BLM Alaska Protracted Grid Data

Note - these files are from an earlier snapshot of the protracted grid and are not current. An update will be provided at a later date.

BLM- Alaska's Protracted Grid is a data set of protracted coordinates and other attributes, defining the protraction of townships and sections in Alaska. The coordinates precisely delineate the township and section grid as defined on the official BLM protraction diagrams. See the Metadata for more information on this data set.

This page provides the protracted grid in an alpha-numeric form. These are delimited text files extracted straight from SDMS relational tables. A template file is included which can be used to recreate the SDMS protracted grid data base schema in MS Access. Once the database is built, the text files can be loaded into your personal protracted grid data base. A data dictionary and data model describing the data fields and database schema, are also provided.

The data are also available as GIS layers in shapefile or ArcInfo coverage format.

Files

1. Delmited text files (Note all text files use | as a delimiter)
   • pro_poly.zip: Table pro_poly - Protraction Polygon identifies a closed polygon that spatially depicts a protracted township or section. A township or section may have more than one polygon. Each polygon must be identified with one and only one township.
   • pro_polypt.zip: Table pro_polypt - Protracted Polygon Point relates a protracted polygon to a set of points that spatially depict that polygon. A set of polygon points are sequentially ordered in a drawing order, with the first point repeated as last point.
   • pro_pt.zip: Table pro_pt - Protraction Point contains the corner coordinates for protracted polygons.
   • township.zip: Table township - Township is a rectangular tract of land usually six miles square. It is identified by Principal Meridian. a row (tier or township), column (range), and direction from the meridian initial point. Township contains information about the protraction of a Township.
2. Access Database template (protracted_grid.mdb)
   • The access database contains the structure only. To use the protracted data in access you must import the text files into the structure
3. Protraction.rtf - Data dictionary for the protracted grid tables
4. sdms_protraction.png - Data model for the protracted grid tables

• Downloading and extracting the text files requires approximately 318 Mb
• To download, extract, and import text files into Access you will need upwards of 1Gb of free disk space. Once fully populated the Access database will be approximately 566 Mb.

• To uncompress the download files you will need either unzip (Unix) or Winzip (Windows)
• To import the text files into Microsoft Access you will need Microsoft Access 2000 or higher
• The delimited text files should be easily imported into all major RDBMS packages

• unzip: unzip <file name>
• Winzip: Double click on the file in Windows Explorer to open it in Winzip. Click on the Extract button to uncompress the file and save it to disk

It is important to import the files in the following order:

1. township
2. pro_pt
3. pro_poly
4. pro_polypt

1. Open protracted_grid.mdb in Access by clicking on it in the Windows Explorer
• The Access file contains the structure and relationships required to create the protracted grid database
2. On the main menu, select File|Get External Data|Import
3. Navigate to the directory where you saved the uncompressed text files
4. Change the file type to Text Files and select the text file to import:
5. Click Import
6. Change the format to Delimited:
7. Click Next
8. Change the delimiter to | by clicking on Other and typing | in the text box:
9. Click Next
10. Choose to store the data in an existing table. Use the drop-down box to select the existing table that corresponds to the text file you are importing:
11. Click Next
12. Click Finish to do the import: