Setting Up in the Real World – UK Coordinate Systems

Series Index - Setting Up in the Real World

[Update 2020: These coordinate systems are now available as standard in our current applications, the steps below are only relevant to pre 2020 releases]

UK users creating new data should always use the OSGB-GPS-2002 or, on latest CONNECT edition products, the newer OSGB-GPS-2015 GCS when working with the UK National Grid  to ensure that when converted to ETRS89 or WGS84 based datums, projection coordinates are the most accurate possible. Variations of both are also offered on CONNECT Edition where the non-linear transformation is approximated uing a NTv2 grid shift file. These are OSTN02.BritishNatGrid and OSTN15.BritishNatGrid.

The other British National Grids included in our libraries are used to import older data that was created prior to the introduction of OSGB-GPS-2002 and OSGB-GPS-2015.

Some long running infrastructure projects may have particular specifications that overrides this advice. Where project specifications for geo-referencing exist always use them to be consistent with other project participants!

How to access OSGB-GPS-2002 and OSGB-GPS-2015

When you open the GCS Library in MicroStation or AECOsim Building Designer you may not find either OSGB-GPS-2002 or OSGB-GPS-2015.

To make them available download OSGB-GPS-2002 Grid Shift File and extract OSTN02.txt or OSGB-GPS-2015 Grid Shift File (CONNECT Editions only) and extract OSTN15.txt to the appropriate location:

  • MicroStation V8i: C:\Program Files (x86)\Bentley\MicroStation V8i (SELECTseries)\MicroStation\GeoCoordinateData
  • MicroStation CONNECT Edition: C:\Program Files\Bentley\MicroStation CONNECT Edition\MicroStation\GeoCoordinateData
  • AECOsim Building Designer V8i: C:\Program Files (x86)\Bentley\AECOsimBuildingDesigner V8i Ss6\AECOsimBuildingDesigner\GeoCoordinateData

Note: As updating to AECOsim Building Designer SS6 Update 1 is an install over process if you added this file in SS6 it will still be in place after the upgrade.

This will need to be done for every machine that requires this GCS. The product must also be executed once as Administrator and the Geographic Coordinate System Selection dialog opened once. This will trigger the creation of the binary cache files OSTN02._02 or OSTN15._02.

The coordinate systems will then be listed as shown:


If compatibility with this coordinate system is needed please download the OSGB-GPS-1997 Grid Shift File. It should be installed using the method described above.

Also see

Setting Up in the Real World – GeoReferencing