Integrating Saturn With Gis

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Integrating SATURN with GISOS ITN™ as a common reference for the network21st October 2010 – Erik R Nielsen

SATURN UGM 2010 OS ITN™ as a common reference

Linking ITN and SATURN

• Introduction to OS MasterMap ITNIntroduction to OS MasterMap ITN• Theoretical background• Features• Why use MasterMap ITN for SATURN Modelling?• Advantages / Disadvantages

• Experiences• Building new networks• Retrofitting an existing non-ITN Layer

• Process as it stands today• Software• Processes• Improvements

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Introduction to ITN (1)• OS MasterMap® Integrated Transport Network™(ITN)

Layer

• Accurate, detailed and up-to-date digital map for Great Britain’s road structure.Britain s road structure. • The Roads Network – representing all navigable roads across Great Britain, from

motorways to alleyways. Each road link has a unique identifier TOID® to which feature and statistical data can be attached to aid location management, asset management and analysis.

• Additional data in Road Routing Information (RRI)


Introduction to ITN (2)• Road Routing Information (RRI)

• has comprehensive restriction and advisory route information, which may influence a driver’s choice of route.

• contains• contains• Mini roundabouts • Width restrictions • Weight restrictions • Bridge heights

• Traffic calming • Vehicle restrictions • One-way roads • Vehicular type access and time restrictions

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How it can benefit you (generally)• If you…

• …have the responsibility for planning, scheduling or providing geographic information to your employees customers or the public it is important to use the latest and mostyour employees, customers or the public, it is important to use the latest and most accurate information available. The ITN Layer has a continuous programme of revision capturing real-world change at the same detailed level nationwide. Changes in the data are made available every six weeks.

• …need a common standard of reference to allow different data systems to communicate with each other, the ITN Layer and TOID infrastructure allow you to have that common reference point.

• need to create and maintain the National Street Gazetteer to level 3 the ITN Layer• …need to create and maintain the National Street Gazetteer to level 3, the ITN Layer supports this.

• …have the additional responsibility of planning and scheduling traceable loads. Using the RRI, users can realise significant benefits in increased customer satisfaction and reduced-expenses journey planning


How OS would like you to see it

• ITN with RRI is supplied in GML format

• RRI is available to all local authorities under the OS SLAs

• Issues with different vendor specific translations of ITN gml

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Supply format

• FeatureGML Example• RoadLinks

• These form a part of the Road Network ‘skeleton’ on which the rest of the collectedThese form a part of the Road Network skeleton on which the rest of the collected features are linked)

• This example also has a Grade Separation ‘value’ at one of its’ ends.• <osgb:networkMember><osgb:RoadLink fid='osgb4000000023377812'><osgb:version>1</osgb:version><osgb:versionDate>2004-11-

17</osgb:versionDate><osgb:theme>Road Network</osgb:theme><osgb:changeHistory><osgb:changeDate>2002-11-

12</osgb:changeDate><osgb:reasonForChange>New</osgb:reasonForChange></osgb:changeHistory><osgb:descriptiveGroup>Road

Topology</osgb:descriptiveGroup><osgb:descriptiveTerm>B Road</osgb:descriptiveTerm><osgb:natureOfRoad>Single

Carriageway</osgb:natureOfRoad><osgb:length>32.39</osgb:length><osgb:polyline><gml:LineString

srsName='osgb:BNG'><gml:coordinates>446069.000,161188.000 446042.000,161192.000 446037.000,161193.000

</gml:coordinates></gml:LineString></osgb:polyline><osgb:directedNode orientation='-' gradeSeparation='1'</gml:coordinates></gml:LineString></osgb:polyline><osgb:directedNode orientation gradeSeparation 1

xlink:href='#osgb4000000023142913'/><osgb:directedNode orientation='+'

xlink:href='#osgb4000000023142919'/><osgb:referenceToTopographicArea

xlink:href='#osgb1000000143417333'/><osgb:referenceToTopographicArea

xlink:href='#osgb1000000143417504'/></osgb:RoadLink></osgb:networkMember>RoadNodes(These form the other part of the Road Network

‘skeleton’ on which the rest of the collected features are linked)<osgb:networkMember><osgb:RoadNode

fid='osgb4000000023148089'><osgb:version>1</osgb:version><osgb:versionDate>2004-11-15</osgb:versionDate><osgb:theme>Road

Network</osgb:theme><osgb:changeHistory><osgb:changeDate>2002-10-

30</osgb:changeDate><osgb:reasonForChange>New</osgb:reasonForChange></osgb:changeHistory><osgb:descriptiveGroup>Road

Topology</osgb:descriptiveGroup><osgb:point><gml:Point


How ITN can benefit you(as a modeller)

• More accurate base data• Predefined road classesede ed oad c asses• One-way streets • Banned turns• Speed bumps

• Standard reference network for additional information• Speeds, bus routes, bus lanes, accidents, counts, RSIs, etc. etc.

• Standard reference network for post processing• Air qualityqua y• Noise mapping

• Enhanced presentation of results

• Network that can interact with surroundings• Cross referencing to real geographic data• Buffer analysis

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ITN to SATURN process• Import ITN from GML to SQL server

2-6 hours elapsed

• Preparations of ITN


p• Pruning the ITN network (selecting core area)• Setting up Sectors• Loading Speed data

• Compacting ITN• Refining the automated outcome

• Include• Exclude• Collapsep• Expand• Split• Zone Connector• Attribute Changes

• Exporting

• Short demonstration:• ITN2SATURN

Building the Network (i)• ITN base layer


The ITN network Road Classification and Nature of Road is used as the primary definition for link selection

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Building the Network (ii)• Aggregated SATURN network from the ITN layer


Using the default selection and manually created control files, a SATURN buffer network may be

t d d t d i b thgenerated and exported in both SATURN DAT & ArcGIS formats. The Network Build process also creates the equivalence between the SATURN link (A-B Nodes) and ITN TOIDS.

Building the Network (iii)• Option to manually identify extra links to be retained


Manual Selection of dditi l ITN Li k t badditional ITN Links to be

included to provide the full connectivity for the SATURN network (eg local ‘rat-runs’).

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Building the Network (iv)• Option to exclude specific features


The Dual Carriageway maintenance link is marked for exclusion as it is not required for the SATURN network.

Building the Network (v)• Option to force the collapse for specific junctions


This complex T junction has been manually selected for collapsing to a single pointcollapsing to a single point node (not currently possible to automatically identify these types of junction to be removed).

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Building the Network (vi)• Option to force expansion to retain complex geometry


Manual selection of ITN Links that must NOT be collapsed to provide the appropriate level of detail in the SATURNappropriate level of detail in the SATURN network.The process automatically collapses links that form a Roundabout or Traffic Island so these need to be manually identified to be retained.

Network Review (i)• Ability to bring together the various proposed revisions and

re-running the process


An example showing how the aggregated (collapsed) ITN gg g ( p )network forms the SATURN links and nodes. The tool provides the ability to continually refine, highlighting areas of network where simplification or ‘infilling’ is needed.

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Network Review (ii)• Checking bus routes on the network


Bus Routes add further information about the road class hierarchy and helping identify links to be included in the SATURN network.The SATURN bus routes may also be created from existing ITN datasets.

Network Review (iii)• Cross-checking with inventory data (eg signal locations)


With the SATURN network derived from ITN, updating the

t k i i ti li k d/network using existing link and/or junction inventory datasets is considerably easier.

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Reviewing an existing network• LTS network on ITN base layer


The high accuracy and currency of the ITN dataset enables an effective review of existing SATURN networks.


Practical experiences (i)

• Creating a very large network• Enormous amount of complex junctions, one way roads, bus only links etc.p j y y• First draft of buffer network produced in 2 days.

• Included:• Speed data (linked to the ITN provided by TfL)• Automatic Node numbering by Sector• Splitters for the coding of bus lanes• Stubs for Centroid Connectors• Node Number Correction information

• Outputs: • SATURN .DAT format • SATURN .GIS format• Node / link type definition files• Sample Outputs Sample Outputs

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Practical experiences (ii)• Developing large networks

• Split into smaller areas and tackle one-by-one• Be careful of boundary issues where new network may interface with other, less detailed


models / networks.

• New challenges• Border and version issues • Requirement to freeze sub-areas to enable simulation coding to begin

• Revision• Revision tool developed to enable fine-tuning of the aggregation process

It ti• Iterative process• Network review• Control file adjustments• New ITN SATURN network• Repeat above steps• Network signoff by Sub-area• Various examples follow showing how the network may be developed

Practical experiences (iii)• Network issues

• Dual carriageway connectors• Wrong link type in ITN• Tiny missing links in manual include files


Tiny missing links in manual include files• Complex Junctions• Automatic Node Location not ideal for visualisation• Edits near borders moves and renumbers nodes

• Changes to algorithm after initial cut• Less sensitive to changes in speed limits• Inclusion of invisible link splitters• Inclusion of Centroid link types• Change in aggregated one-way linksChange in aggregated one way links• Change in traffic calming

• Conclusions• A very good and accurate network structure but …

• Don’t underestimate the amount of manual intervention needed• Systematic review of the network build process is crucial

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LTS retro fit for Epsom Test Network• Benefits

• ITN link relation gives integration with other data sources.


g g

• Additional benefits• Using ITN provides the basis for understanding the state of the current network• Option to dump out a SATURN.GIS file for improved P1X visualization

• Process• Initial cut of ITN-SATURN network was generated from ITN in less than four hours.• Matching of nodes from LTS to SATURN (semi automatic in ArcGIS)• Re-export with new Node IDsp• Only required two iterations of the aggregation process achieved an 95% match with the

existing network

• Issues• Uncovered network issues in the original network. • Steep learning curve to understand the effects of control files• Issues with how dual carriageways may be simplified needs further investigation• Readily adaptable for future network improvements?

Documents

Integrating Saturn With Gis