GPS or GNSS Control Surveys
  
A robust survey drawing is always created from a solid network of survey control stations. This survey control must be stable and well constructed; preferably in a location that will not be moved or lost. The control observations must be taken with care, utilising calibrated instrumentation and computed with regard to redundant observations and inbuilt checks. Survey control is often also located outside of the proposed survey area to enable recreation of the survey grid after development of the site has taken place.

Once computed and checked, we can document our control for future us with witness diagrams.

We work to either a local grid, or link to O.S National grid as required. We understand the intricacies of grid transformations, OSGB36, ETRS89, WGS84, scale factors, grids, datums and the implications of utilising Ordnance Survey digital data.

Our range of GPS equipment and processing software allows us to provide fixed control solutions over large areas and easily tie into previous survey control placed by others.

Worldwide Geodetic Control

We have the expertise to provide national scale survey grids for large scale survey projects and have undertaken a number of projects of this type on the East Coast and West coast main railway lines.

We also have the capability to work worldwide on geodetic networks and perform RTK mapping of large areas.
For long thin surveys (pipelines, highways and railway projects), we can commission a snakegrid which gives an engineering accuracy scale factor of 1 along the centreline of the survey. Perfect for railway and pipeline surveys over tens of kilometers

Glossary:

GPS = Global Positioning System (U.S owned and administeres)
GNSS = Global Navigation Satellite Systems (Generic term for geospatial positioning on a global scale)
RTK = Real time kinematic
OSGB36 = Ordnance Survey Natoinal Grid reference system
ETRS89 = European Terrestrial Reference System
WGS84 = World Geodetic System (used by GPS / GNSS)

Recent Project examples:

Irish Rail: Dublin to Cork – 165m GPS control survey, with the same distance double levelled for height control.

Please call Nick Blenkarn or Mark Combes on 0844 880 8247 or e-mail webenquiry@severnpartnership.co.uk to discuss your project requirements.