates converted from NAD27 values to NAD83 values using NADCON for Alaska. Values checked against several online NADCON utilities. Process_Date: 20060614 Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Dennis Walworth Contact_Organization: Bureau of Land Management Contact_Address: Address_Type: mailing and physical address Address: 222 W 7th Ave. #13 City: Anchorage State_or_Province: AK Postal_Code: 99513 Country: USA Contact_Voice_Telephone: (907) 271-3237 Contact_Electronic_Mail_Address: dwalwort@blm.gov Cloud_Cover: 0 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: G-polygon Point_and_Vector_Object_Count: 655483 SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Label point Point_and_Vector_Object_Count: 18658 SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains Point_and_Vector_Object_Count: 18685 SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Point Point_and_Vector_Object_Count: 4 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Latitude_Resolution: 0.000000000001 Longitude_Resolution: 0.000000000001 Geographic_Coordinate_Units: Decimal degrees Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.257222 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: section83 Entity_Type_Definition: PLSS Townships defined by BLM-Alaska Official Protraction Diagrams Entity_Type_Definition_Source: BLM-Alaska Official Protraction Diagrams Attribute: Attribute_Label: FID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: objectid Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: twp_tin_no Attribute_Definition: Township TIN Number is an indexing system in Alaska for townships. Each township in the state has a unique 5 digit index number. Attribute_Definition_Source: Bureau of Land Management Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 1 Range_Domain_Maximum: 21,200 Attribute_Units_of_Measure: 1 Attribute: Attribute_Label: sec_no Attribute_Definition: Section Number identifies a protracted "section" within a given township. Sections are generally numbered from 1-36. Attribute_Definition_Source: Spatial Data Management System, BLM-Alaska Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 1 Range_Domain_Maximum: 36 Attribute_Units_of_Measure: 1 Attribute: Attribute_Label: mtrs Attribute_Definition: This is a "zero filled" format description of a section. MTRS contains a formatted, concatenated grouping of meridian code, township, township direction, township fraction (if fractional), range, range direction, range fraction (if fractional), section number. Attribute_Definition_Source: Spatial Data Management System, BLM-Alaska Attribute_Domain_Values: Unrepresentable_Domain: Varies by township Attribute: Attribute_Label: desc Attribute_Definition: This is a label field for a section constructed by concatenating tier, range, meridian and section number into a narrative description. Attribute_Definition_Source: Spatial Data Management System, BLM-Alaska Attribute_Domain_Values: Unrepresentable_Domain: Varies by township Attribute: Attribute_Label: shape Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: tin_sec_no Attribute_Definition: Unique identifier for a section in Alaska. Consists of a concatenation of township index number and the two digit, zero-filled section number. Note that while the township index number is a five digit integer, it is not zero filled. Attribute_Definition_Source: Spatial Data Management System, BLM-Alaska Attribute_Domain_Values: Unrepresentable_Domain: Varies by township/section Attribute_Domain_Values: Unrepresentable_Domain: Varies by township/section Overview_Description: Entity_and_Attribute_Overview: Statewide protracted township grid based on BLM's official protraction diagrams. Entity_and_Attribute_Detail_Citation: Attributes are abstracted from BLM's official protraction diagrams. Distribution_Information: Distributor: Contact_Information: Contact_Person_Primary: Contact_Person: Tim Varner Contact_Organization: Division of Support Services, Branch of IRM Contact_Position: IT Specialist Contact_Address: Address_Type: mailing and physical address Address: 222 W. 7th Ave #13 City: Anchorage State_or_Province: AK Postal_Code: 99513 Country: USA Contact_Voice_Telephone: (907) 271-5799 Contact_Electronic_Mail_Address: tvarner@blm.gov Hours_of_Service: 0800-1630 Distribution_Liability: No warrany is made by the Bureau of Land Management as to the accuracy, reliability, or completeness of these data for individual use or aggregate use with other data. Metadata_Reference_Information: Metadata_Date: 20080204 Metadata_Review_Date: 20080204 Metadata_Future_Review_Date: 20090204 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Tim Varner Contact_Organization: U.S. Dept. of Interior, Bureau of Land Management, Division of Support Services, Branch of Information Resource Management Contact_Position: Spatial Database Administrator Contact_Address: Address_Type: mailing address Address: 222 W. 7th Ave. #13 City: Anchorage State_or_Province: AK Postal_Code: 99513 Country: USA Contact_Voice_Telephone: 907-271-5799 Contact_Facsimile_Telephone: 907-271-4549 Contact_Electronic_Mail_Address: Tim_Varner@ak.blm.gov Hours_of_Service: 0800-1630 Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: local time Metadata_Extensions: Online_Linkage: http://www.esri.com/metadata/esriprof80.html Profile_Name: ESRI Metadata Profile