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ITN Path Routing Information (PRI)
Go to: Theme definition | Simplification and priority of routing information features | Representation of captured information
In OS MasterMap® Integrated Transport Network™ Layer (ITN), Path Routing Information provides information that may affect a pedestrian's choice of route. This could be either restriction information, such as a prohibited access, or advisory information, such as the presence of a subway or steps.
PRI features reference the underlying Urban Paths Network features PathLink or PathNode to provide their location. The relationship between PRI features and the Path features they provide information for is illustrated in the Urban Paths and PRI relational model.
A definition
Description: Information referencing features on the Urban Path Network theme that may affect a pedestrian’s choice of route. PRI features are captured as one of five types.
Theme rule: theme = ‘Path Routing Information’
Features:
- PathNodeInformation
- PathLinkInformation
- PathRouteInformation
- PathPartialLinkInformation
- PathPartialRouteInformation
Note: Path Routing Information is described as a ‘theme’ within the supplied GML. However because of its current limited extent, it is not available as a separate theme and is included with the path geometry theme (Urban Paths) at this time. As the content for PRI is developed, Ordnance Survey may choose to make this theme available separately, as we do with the Road Routing Information theme.
Simplification and priority of routing information features
PRI features attempt to record the effect and the nature of the real-world restriction or environmental factors. However, this is not always possible as restrictions, in particular, may manifest themselves in many different ways yet have the same effect.
For example, a single restriction may consist of a one-way path that has a no entry sign, no right or left turn signs and possibly mandatory turn signs on the surrounding paths. This would be represented in the simplest way by recording a one-way street. To ensure a level of consistency, a hierarchy is used when more than one restriction with the same effect occurs at a given location. Only the restriction with the highest priority will be captured.
Priority Restriction type
1 One-way
2 No entry/Access prohibited to/Access limited to
3 Mandatory turns
4 No turn
PRI features primarily model the effect of any restriction in the simplest possible way; secondary to this is recording the real-world manifestation.
Representation of captured information
PRI features are divided into the following five categories.
Information coincident with PathNode features
PRI features that are coincident with intersections of the base network are captured as
PathNodeInformation features.
Information about a PathLink where direction of travel is unimportant
PRI features that apply regardless of the direction of travel to an entire PathLink, or at a point along a PathLink, are captured as PathLinkInformation features. Typical examples of a PRI feature applying to an entire link could be access restrictions such as ‘subways’ or ‘footbridges’.
Examples of a PRI feature at a specific location on a PathLink, regardless of direction of travel, are 'level crossings',' gates' and 'fords'.
Where location along a PathLink is relevant and available, this is supplied as both National Grid coordinates and the distance along the link from its start point.
Information about a PathLink or a number of PathLinks specific to a given direction of travel
PRI features that apply in a specific direction of travel to single or multiple PathLink features are captured as PathRouteInformation features.
Examples would be turn restrictions (which apply to multiple links such as no U-turn), one-way paths (which affect a single link in a specified direction) and access restrictions that apply in one direction only.
Where location along a PathLink is relevant and available, this is supplied as both National Grid coordinates and the distance along the PathLink feature from its start point.
Information about part of a PathLink where direction of travel is unimportant
PRI features that apply regardless of direction of travel to a portion of a single PathLink are captured as PathPartialLinkInformation features.
An example could be an access restriction that applies at a specific time and only applies to a section of a PathLink feature.
The start and finish points along the PathLink feature are supplied as both National Grid coordinates and the distance along the PathLink feature from its start point.
Note: These features will not be introduced in the first release of Urban Paths but will be introduced later in the product lifecycle.
Information about part of a PathLink specific to a given direction of travel
PRI features that apply to a portion of a single PathLink with a specific direction of travel are captured as PathPartialRouteInformation features.
An example would be an access restriction in one direction only, such as a gradient, that applies to a section of a PathLink feature.
The start and finish points along the PathLink feature are supplied as both National Grid coordinates and the distance along the PathLink feature from its start point.
In this section:
ITN Technical specification – home
ITN Road Routing Information (RRI) theme
ITN Path Routing Information (PRI) theme
Feature types and attribution in the Road Network theme
Feature types and attribution in the Road Routing Information theme
Feature types and attribution in the Urban Paths Network theme
Feature types and attribution in the Path Routing Information theme
Descriptions of ITN Layer attributes
Attribution checklists for the Road Network and Urban Paths Network themes
ITN attribute definitions and values
This web page is part of the technical specification for OS MasterMap® Integrated Transport Network™ Layer. For the terms that apply to use of this specification, refer to Purpose of this specification.