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OS MasterMap Integrated Transport (ITN) Network Layer frequently asked questions
What is the Integrated Transport Network Layer?
The OS MasterMap® Integrated Transport Network (ITN) Layer is the definitive national road network for Great Britain. It provides a flexible foundation for publishing, transport, telematic and asset-management solutions and can be fully integrated with all OS MasterMap layers; for example, within OS MasterMap Address Layer for to-the-door routing.
If a satellite navigation device is routing vechicles wrongly can I make changes to ITN to correct this?
We can check the road designation- A road, minor, private,- and if there are any physical or signed restrictions in place though the actual routing from one destination to another is determined by the software and data providers for SatNav devices. Please see our satellite navigation page for more background and links to report errors to manufacturers.
What level of detail does the ITN Layer offer?
The OS MasterMap® Integrated Transport Network™ (ITN) Layer is the definitive national road network for Great Britain. It provides a flexible foundation for publishing, transport, telematic and asset-management solutions and can be fully integrated with all OS MasterMap layers; for example, within OS MasterMap Address Layer for to-the-door routing.
How is the road network described in the ITN Layer?
In OS MasterMap Integrated Transport Network (ITN) Layer individual sections of road are represented by RoadLink features, which show the general alignment of the carriageway. RoadLink features have attribution to describe the type and nature of the road.
Road type classifications include motorway, A road, B road, minor road, local street, private road – publicly accessible, private road – restricted access, alley and pedestrianised street. The nature of the road classifications includes single carriageway, dual carriageway, slip road, roundabout and traffic island.
The connectivity is described by relationships at the ends of the RoadLink features and a relative third dimension is included to allow for roads crossing at different levels.
Named and numbered roads are represented by compound features referencing the RoadLink features that represent the extent of the road.
How is information about routing represented in the ITN Layer?
In OS MasterMap Integrated Transport Network (ITN) Layer information that may affect a driver's choice of route is represented by additional features that reference the base network. This is known as Road Routing Information (RRI). These features describe physical restrictions, permissions and other signed information relevant to drivers.
The restriction information is not applied to the base network, but is referenced. This allows the range of information collected to be extended in the future and minimises the impact on customers not concerned with routing information.
The main categories of restriction information captured are as follows:
One way
No entry
Access prohibitions
Access limitations
Turn restrictions
Mandatory turns
To whom the restrictions apply and any time constraints are also captured
In the ITN Layer, why is the road name not attributed to links?
Because a named or numbered road is a definable entity, the OS MasterMap Integrated Transport Network (ITN) Layer considers it to be a discrete feature. The ITN Layer adopts a relational structure for the data; road link features describe each section in the road network and the road feature represents the named or numbered road. Every road feature will reference the TOID of one or more road link features that represent the alignment of the road.
How many times does a road name appear in the ITN Layer data?
In OS MasterMap Integrated Transport Network (ITN) Layer, a road feature will occur once for each named road within a specific area in the road feature and is linked to the road link features that make up that road by reference to the constituent road link TOIDs. Numbered roads are created as single features, no matter how fragmented they are; for example, there are 1 017 occurrences of Green Lanes but only one B3181.
What is the data format for OS MasterMap ITN Layer?
The data format for OS MasterMap Integrated Transport Network (ITN) Layer is GML v2.1.2.
Will there be links from the ITN Layer to the Local Street Gazetteer (LSG)?
The structure of OS MasterMap allows for data association; therefore, other datasets, such as LSG data, can be linked to the Integrated Transport Network (ITN) Layer TOID. Some highway authorities have used the ITN Layer to create a baseline LSG.
What network features and attribution are available with the ITN Layer and RRI?
The network features and attribution available with OS MasterMap Integrated Transport Network (ITN) Layer and Road Routing Information (RRI) are as follows:
Road link classifications - Motorway, A road, B road, minor road, local street, alley, pedestrianised street, private road – publicly accessible, private road – restricted access.
Road link types - Dual carriageway, single carriageway, slip road, roundabout, traffic island, traffic island at junction, enclosed traffic area.
Ferry network - Ferry terminals, ferry link and ferry node.
Routing information - No turn, mandatory turn, no entry, access prohibited to (specified vehicle types), access limited to (specified vehicle types), height restrictions, fords, mini roundabouts, traffic calming, gate, tolls, bridge over road, firing range, through route, severe turn.
What is the definition of public and private roads in the ITN Layer?
The definition of public and private roads on Ordnance Survey products has traditionally been based upon an assessment of the accessibility and nature of the road by the data collector. Normally no formal enquiries surrounding ownership and/or responsibility for maintenance were made.
In recent years Ordnance Survey has received feedback from local authorities, via the Department for Transport (DfT), indicating if any roads need to be reclassified from public to private or vice versa. Where these do not clash with Ordnance Survey specification such changes are incorporated into Ordnance Survey vector roads products, such as OS MasterMap Integrated Transport Network Layer (ITN).