Known Data Issues

This page lists known data issues in relation to the OS National Geographic Database (NGD) themes, collections and feature types. The OS NGD is in its infancy and, as such, will be largely developed and iterated upon in its early life.

As and when we resolve a known data issue, we will remove it from this page.

Generic OS NGD known data issues

Data issue name	Data issue description
Very small number of features not being given the correct 'End of Life' change type	There are 319 features (out of 600+ million) which reside within the 'features' collections (i.e. any OS NGD collection which has a name of 'XXX Features', for example, Transport Features) that have not been given the correct 'End of Life' change type. This means that these features still reside within the supply but should be deleted.

Data issue name

Data issue description

Very small number of features not being given the correct 'End of Life' change type

There are 319 features (out of 600+ million) which reside within the 'features' collections (i.e. any OS NGD collection which has a name of 'XXX Features', for example, Transport Features) that have not been given the correct 'End of Life' change type. This means that these features still reside within the supply but should be deleted.

OS NGD Address Theme known data issues

Data issue name	Data issue description
Isle of Man addresses	A total of 32 address records are currently present in the OS NGD GB Address Collection which should not be contained within this collection as they are actually Isle of Man records. These records are correctly present in the OS NGD Islands Address Collection.
Incorrect change type for addresses moving between feature types	In a very small number of cases, when an address moves between feature types, such as moving from Pre-Build Address to Built Address, the change type given is incorrect. The address 'leaving' the Pre-Build Address Feature Type is correctly marked 'Moved To', but when it enters the Built Address Feature Type, it is incorrectly marked as 'New' rather than 'Moved From'. Your Change-Only Update (COU) processing will still work correctly, and your data holdings will be complete, but the address will have been incorrectly marked as 'New'.
Parish and Community / Ward GSS Codes	The Parish and Community GSS Codes for every feature type have been correctly assigned but incorrectly described as Ward GSS Codes and vice versa. When using these codes which reside in the Related Entities component if you are wanting a GSS Ward code you will need to use the records currently described as Parish and Community GSS codes and vice versa.

Data issue name

Data issue description

Isle of Man addresses

A total of 32 address records are currently present in the OS NGD GB Address Collection which should not be contained within this collection as they are actually Isle of Man records. These records are correctly present in the OS NGD Islands Address Collection.

Incorrect change type for addresses moving between feature types

In a very small number of cases, when an address moves between feature types, such as moving from Pre-Build Address to Built Address, the change type given is incorrect.

The address 'leaving' the Pre-Build Address Feature Type is correctly marked 'Moved To', but when it enters the Built Address Feature Type, it is incorrectly marked as 'New' rather than 'Moved From'.

Your Change-Only Update (COU) processing will still work correctly, and your data holdings will be complete, but the address will have been incorrectly marked as 'New'.

Parish and Community / Ward GSS Codes

The Parish and Community GSS Codes for every feature type have been correctly assigned but incorrectly described as Ward GSS Codes and vice versa. When using these codes which reside in the Related Entities component if you are wanting a GSS Ward code you will need to use the records currently described as Parish and Community GSS codes and vice versa.

OS NGD Administrative and Statistical Units Theme known data issues

Data issue name	Data issue description
Historic European Region Feature Type	This feature type contains updates made to the boundaries post 01 April 2021 (when the feature type was frozen in the Boundary-Line product). This means that there will be differences between the boundaries accessed via our OS OpenData pages and those accessed via OS NGD.

Data issue name

Data issue description

Historic European Region Feature Type

This feature type contains updates made to the boundaries post 01 April 2021 (when the feature type was frozen in the Boundary-Line product). This means that there will be differences between the boundaries accessed via our OS OpenData pages and those accessed via OS NGD.

OS NGD Structures Theme known data issues

Data issue name	Data issue description
Some underground Structure features are missing from the Habitat Coverage Reference table	3 underground Structure features with an OS Land Cover Tier B attribute of ‘Coniferous Trees’, ‘Non-Coniferous Trees’, ‘Scattered Coniferous Trees’ or ‘Scattered Non-Coniferous Trees’ are missing from the corresponding Habitat Coverage Reference cross-reference table.
Duplicate/overlapping Field Boundary features exist	Approx. 20k Field Boundary features are overlapping and 23 of these have duplicate geometries, resulting in more than one version of the same feature in the dataset. This is currently being investigated.
Field Boundary data quality	At the time of launch (March 2024), areas of Great Britain were still to be quality checked and will be improved as part of OS’ continuous quality review programme when updated imagery is available. Most of the known data quality errors are either in Moorland areas or where imagery was captured earlier in the year and vegetated features are ‘leaf-off’. The downloadable file below contains the status of each 10km2 area relating to the quality of the Field Boundary feature classification.

Data issue name

Data issue description

Some underground Structure features are

missing from the Habitat Coverage

Reference table

3 underground Structure features with an OS Land Cover Tier B attribute of ‘Coniferous Trees’, ‘Non-Coniferous Trees’, ‘Scattered Coniferous Trees’ or ‘Scattered Non-Coniferous Trees’ are missing from the corresponding Habitat Coverage Reference cross-reference table.

Duplicate/overlapping Field Boundary

features exist

Approx. 20k Field Boundary features are overlapping and 23 of these have duplicate geometries, resulting in more than one version of the same feature in the dataset. This is currently being investigated.

Field Boundary data quality

At the time of launch (March 2024), areas of Great Britain were still to be quality checked and will be improved as part of OS’ continuous quality review programme when updated imagery is available. Most of the known data quality errors are either in Moorland areas or where imagery was captured earlier in the year and vegetated features are ‘leaf-off’. The downloadable file below contains the status of each 10km2 area relating to the quality of the Field Boundary feature classification.

24KB

Field_Boundary_Status_April_2024.xlsx

OS NGD Transport Theme known data issues

Data issue name	Data issue description
Welsh speed limit changes	On the 17th September 2023, default 20mph speed limits were introduced across Wales. We are aware that these changes are not yet reflected in the Average and Indicative Speed Feature Type. Speed limit data is supplied by our 3rd party supplier quarterly. The most recent supply occurred before the Welsh speed limit changes took place and therefore will not be reflected in the OS NGD until the next supply. We expect the updated Welsh speed limits to be in NGD in December 2023. This issue was resolved on 13 December 2023. Any data ordered or provided after this date will include updated Welsh speed limit data.
Incorrect speed values	In the Average and Indicative Speed Feature Type, the indicative speed value for individual Road Links can be inferred by Ordnance Survey. We are aware that in certain instances some of these indicative speed values are incorrect. We are working to resolve this issue and have an approximate implementation date of the start of July. This issue impacts just over 2% (174 000) of the total Road Links in the Average and Indicative Speed Feature Type. This issue was resolved on 02 July 2023. Any data ordered or provided after this date will include the fixed data.

Data issue name

Data issue description

Welsh speed limit changes

On the 17th September 2023, default 20mph speed limits were introduced across Wales.

We are aware that these changes are not yet reflected in the Average and Indicative Speed Feature Type. Speed limit data is supplied by our 3rd party supplier quarterly. The most recent supply occurred before the Welsh speed limit changes took place and therefore will not be reflected in the OS NGD until the next supply. We expect the updated Welsh speed limits to be in NGD in December 2023. This issue was resolved on 13 December 2023. Any data ordered or provided after this date will include updated Welsh speed limit data.

Incorrect speed values

In the Average and Indicative Speed Feature Type, the indicative speed value for individual Road Links can be inferred by Ordnance Survey. We are aware that in certain instances some of these indicative speed values are incorrect. We are working to resolve this issue and have an approximate implementation date of the start of July. This issue impacts just over 2% (174 000) of the total Road Links in the Average and Indicative Speed Feature Type. This issue was resolved on 02 July 2023. Any data ordered or provided after this date will include the fixed data.

OS NGD Water Theme known data issues

Data issue name	Data issue description
Invalid geometries in Waterbody Catchment and River Basin District Catchment features	Some catchment polygons appear to have invalid geometries in the form of self-intersections, holes, and gaps. Instances of self-intersection are primarily due to the gridded digital terrain model (DTM) used to generate the catchment data provided by the third-party data from authoritative bodies.
Incorrect representation of a Waterbody Catchment name	The Barlings Eau Upper catchment name is incorrectly displayed. This is as per the third-party data from the authoritative bodies.
Non-unique Waterbody Catchment IDs	Two instances occur where the Waterbody Catchment ID is not unique: GB109056040082 and GB104027063230. This is as per the third-party data from the authoritative bodies.
Certain Waterbody Catchment features do not nest exactly within a River Basin District Catchment.	A total of 14 instances occur where Waterbody Catchments do not nest exactly within their associated River Basin District Catchment. This is as per the third-party data from the authoritative bodies.

Data issue name

Data issue description

Invalid geometries in Waterbody Catchment and River Basin District Catchment features

Some catchment polygons appear to have invalid geometries in the form of self-intersections, holes, and gaps. Instances of self-intersection are primarily due to the gridded digital terrain model (DTM) used to generate the catchment data provided by the third-party data from authoritative bodies.

Incorrect representation of a Waterbody Catchment name

The Barlings Eau Upper catchment name is incorrectly displayed. This is as per the third-party data from the authoritative bodies.

Non-unique Waterbody Catchment IDs

Two instances occur where the Waterbody Catchment ID is not unique: GB109056040082 and GB104027063230. This is as per the third-party data from the authoritative bodies.

Certain Waterbody Catchment features do not nest exactly within a River Basin District Catchment.

A total of 14 instances occur where Waterbody Catchments do not nest exactly within their associated River Basin District Catchment. This is as per the third-party data from the authoritative bodies.

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