Include a SnakeGrid® File in your Coordinate System

SnakeGrid® files (.dat) enable surveyors working on long, linear projects (highways, railways, and pipelines) to have a coordinate system with scale factor distortion of less than a few parts per million for the length and width of the construction corridor. A coordinate system with a SnakeGrid uses projections to perform transformations between local northing/eastings and their corresponding latitude/longitudes. Intervening points are calculated by interpolation.

To use a SnakeGrid file:

  1. Contact the University College London Department of Civil, Environmental and Geomatic Engineering (www.snakegrid.org) and request a SnakeGrid file.
  2. Provide the department with a map of your project, and purchase the DAT file required to convert global coordinates to SnakeGrid coordinates with minimal scale factor and height distortion along the path of the corridor construction project.
  3. When you receive the SnakeGrid file, save it in the C:\ProgramData\Trimble\GeoData folder (default location) to make it available in the Coordinate System Manager.
  4. Open the Coordinate System Manager and select the coordinate system and zone you need.
  5. On the toolbar, click the Add icon.
  6. In the Coordinate System Properties dialog, select Projection.
  7. In the Projection list, select SnakeGrid projection.
  8. In the Grid file list, select the SnakeGrid file you placed in the GeoData folder.
  9. Specify the South azimuth and Positive direction.
  10. Specify other zone, shift grid, and geoid parameters as needed, and click OK. The SnakeGrid transforms your project's coordinate system.

    If you manually export your coordinate system as part of a Data Collector file (.dc) or JobXML (.jxl) file, you will need to ensure that the SnakeGrid DAT file is manually copied to the GeoData folder on the computer or field device using the DC or JXL file.

    If you export your coordinate system as part of a GCS900 Field Data workflow (i.e., creating a job site design) or using the Machine Job Site Design exporter, the DAT file that the exported DC file references is automatically exported to a GeoData folder alongside the design folder.

Related topics

Coordinate System Manager