Ordnance Survey – Great Britain's national mapping agency
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What is the Integrated Transport Network Layer of OS MasterMap?
The OS MasterMap Integrated Transport Network (ITN) Layer is an accurate, detailed and up to date digital road network for Great Britain. It provides a flexible foundation for publishing, tracking, routing, telematic and asset management solutions and can be fully integrated with all OS MasterMap layers, for example, within Address Layer for to the door routing.
What data is available now?
The road network for GB with Road Routing Information.
What level of detail does the ITN layer offer?
The Roads Network theme includes all public roads and the majority of private roads.
The spatial precision matches that of the OS MasterMap Topography Layer.
A single network supports both asset management and dynamic routing.
Road restriction information includes mandatory turns, one-way streets, vehicular restrictions and bridge heights, weights and widths.
How is the road network described?
Individual sections of road are represented by road link features, which show the general alignment of the carriageway. Road Link 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 many features are in the data?
Roads Network: 7 505 800 features, 566 441 road links and 3 473 878
road nodes;
Road Routing Information features:905 370 features;
DfT numbered roads: 5 842; and named roads: 751 537
Total length of GB roads: 5 426 494.83km
[Statistics as of January 2008]
Other statistics
Most popular road name: High Street - 2 453 occurrences (Church Street, Church Lane and Station Road all occur more than 1 500 times).
Longest single road link: 20.3 km (alongside Loch Arkaig, Scotland).
How much space does the ITN layer require?
450 Mb unzipped
3.9 Gb fully indexed in Oracle® (ITN Road Network and RRI)
How is information about routing represented?
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 restrictions, permissions and other 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
Are settlement names in the data?
Settlement names are no longer included in the data. The 1:50 000 Scale Gazetteer, with many more names, can be used in conjunction with the ITN layer.
Are symbols available?
The data has not been given a style or any symbols because the information does not contain any maintained cartographic position or orientation, which is required in order to symbolise it efficiently. There are a number of partners who are providing this information.
How often is the ITN layer Roads Network updated?
ITN layer data is updated by changes to the Ordnance Survey large scale topographic data, information from DfT, Highways Agency, Highway Authorities and our own field surveyors. The aim is to include information in the OS MasterMap Topographic layer within 6 months of change occurring, ITN layer information, taken from the topographic layer, will be updated shortly after its publication in the topographic layer.
What are the new attributes for RRI?
The new attributions are bridge weight and width restrictions. They will be useful for freight and other heavy goods vehicle users as well as emergency services. For further information >>
What applications has the ITN layer Roads Network been developed for?
The OS MasterMap ITN layer is designed to support many different types of applications, including telematics (both business to business and business to consumer), location-based services, asset management and publishing. The ITN layer Roads Network is ideal for sophisticated data analysis functions, such as real-time routing, down to entry-level mapping for visual functions.
Are car parks included in the ITN layer?
Car parks and similar enclosed traffic areas that are accessed by identifiable roads will have their access roads captured and identified by its attribution. Internal routes within car parks will not be captured.
Will there be polygons and networks in the ITN Layer?
The ITN layer is primarily a topological network. There are also simple bounding rectangle polygons to indicate the extent of named and numbered roads.
Is there a road centreline in OS MasterMap Topography Layer?
No, there is no road centreline. You can use the RoadLink features, but please bear in mind that these may not be in the exact centre of the road carriageway. They are indicative of the alignment only.
Why is the road name not attributed to links?
Because a named or numbered road is a definable entity, the OS MasterMap 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 the road name appear in the data?
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.
Ferry link: why does the ferry link feature not have a geometry?
The ferry link is provided to represent a ferry route by indicating that two ferry nodes are connected. It has no explicit geometry of its own because the precise route of a ferry is much more variable than a vehicle. Some software implementations will join the ferry nodes together which may result in a route that appears to pass over land
What is the data format for the OS MasterMap ITN Layer?
The data format 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 ITN layer TOID.
Some highway authorities have used the ITN layer to create a baseline LSG.
A paper is available explaining how to create a level 3 gazetteer using the ITN Layer.
What network features and attribution are available with the ITN layer and RRI?
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, width and weight 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?
OS receives feedback from local authorities, generally via the Department for Transport, indicating if any roads need to be reclassified from public to private or vice versa. Where these do not clash with the OS specification such changes are incorporated.
ITN technical demo http://www.ordnancesurvey.co.uk/oswebsite/products/osmastermap/demos/itn_tech/index.html
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