OS NGD Transport
Introduction to the theme
The OS National Geographic Database (NGD) Transport Theme provides a definitive network dataset and topographic depiction of Great Britain’s roads, railways, tracks and paths. It brings Ordnance Survey’s large-scale road and path content, and routing information together with authoritative information from the National Street Gazetteers (NSGs) and the Trunk Road Street Gazetteer (TRSG).
Data structure
The OS NGD Transport Theme is made up of three collections, which in turn are comprised of 35 feature types. The three collections are Routing and Asset Management Information (RAMI), Transport Features, and Transport Network.
Unique identifiers
Depending on the feature, at least one of the following four main unique identifiers is provided with each feature within the OS NGD Transport Theme:
OSID (Ordnance Survey Identifier): The primary identifier and unique key for this theme.
TOID (Topographic Identifier): An additional secondary identifier which can aid further data linking. TOIDs are an optional attribute and therefore will not always be provided with every feature.
USRN (Unique Street Reference Number): A USRN is a unique and persistent identifier for a street contained in the National Street Gazetteer, which is curated by Local Authority custodians in England, Wales, or Scotland.
Unique IDs: Unique IDs for Maintenance, Reinstatement and Special Designation are strings of up to 17 characters which are comprised of a namespace and a local identifier. For Highway Dedication features, this is a string of up to 25 characters.
You will also find a number of additional identifiers in this theme to help you use the data, including local authority identifiers – these are listed as attributes on the individual feature type pages for the theme.
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