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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

ArcGIS Extensions:Network Analyst - Data Preparation

Alan Hatakeyama & Colin Childs

UC2009 Technical Workshop

slide2

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

slide3

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

slide4

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

slide5

Know Your Street Data

UC2008 Technical Workshop

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coincident geometries
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

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creating coincident geometry
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

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slide8

Common fields for street data

  • Need fields for good network analysis

UC2008 Technical Workshop

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8

slide9

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

elevation fields overpass underpass scenario
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

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slide11

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

hierarchy
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

hierarchy considerations
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

roadclass attribute
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

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slide15

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

slide16

Demonstration:

Adding fields for routing

to TIGER/Line® street data

UC2009 Technical Workshop

16

turns in the network dataset
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

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17

slide18

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

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slide19

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

slide20

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

slide21
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

slide23

Demonstration:

Create a turn feature class

Use a global turn penalty

Create and edit turn features

UC2009 Technical Workshop

23

slide24

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

slide25

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

slide26

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

slide27

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

slide28

Adding Signposts to the Network Dataset

  • Signpost tables specified in Directions Settings

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slide29

Demonstration:

Signposts

UC2009 Technical Workshop

slide30

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

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slide31

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

slide32

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

slide33

Walking paths

Streets

Railway

Junction

Transfer point

Edges

Demonstration:

A multi-modal network dataset

UC2009 Technical Workshop

slide34

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

slide36

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

slide37

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

slide38

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

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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

slide40

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

slide41

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

slide42

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

slide43

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

slide44

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

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slide45

Questions?

UC2009 Technical Workshop