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ArcGIS Extensions: Network Analyst - Data Preparation

ArcGIS Extensions: Network Analyst - Data Preparation. Alan Hatakeyama & Colin Childs. Agenda. Preparing street data for use in network dataset Oneway streets Hierarchy RoadClass attribute Working with turns Using signpost data Creating a multi-modal network dataset

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ArcGIS Extensions: Network Analyst - Data Preparation

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  1. ArcGIS Extensions:Network Analyst - Data Preparation Alan Hatakeyama & Colin Childs UC2009 Technical Workshop

  2. Agenda • Preparing street data for use in network dataset • Oneway streets • Hierarchy • RoadClass attribute • Working with turns • Using signpost data • Creating a multi-modal network dataset • Evaluators tips and tricks • Parameterized Attributes • Support & Resources • Questions UC2009 Technical Workshop

  3. Street Information Layer information Documentation Format Geometry Attributes Know Your Street Data • What information can be used as a setting in the network dataset? UC2009 Technical Workshop

  4. Directions Primary str names Alternate str names Highway shields Boundary field Signpost data Attributes Cost Descriptor Restriction Hierarchy Review – what is in a Network Dataset? Sources Line features Point features Turn features Connectivity End Point / Any Vertex Z-Elevation fields Connectivity groups UC2009 Technical Workshop

  5. Know Your Street Data UC2008 Technical Workshop 5

  6. Coincident Geometries Case 1 Good quality Poor quality Case 2 • To enable network connectivity to be modeled • Points of coincidence should exist where line features cross or intersect Good quality Poor quality UC2008 Technical Workshop 6

  7. Creating coincident geometry • Include sources in a Topology • Use the Geoprocessing Integrate Tool • Both methods compare features and makes vertices within the cluster tolerance coincident • Inserts vertices where features intersect • Snaps features that are not coincident UC2008 Technical Workshop 7

  8. Common fields for street data • Need fields for good network analysis UC2008 Technical Workshop 8 8

  9. State St 0 0 FROM TO endpoint endpoint Endpoint Line feature Connectivity using Elevation fields • Attribute that enables network dataset to represent multiple “levels” for line features • Applied to line features with coincident endpoints • Planar and non-planar features are supported • Commonly called z-elevation or z-levels UC2009 Technical Workshop

  10. Elevation fields - Overpass/underpass scenario 0 0 1 0 1 0 0 0 Junction Endpoint 0-1 lines do not intersect 0-0 lines at the same junction • Four lines with coincident endpoints UC2008 Technical Workshop 10

  11. F_endpoint T_endpoint FT = traffic only allowed in this direction T_endpoint F_endpoint TF = traffic only allowed in this direction Oneway field – Most common method • Text field containing values: FT, TF, < >, N • “FT” - one-way in digitized direction • “TF” - one-way against digitized direction • <empty> (two-way street) • “N” - No travel If other field values, change expression UC2008 Technical Workshop 11

  12. Hierarchy Primary Secondary Local • Minimizes impedance while favoring higher order roads • Basic assumption: • Higher order roads are “faster” (time),not necessarily “shorter” (distance) • Hierarchy classifies network edges into three ranks when the network dataset is built • Ranks: lower number = higher order road UC2008 Technical Workshop UC 2008 Tech Session 12 12

  13. Hierarchy Considerations • Highest level hierarchy needs to be connected to each other • Take restrictions into consideration • Composition of highest level hierarchy dictates performance vs. accuracy of route returned • Larger: yields more optimal routes, but is slower • Smaller: yields faster performance, but route may be less optimal • Hierarchy values derived from road classification (e.g., CFCC) • Edges per hierarchy guide: *Affected by size of network UC2008 Technical Workshop 13

  14. RoadClass attribute • Used for formatting the text of driving directions • Has no effect on network analysis • Descriptor attribute, five possible integer values: UC2008 Technical Workshop 14

  15. Sorting & Indexing • Problem: • Slow performance generating route and driving directions • Issue: • Poorly spatially sorted data • Indentifying symptom: • ArcMap redraws everything at once vs. redrawing chunks of features • Solution: • Index & Sort data before creating Network Dataset • ArcObjects code to sort on x-coordinates A UC2008 Technical Workshop 15

  16. Demonstration: Adding fields for routing to TIGER/Line® street data UC2009 Technical Workshop 16

  17. Turns in the Network Dataset • Describe transitions between two or more edges • Used to model cost and/or restrictions in the network • Incorporating turn elements – more realistic network solver results • Two options: • Turn features • Global (default) turns • Or Both UC2008 Technical Workshop UC 2008 Tech Session 17 17

  18. 103 102 101 104 Turn Feature • Polyline geometry • Turn feature references edges by: • Feature class ID • Feature ID • Position • Turn elements built by edge references UC2009 Technical Workshop 18

  19. Editing Turn Features • Create and edit turn features in the ArcMap Editor • Edit as you would any other line feature • Snap geometry to each street in turn • Network dataset must be built before editing turn features UC2009 Technical Workshop

  20. Turn feature Global left turn Global Turns • Useful for example – adding a penalty for all left turns • Consist of: • All the implied two-edge turning sequences in the network • No need to create a turn feature for every two-edge sequence in the network • Specify attribute values for global turns • VB Script evaluator; or • Global Turn Delay evaluator UC2009 Technical Workshop

  21. Pre-Logic VB Script Code: a = Turn.Angle If a > 210 And a < 330 Then turnTime = 0.5 Else turnTime = 0 End If Expression: turnTime Straight 0/360 30 330 Left turn Right turn 270 90 150 210 180 U- turn Sample VB Script Code for Global Turn Penalty UC2009 Technical Workshop

  22. … or use the Global Turn Delay evaluator UC2009 Technical Workshop 22

  23. Demonstration: Create a turn feature class Use a global turn penalty Create and edit turn features UC2009 Technical Workshop 23

  24. Converting Existing Turn Data • ArcView 3.x or ArcInfo Workstation data • Convert streets with Feature Class To Feature Class geoprocessing tool • Convert turn table with Turn Table To Turn Feature Class geoprocessing tool • Commercial data with multi-edge turns • Use the Create Turn Feature Class from Multi-Edge Turn Table script from EDN UC2009 Technical Workshop

  25. Signposts • Text seen on highway signs • Typically includes exit number, street name, and/or destination • Has no effect on network analysis • Enhances text of driving directions: • “At exit 73B, take ramp to US-421 North toward N Wilkesboro” UC2009 Technical Workshop

  26. 73 B Exit number Street name(s) US-421 Destination(s) N Wilkesboro EXIT73 B 12 Feature class ID Feature ID 41 • Position 0.7 Signpost Data – Two tables Signpost feature class Actual text on sign 421 NORTH N Wilkesboro Signpost streets table Streets traversed when following the sign For Vendor data “Import Signposts” .NET SDK Developer sample UC2009 Technical Workshop

  27. Signpost data example “At exit 73B, take ramp to US-421 North toward N Wilkesboro” OID 41 OID 43 OID 101 • Signpost feature: OID 42 • Signpost streets table records: UC2009 Technical Workshop

  28. Adding Signposts to the Network Dataset • Signpost tables specified in Directions Settings UC2009 Technical Workshop 28

  29. Demonstration: Signposts UC2009 Technical Workshop

  30. Transfer Point Metro (connectivity group 2) Streets (connectivity group 1) Connectivity for a Multi-Modal Network Dataset • Connectivity groups “connect” at transfer points • Example: Rail stations • Non-connecting edge sources – separate connectivity groups UC2009 Technical Workshop 30

  31. Rail Station Station Entrance Transfer Edge Multi-Modal – considerations for Road & Rail • Road & Rail example – two common scenarios: • Railroad station not on rail track • Railway station entrance not on road endpoint but middle of road • For Railroad stations not along the road • Create “transfer edges” • For station entrances not at the road ends • Create junction with Override policy at station entrance • Insert vertex on street feature at station entrance UC2009 Technical Workshop

  32. Network Attributes – Multi-Modal Network Dataset • Create a cost attribute for each scenario you are modeling • Automobile • Pedestrian (walk only) • Pedestrian using light rail • etc. • Create restriction attributes to prevent invalid traversals • Example: Restrict driving on the rail lines UC2009 Technical Workshop

  33. Walking paths Streets Railway Junction Transfer point Edges Demonstration: A multi-modal network dataset UC2009 Technical Workshop

  34. Evaluators – review • A function that determines attribute values for network elements in a network dataset • Five different types: • Field – Assign an existing attribute field from a network source • Constant – Assign a constant value • Global Turn Delay – Apply additional cost based on turn angle • Function – Apply function to another attribute at solve time • VB Script – Assign expression to generate values at solve time • Custom evaluators can be developed UC2009 Technical Workshop

  35. What happens when evaluators are called? UC2009 Technical Workshop

  36. Evaluators – Tips and Tricks • Field evaluator • Read in values from a field; and/or • Perform calculations using multiple field values • Example attributes: Length, DriveTime, Oneway • Constant evaluator • Same attribute value across all network elements • Example attribute: TurnRestriction • Custom logic • Initial prototyping with VB Script evaluator • Final implementation using Custom evaluator • Better performance UC2009 Technical Workshop

  37. Parameterized Attributes • Network attribute that accepts a parameter • Used to model a dynamic aspect of an attribute’s value Parameterized attribute (Optional) Other Network Attribute(s) Input Parameter value(s) UC2009 Technical Workshop

  38. Bridge clearance: 12’6” Example – implementing a height limit • Requires both a Descriptor and a Restriction attribute • Descriptor attribute • Specifies height limits for each road • Restriction attribute • Stores vehicle height parameter • Performs the appropriate restriction • May use Function evaluator or VB Script • Function evaluator – faster & easier Restriction evaluates to true or restricted if vehicle height exceeds 12 ft, 6 in UC2009 Technical Workshop

  39. Truck height: 16’ Car height: 6’ Bridge clearance: 12’6” Bridge Bridge Using Height restriction during solve • When using solver: • Set attribute restriction on Analysis Settings tab • Specify actual vehicle height on Attribute Parameters tab • Solver Result: • Street is restricted when the actual Vehicle Height is greater than street’s MaxHeight attribute value UC2009 Technical Workshop

  40. ESRI Support Center • Online portal to technical information • Knowledge Base • Technical articles • White papers • System requirements • Downloads • Patches and service packs • Data models • ArcScripts and samples • User forums • Discussion groups • E-mail lists http://support.esri.com UC2009 Technical Workshop

  41. For more information • Network Analyst Product Page • Links to Demos, Brochures/White Papers, and Success Stories • http://www.esri.com/software/arcgis/extensions/networkanalyst/ • Free webcast - Introduction to Network Analyst • http://campus.esri.com/acb2000/showdetl.cfm?DID=6&Product_ID=837 • Free Podcasts • http://www.esri.com/news/podcasts/instructional_series.html • Training - Working with ArcGIS Network Analyst • http://training.esri.com/gateway/index.cfm?fa=catalog.courseDetail&CourseID=50099071_9.X UC2009 Technical Workshop

  42. Network Analyst Technical Workshops • Network Analyst – An Introduction • Offering I: Tuesday, July 14 3:15PM~4:30PM Room 9 • Offering II: Thursday, July 16 8:30AM~9:45AM Room 9 • Network Analyst – Performing Network Analysis with Geoprocessing • Offering I: Wednesday, July 15 8:30AM~9:45AM Room 9 • Offering II: Thursday, July 16 10:15AM~11:30AM Room 9 • Network Analyst – Data Preparation • Offering I: Wednesday, July 15 10:15AM~11:30AM Room 9 • Offering II: Thursday, July 16 1:30PM~2:45PM Room 9 UC2009 Technical Workshop 42

  43. Network Analyst Demo Theater Presentations • Network Analyst Tips and Tricks • Tuesday, July 14 10:00AM~11:00AM Spatial Analysis Island • Using the Network Analyst Vehicle Routing Problem Solver • Tuesday, July 14 12:00PM~1:00PM Spatial Analysis Island • Using Turns with Network Analyst • Wednesday, July 15 1:00PM~2:00PM Spatial Analysis Island • Using Parameterized Attributes with Network Analyst • Wednesday, July 15 3:00PM~4:00PM Spatial Analysis Island • Network Analyst Server: Routing for Web Applications Using ArcGIS JavaScript and Flex APIs • Thursday, July 16 9:00AM~10:00AM Server GIS Island UC2009 Technical Workshop

  44. ArcLogistics Sessions • Technical Workshops • ArcLogistics for Government Fleet Operations: Efficiency, Productivity and Green Friendly • Tuesday, July 14 1:30PM~2:45PM Room 27A • Fleet Management using ArcLogistics and ArcLogistics Navigator • Tuesday, July 14 3:15PM~4:30PM Room 27A • ArcLogistics 9.4 Plans • Thursday, July 16 8:30AM~9:45AM Room 27B • Demo Theater Presentation • Introducing ArcLogistics Navigator • Tuesday, July 14 4:00PM~5:00PM Mobile GIS Island • Wednesday, July 15 11:00AM~12:00PM Mobile GIS Island • Thursday, July 16 12:00PM~1:00PM Mobile GIS Island UC2009 Technical Workshop 44

  45. Questions? UC2009 Technical Workshop

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