• A network is a system of interconnected elements, such as edges (lines) and connecting junctions (points), that represent possible routes from one location to another.
• Through analyzing this connectivity allows us solve certain questions

Examples:

• Information Networks
• Social Networks
• Stream Networks
• Transportation Networks
• ……

• GIS networks consist of interconnected lines (known as edges) and intersections (known as junctions) that represent routes upon which people, goods, etc. can travel.

• The object traversing the network follows the edges, and junctions appear when at least two edges intersect.

• Junctions and edges can have certain attributes affixed to them that increase the cost of traveling in the network, known as impedance.

ArcGIS groups networks into two categories:

• Utility Networks (utility and river networks: One direction at a time) and
• (3D) Network datasets ([3D] transportation networks: Allow travel on edges in both directions).

3D network datasets: Three-dimensional network datasets enable you to model the interior pathways of buildings, mines, caves, and so on.

• Find routes
• Generate turn-by-turn directions
• Find the best location for your business
• Find closest facilities
• Generate service areas
• Create origin-destination matrices

Find the quickest or shortest routes based on time and/or distance. Solve for two stop locations or create a sequence that puts multiple stops in the best order. Build these routes with live or historical traffic.

Q: What is the quickest way to get from point A to point B?

Generate turn-by-turn directions as you travel on a route.

1. Some analyses in spatial statistics provide more accurate results when network distances are used instead of straight-line distances.

1. Researcher benefit from OD Cost-Matrices. Predicting travel behavior.

2. Businesses, public services, and other organizations benefit from the ArcGIS Network Analyst extension because it helps them run their operations more efficiently and improve strategic decision making.

• More complex connectivity scenarios, such as multimodal transportation networks, are also possible.

The route solver can be used to find the best way to get from one location to another or to visit several locations.

• Quickest and Shortest
• Optimized

Solvers input and output:

• Stops (input)—Input locations the route or routes will visit
• Routes (output)—The resulting route, or routes, from the analysis

• The closest facility solver measures the cost of traveling between incidents and facilities and determines which are nearest to one other.
• The closest facility solver displays the best routes between incidents and facilities, reports their travel costs, and returns driving directions.

Solvers input and output:

• Facilities (input)—Input locations that are used as the starting or ending points in closest facility analyses
• Incidents (input)—Input locations that are used as starting or ending points in closest facility analyses
• Routes (output)—The resulting route, or routes, of the analysis

• An origin destination (OD) cost matrix solver finds and measures the least-cost paths along the network from multiple origins to multiple destinations.
• When configuring an OD cost matrix analysis, you can specify the number of destinations to find as well as a maximum distance to search.

Solvers input and output:

• Origins—The input locations that function as starting points in generating the paths to destinations
• Destinations—The input locations that function as ending points in generating the paths from origins
• Lines—Lines representing connections between origins and destinations and the travel time or distance between them

Solvers input and output:

• Facilities (input)—The input facilities around which the output service area polygons are created
• Polygons (output)—The resultant service area polygons, which cover the areas of the network that can be reached within the given time, distance, or other travel-cost cutoff
• Lines (output)—The resultant service areas as linear features that cover the streets, or network edges, that can be reached within the given time, distance, or other travel-cost cutoff

• Location-allocation solver is to locate the facilities in a way that supplies the demand points most efficiently.

Solvers input and output:

• Facilities (input)—Input locations used as the candidate, required, or a competitor facility from which the actual locations will be chosen from in location-allocation analyses
• Demand Points (input)—A location that represents the people or things requiring the goods and services your facilities provide
• Lines (output)—Line features that connect demand points to the facilities to which they are allocated

Example 1: Locate an ERS center

• Time-sensitive: Make it possible for ambulances to reach the most people within a defined time frame.
• Where should three ERS facilities be placed so the greatest number of people in the community can be reached within four minutes?

Example 2: Locate a manufacturing plant

• Lower cost: Budget on transportation.
• Where should the manufacturing plant be located to minimize overall transportation costs?

• Location-allocation problem types
  • Minimize Weighted Impedance (P-Median)
  • Maximize Coverage
  • Maximize Coverage and Minimize Facilities
  • Maximize Attendance
  • Maximize Market Share
  • Target Market Share
  • Maximize Capacitated Coverage

Facilities are chosen such that as much demand weight as possible is allocated to facilities while assuming the demand weight decreases in relation to the distance between the facility and the demand point.

• Fire department: Where to locate fire stations to reach 90 percent of the community within a four-minute response time?
• Disaster response agency: After a storm, where are the best locations to set up triage facilities, with limited patient capacities, to tend to the affected population.
• Public transit bus stops are often chosen with the help of Maximize Attendance.

The goal is to capture as much of the total market share as possible with a given number of facilities, which you specify. The total market share is the sum of all demand weight for valid demand points. It assumes competitor facilities

• Large discount stores typically use Maximize Market Share to locate a finite set of new stores.
• The market share problem types require the most data because, along with knowing your own facilities’ weight, you also need to know that of your competitors’ facilities.

Target Market Share chooses the minimum number of facilities necessary to capture a specific percentage of the total market share in the presence of competitors (similar to maximize market share).

• A retail store wants to see which potential store locations would need to be developed to capture 10 percent of the retail market in the area.

Network Analyst tutorials

What is the ArcGIS Network Analyst extension?

Location-allocation analysis layer