Pavement attribution
Background
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.
Attribution on presence and coverage of pavements
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.
Attribution on pavement width
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)
Technical detail
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.
Examples of uses this data does support
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.
Examples of uses this data doesn't support
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.
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