GEOG 379 Lecture Notes - Arcgis, Arcmap, Digital Elevation Model
30 Apr 2018
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GEOG 379 Lecture Notes
Week 12
4/2 – Network Analysis
Network Analysis
• Udestadig eaess / a oad o othe etok i id
What is a Network?
• Set of connected lines
• Can be used to represent flow of traffic, water, or any other entity
• GIS networks are widely used for two kinds of modeling –
o Transportation network
o Utility network
Transportation Network
• Few constraints on travel, flow can be in both directions
• Enter network at most any point
• Exit network at most any point
• Get anywhere from anywhere
Utility Network
• Highly directional
• Entry to network is specified
• Exit points are established
• Cat get to etai plaes
Modeling/ Solving Networks
• ArcGIS can model both transportation + utility network
• Transportation network is modeled using network dataset
• Utility network is modeled using geometric dataset
Network Analyst in ArcGIS
• ArcMap extension that allows for analysis of distance + cost over a network
• Primarily for transportation networks
• Eale Netok Aalst etesio efoe usig it
Network Datasets
• Why necessary
o Stores connectivity, turns, restrictions, etc. associated w/ traversing a network
o Noal featues aet aae of oe aothe
• Network elements
o Edges – connect to other elements (at junctions) + are links over which agents travel
o Junctions – connect edges + facilitate navigation from one edge to another
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GEOG 379 Lecture Notes
• Features
o Shapefile network dataset
▪ Only supports one source of edges/ line
▪ Put all features that will participate in network in same folder
o Geodatabase network dataset
▪ Supports multiple edge/ junction sources – makes multimodal analysis possible
▪ Put all features classes in one feature dataset
Create Network Dataset
• In Catalog, right-click the source of edge features (for shapefile dataset) or feature dataset (for
geodatabase dataset)
• Wizard takes you through
o Naming dataset
o Identifying source feature(s)
o Setting up connectivity, elevation, and turns
o Defining attributes for distance/time
o Set up capability for turn-by-turn directions
Network Analysis Layers
• Store inputs, properties, + results of network analysis
• Select analysis type from the Network Analyst Toolbar
Network Analysis Objects
• Objects required for network analysis
• Key objects
o Stops – on routes
o Facilities – start/end point of closet facility analysis; site in location/ allocation problem
o Barriers – block travel on network
o Incidents – start or end point of closest facility analysis
o Demand points – locations weighted by demand for some service/ product
▪ Ex – zip code centroids
Types of Network Operations
• Best route analysis
• Service area
• Closest facility
• OD-cost matrix
• Vehicle routing problem
• Location-allocation
Route
• Examples of route problems
o Quickest distance from a hospital to police station
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GEOG 379 Lecture Notes
o Shortest distance from school to health center
Service
• Examples
o 5 minute coverage area for fire station
o Areas w/in 10 min driving distance from downtown
o Coverage area for transit stop (w/in defined walking time)
Closest Facility
• Examples
o Find all coffee shops w/in 1 mile (road) distance from your house
o Which 3 hospitals are nearest w/in 10 minute from accident site
o Healthy food options w/in 15 min walking distance of a neighborhood
OD Cost Matrix
• Examples
o Find travel times from all schools to all hospitals
o Find distances from all storage facilities to all supermarkets
Vehicle-Routing Problem
• Examples
o Travelling salesman problem
o Find shortest route connecting all supermarkets from storage facility
o Least cost route connecting all houses where FedEx need to deliver packages
Location-Allocation
• Examples
o Where to build new emergency response stations considering population distribution
and existing stations
o Business location decision considering competitors + customers
Review
• Which is NOT true for Utility Network?
o Can easily model routes from anywhere to anywhere
o True –
▪ Uses Geometric Network data
▪ Highly directional
▪ Have specific entry/exit points
• Which network analysis type will you use to find areas within 5 minutes distance from a police
station?
o Service Area
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Document Summary
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