Changes to Ordnance Survey global navigation satellite system control networks and geoid models for Great Britain, Ireland and Northern Ireland

The Ordnance Survey of Great Britain (OSGB), Ireland (OSI) and Northern Ireland (OSNI) have been working together to improve the OSGM02 geoid model resulting in OSGM15. OSGB has also updated the horizontal transformation OSTN02 to create OSTN15. The horizontal transformation for Ireland and Northern Ireland is unchanged.

On 26th August 2016 all three organisations switched to using the new systems and updated coordinates for their GNSS control networks (active stations).

Technics have been monitoring the progress of this change and have subsequently made all the necessary steps to enable its work to be fully compatible with an OSGB36(15) coordinate system.

Ordnance Survey global navigation satellite system changesWhat does this mean for our clients?

Firstly, there are differences between the new OSGB36 transformation and the previous model, OSGB36 (02). This change has resulted in a small average shift in coordinates of about 1cm; the vertical shift would be approximately 0.025m across the majority of the country.

Can we continue to use the old OSGB36(02)?

The positions of the reference stations have changed and we’re still going to see a significant difference in the positions we were expecting. For this reason, we have updated our hardware and software to enable us to work in the new coordinate system. All new projects for which consistency with previous work is not essential will be automatically started in new OSGB36(15).

For ongoing projects already started in OSGB36(02) we will continue using this grid. However, it is clear that the β€˜02’ corrections will only be broadcasted for a fairly limited length of time now, so we must get on board with the new, unless there are mitigating reasons to stick with the old coordinate system.

We’re here to help.

We appreciate that you may have some concerns about the introduction and the use of the new OSGB36(15) and the effect it can have on your project.

So, if you require any specific advice on the coordinate system most suitable for your project please do not to hesitate to contact Adam Bogus at our Nottingham office or email us on