Within the OS NGD Transport Theme, in the Transport Network Collection, there is a Road Link feature type which represents a line geometry for Great Britain’s road system.
This feature type provides a routable network, when used in conjunction with the Road Nodes feature type. Specific pavement attribution is provided against a road link (Version 2 schema) as described below.
Total metres of pavement present (includes both sides of the road).
Total coverage of pavement as a percentage (includes both sides of the road), e.g. if there is 50% coverage on the left-hand side, and 50% coverage on the right-hand side without any overlap then a 100% value will be assigned.
Total metres of pavements on the left side of the road.
Percentage coverage of pavement on the left side of the road.
Total metres of pavement on the right side of the road.
Percentage coverage of pavement on the left side of the road.
When allocating a pavement as left- or right-hand side of a road the direction of ‘digitisation’ of the Road Link feature is used, as determined by the startnode and endnode attribution of the road link.
Minimum Width of the pavement along the road link (includes both sides of the road)
Average Width of the pavement along the road link (includes both sides of the road)
To assign pavement information to Road Links we have used an algorithm which uses the pavement polygons which have been captured as part of Ordnance Survey’s topographic data capture and the road link data. Therefore the pavement attribution has not been surveyed as identified in its metadata attributes.
A buffer based on the average width of the Road Link is used to identify if a pavement exists along a Road Link. Generally, a pavement is associated with a road if it is immediately beside the road edge or at a short distance, without a physical barrier. Where the pavement is further away from the road edge or a physical barrier exists, the feature will be captured as a Path, as it will not meet the definition of a pavement.
When allocating a pavement as left- or right-hand side of a road the direction of ‘digitisation’ of the Road Link feature is used, as determined by the startnode and endnode attribution of the road link.
To ensure this feature type remains a fully routable network, some generalisation has taken place when assigning the pavement attribution. For example, to account for small gaps in pavement coverage at road junctions – meaning the pavement presence will still be set at 100% in these scenarios. This does not mean we have generalised or altered the road network data itself, just the way we assign pavement presence attribution.
Routing applications, which could use the specific pavement attribution to build logic to consider where roads are walkable. For example, a routing engine could decide that if there is 90% pavement coverage then this can be used for walking in their models.
High level understanding of whether a pedestrian can walk down a road.
Identify road links where there are significant pinch points in pavements.
Support analysis to identify how many roads in a given area have pavement coverage, and to identify those with lower overall pavement coverage to aid decision making.
Support asset management by allowing analysis into how many metres of pavement exist in an area of interest.
Provide understanding of whether adequate pavements exist to link new housing developments to key hubs in the local area.
Visualisation use cases to depict exactly where a pavement is located.
Understanding exactly where a pavement starts and ends along a road – the Pavement Link feature type will help with this use case.
A Road Track or Path feature type is found within the OS NGD Transport Theme, under the Transport Features Collection.
This feature type provides a polygon representation for transport-related features, which includes pavements. To identify the features which represent pavements you can filter on the Description attribute for a value of Pavement. This will result in you obtaining a polygon representation of the pavements for your areas of interest.
Pavement polygons have been captured as part of Ordnance Survey’s topographic data capture and are ‘surveyed’ features. These features are not segmented per road/street but are contiguous until broken by a real-world feature such as a road.
These features (unlike those described in following sections) do not contain specific attribution on pavement width, total presence, or sides of specific roads and streets.
An accurate depiction of the location and extent of pavements, primarily suited for visualisation use cases.
Allocation of pavement widths for entire pavement polygons (noting these polygons are not clipped to roads).
This polygon dataset has not been designed as and is not a routable network.
The pavements are not split into polygons only for roads they correspond to.
A linked dataset to the road link or pavement link data. There is no relationship between these polygons and the other two related feature types: Road Link and Pavement Link.
The Pavement Link feature type can be found in the OS NGD Transport Theme, in the Transport Network Collection.
This feature type provides a geometry to depict pavement presence which is derived from the Road Link feature type geometry and as a result will be coincident with the Road Link features.
A Pavement Link feature is provided when a pavement is present and an individual feature will be created to represent each side of the road. As a result, when a pavement is present on both sides of a road, two Pavement Link features will be provided with the same geometry, whilst the attribution on the feature will specify which side of the road the given feature is associated with.
The Pavement Link feature represents the start and end points of the section of pavement. If comparing this geometry to the Road Link feature then you would expect to find ‘gaps’ in the Pavement Link features where pavements are not fully connected or do not exist.
All Pavement Link features have a linked identifier to the Road Link feature they are associated with (the roadlinkid attribute).
The Pavement Link feature type aims to give a granular depiction of where a pavement exists along a road link.
To create the Pavement Link feature type we have used an algorithm which uses the pavement polygons which have been captured as part of Ordnance Survey’s topographic data capture and the road link data.
A buffer based on the average width of the Road Link is used to identify if a pavement exists along a Road Link. Generally, a pavement is associated with a road if it is immediately beside the road edge or at a short distance, without a physical barrier. Where the pavement is further away from the road edge or a physical barrier exists, the feature will be captured as a Path, as it will not meet the definition of a pavement.
When allocating a pavement as left- or right-hand side we use the direction of ‘digitisation’ of the associated Road Link feature, (as determined by the startnode and endnode attribution of the road link), with a separate Pavement Link feature being provided for each side of the road, which in some instances can result in overlapping geometries.
Understanding where (extent and side of the road) a pavement exists along any given road link. This provides additional information above and beyond that on the road link for identifying start and end points of a pavement. This is particularly useful when undertaking street works to identify whether a pavement might be impacted in any way by the planned street works.
Identifying more accurately where pinch points exist along a stretch of pavement, using the more detailed pavement link geometry to identify their location.
Pavement Link features are a discontinuous set of geometries and therefore not a routable network. Pavement Link features provide a more accurate representation of start and end points of pavements, which are not contiguous or topologically structured meaning the data is not intended for routing use cases.
A pavement centre line. If you would like a more accurate visual depiction of pavements the data in the Road Track or Path feature type provides a better solution.
Pavement definition - A raised, paved or man-made surface for pedestrian use at the side of a road.
Understanding the location of pavements can help provide insight into the accessibility of an area for pedestrians, as well as giving useful information for maintaining and monitoring these features as assets.
Within the OS NGD there are several feature types which will allow you to view and analyse pavement data, each with their own designs and intended use cases. These pavement representations are all found within the OS NGD Transport Theme and are listed below:
A polygon representation in the Road Track or Path feature type.
Specific pavement attribution provided on the Road Link feature type describing the presence and dimensions of pavements associated with the specific Road Link.
A dedicated Pavement Link feature type to help you understand where individual pavements start and end, and the pavement widths for each side of the road.
The following sections give more detailed information about the above three representations and how they can be used, to allow you to decide which of them is best suited for your use case.
