Spatial StatisticsUP206A: Introduction to GIS

Central Feature

Directional Distribution

NETWORK ANALYSISUP206A: Introduction to GIS

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

Service Areas

• Complex polygon generation • Allocation across networks

Closest Facility

• Fixed and mobile asset routing• Emergency response

Driving Directions

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

3 step program

1. Prepare you data by calculating cost fields

2. Create the network database

3. Do your analysis