These pages describe the single feature type (OS Open USRN) available for the OS Open USRN product. The attributes associated with the feature type are listed on the following page. The following information is given for each attribute.
The name of the attribute and what it is describing.
The nature of the attribute (for example, a numeric value).
The maximum length of the values in the attribute.
Describes how many times this element is expected to be populated in the data. An attribute may be optional or mandatory within the OS Open USRN product and this is denoted by:
'1’ – Mandatory: There must be a value.
‘0..1’ – Optional: If populated, a maximum of one attribute will be returned.
This technical specification provides detailed technical information about OS Open USRN. It is targeted at technical users and software developers.
OS Open USRN is an open dataset of all Unique Street Reference Numbers (USRNs) within OS MasterMap Highways Network, with an associated simplified line geometry representing the geographic extent of each USRN.
A USRN is a unique and persistent identifier for a street contained in either the National or Scottish Street Gazetteer. Every street, road, track, path, cycle track or way is assigned a USRN by a Roads Authority, Local Highway Authority or Highways England.
This product has been designed to enable users to easily share information held against a USRN with a location and to link together information associated with USRNs, enabling location-specific visualisation and analysis.
OS Open USRN is a vector dataset with a single line feature for each USRN. Each of these features will have accompanying attribution and a simplified line geometry.
The following pages will detail the attribution held against the features in this dataset and provide further information about the source and simplification of the geometry.
This technical specification includes the following sections:
The OS Open USRN Overview details what coordinate reference system is used by OS Open USRN and gives product supply information (including the available format, supply mechanism, coverage and currency).
A JSON (JavaScript Object Notation) file containing version information will be supplied with the product, including the information given in the table below:
| Attribute Name | Source | Data Type | Additional Information |
|---|
A USRN is assigned to the complete street feature and is made up on junction-to-junction segments. It is mandatory for all USRNs to be assigned a Street Type. All streets must have a Type 1 or a Type 2 USRN assigned, but a Type 3 or Type 4 USRN can also represent the same sections of carriageway that the Type 1 or 2 are assigned to.
The following table provides the definitions for different Street Types:
The following table provides the definitions for Street Type values:
| Value | Definition | Type | Example |
|---|
| Value | Definition |
|---|
filename | osopenusrn_YYYYMM | Text | Filename with the publication date of OS Open USRN |
productPublicationDate | date of OpenUSRNs product publication | Date | Format YYYY-MM |
sourceProduct1.productName | "OS MasterMap Highways Network" | Text | Constant |
sourceProduct1.productPublicationDate | publication date of Highways release | Date | Format YYYY-MM |
Designated Street Name | Official Street Name approved by the relevant authority. | Type 1 | High Street, Main Street |
Officially Described Street | Description of a street where an official street name has not been provided. | Type 2 | Road from Littleton to Fred Farm |
Numbered Street | A route or road number allocated by a highway or roads authority. | Type 3 | A11 |
Unofficial Street Name | Street Name that references a Street or part of a Street that is an unofficial local name not designated by the authority. | Type 4 | Lovers Lane |
Designated Street Name | Officially named street. |
Officially Described Street | Officially described street. |
Numbered Street | Officially numbered street. |
Unofficial Street Name | Unofficial local name for a street. |
Street for addressing purposes only | A street which has been created for addressing purposes of the Local Land and Property Gazetteer (LLPG) in English or Welsh Street Naming Authorities. |
The following sub-sections provide details about the attributes included with the single feature type (OS Open USRN) in the product:
A non-persistent integer which is autogenerated and is required within the OGC GeoPackage format.
Type: Integer
Multiplicity: [1]
Unique Street Reference Number (USRN), a unique and persistent identifier assigned by the Roads or Highway Authority.
Type: Integer
Size: 8
Multiplicity: [1]
The type of Street assigned by the Roads or Highway Authority.
See the Street Type values table for allowable values.
Type: Text
Size: 35
Multiplicity: [1]
The aggregated geometry of either matched OS Road Links or the Elementary Street Units.
For more information, see the Geometry page.
Type: Geometry (MultiLineString)
Multiplicity: [1]
The line geometry provided for each USRN is an aggregation of multiple links to ensure that there is a 1:1 relationship between the USRN and a feature. Each USRN will be represented by a single line feature and each line feature will have a single USRN identifier.
OS Open USRN will include geometry sourced from both Ordnance Survey and Roads or Highways Authorities. Where possible, the geometry of streets captured by a Roads or Highway Authority is spatially matched to the geometry of OS Road Links and Path Links. Where this match is successful, OS geometry is used as the source geometry to represent the extent of the Street. Where spatial matching cannot match the geometry captured by the Roads or Highway Authority to OS geometry, the Roads or Highway Authority geometry is used as the source geometry to represent the extent of the Street. Using a combination of geometry sourced from OS and the Roads or Highway Authorities results in all USRNs being spatially represented in OS Open USRN.
Geometry simplification is the process of reducing the scale and complexity of the data whilst maintaining the important elements and characteristics of the features. The line geometry provided for each Street has been simplified to ensure that it provides the most suitable geometry for the purposes of openly sharing and linking information against the USRN, whilst ensuring the integrity of the USRN representation.
This simplification means that:
The number of vertices representing the curvature of streets has been reduced.
Short cul-de-sacs and slip roads are not supplied.
Complex configurations of the road network are represented by a simplified depiction, such as large roundabouts, complex junctions and traffic islands.
This simplification process will never result in the loss of complete USRNs; all features with a unique USRN will not be removed.
Due to the generalisation of the geometry, we recommend a viewing scale range of 1:15 000 to 1:30 000.
It is to be expected that there will be multiple representations of a piece of road or path. Where Type 3 and Type 4 USRN geometry exists, they will overlap Type 1 or Type 2 geometry. For example, Alan Drayton Way is represented by a Type 1 geometry (Alan Drayton Way) and a Type 3 geometry (B3037).
In England, overlapping USRN geometries may also occur where Highways England have an additional USRN allocated for the same street. This is due to Highways England being the responsible authority for trunk roads in England and they will therefore assign USRNs accordingly, whilst Local Highway Authorities will capture all the streets within their authority area, even if they are not responsible.
Additionally, multiple USRN geometries may exist for the same street where the Local Highway Authority boundaries are defined by the centreline of the street, where the geometry will be represented as overlapping.
Please note, the responsible authority information for USRNs is not provided in this product, but is available in OS MasterMap Highways Network.
