Search for triangulation stations

This data, which is no longer maintained, is available for use under Open Government Licence Terms.

The archive coordinates supplied for these triangulation stations have not been realised via ETRS89 and OSTN15. They are the original archive coordinates and can therefore no longer be considered as true OSGB36 National Grid Coordinates of the station. It is expected that agreement between ETRS89/OSTN15 derived coordinates and the original archive coordinates of triangulation stations (down to third order) will be at the 0.10 metre root mean square (r.m.s) level.

All paper records for triangulation stations (each station had a dedicated "file") are now held at The National Archives. The catalogue reference for the files is "OS 69".

The Retriangulation of Great Britain (1935-1962) was responsible for the development of triangulation stations especially the familiar trig pillar.
Read the definitive history of the retriangulation "The History of the Retriangulation of Great Britain 1935-1962" (PDF) Please note: The download is a large (160MB+) PDF format document.
Read the accompanying retriangulation diagrams (Zipped archive) (70MB)

This shows the expected accuracy of stations in relation to others of the same type with the circular area of a given diameter.

The expected accuracy (1 sigma) of one type of control station in relation to another of a different type is shown in the table below. In these cases the expected accuracy applies within the smallest diameter of circular area (from table above) pertaining to the stations used.

For example, the expected accuracy between a secondary trig station and a minor control station is 0.09m. This is with a circular area of diameter of 3km, which is the lesser of 15km for secondary trig and 3km for minor control (from the first table).