Date post: | 23-Dec-2015 |
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What is Network Analyst
• The ArcGIS Network Analyst extension allows you to build a network dataset and perform analysis on a network dataset
• Used primarily on Transportation Networks
• This extension is composed of a number of parts:
– a wizard to create a network dataset (in ArcCatalog)
– a dockable Network Analyst window (in ArcMap)
– a Network Analyst toolbar (in ArcMap)
– and a number of geoprocessing tools contained within ArcToolbox
The Toolbar
• The Network Analyst toolbar is a combination of menus and buttons for adding and modifying network locations, generating directions, identifying network features, building networks, and performing analysis on network datasets.
The Network Analyst Window
• The Network Analyst Window is designed to help users quickly and easily manage their network analysis layers and the network analysis classes (containing network locations and results). This is a dockable window in ArcMap.
Network Datasets
• Networks used by ArcGIS Network Analyst are stored as network datasets (_ND)
• A network dataset is created from the feature source or sources that participate in the network
• It incorporates an advanced connectivity model that can represent complex scenarios, such as multimodal transportation networks
• It also possesses a rich network attribute model that helps model impedances, restrictions, and hierarchy for the network
• The network dataset is built from simple features (lines and points) and turns
Network Attributes• Cost
– Measure and model impedances (mostly time or distance)
– Can create custom “cost” fields, such as drive time (ex: Drive time = Distance / Speed limit)
• Restrictions– One way streets, no pedestrians, construction
zones
• Hierarchy– Order assigned to network elements
Key Features: Routing
• Multipoint routing • Add points dynamically or• Add points from an existing point layer
3 step program
1. Prepare you data by calculating cost fields
2. Create the network database3. Do your analysis
Step 1 in detail
1. Obtain a street layer and clip it to your project area– Recommended to use Mapshare’s street data
2. Make sure it has a projected coordinate system (ex: UTM NAD 83 Zone 11N)
3. Add a field “METERS” (or appropriate map units for your layer) to calculate length using “calculate geometry”
4. Add and calculate field “MILES”5. Add and calculate field WALK_MINS
– Average pedestrian walking speed is 5km/h– 5000 meters/60 minutes or 83 meters/minute– WALK_MINS = [METERS]/83
6. Add and calculate field DRIVE_MINS– SPEED_MPH / 60 = [miles per minute]– DRIVE_MINS = [MILES] /([SPEED_MPH]/60)
3 step program
1. Prepare you data by calculating cost fields2. Create the network database
3. Do your analysis