Extensions > Network Analyst > Getting started with Network Analyst
Types of networks |
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Release 9.2
Last modified August 15, 2007 |
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A network is a system of interconnected elements, such as lines connecting points. Examples of networks include highways connecting to cities, streets interconnected to each other at street intersections, and sewer and water lines that connect to houses.
Connectivity is inherently important in order to travel over the network. Network elements, such as edges (lines) and junctions (points), must be interconnected to allow navigation over the network. Additionally, these elements have properties that control navigation on the network.
In GIS, networks are widely used for two kinds of modeling—transportation and utility network modeling.
Transportation network
Transportation networks are undirected networks. This means that although an edge on a network may have a direction assigned to it, the agent (the person or resource being transported) is free to decide the direction, speed, and destination of traversal. For example, a person in a car traveling on a street can choose which street to turn onto, when to stop, and which direction to drive. Restrictions imposed on a network, such as one-way streets or "no U-turn allowed", are guidelines for the agent to follow. This is in stark contrast to the utility network.
In ArcGIS, transportation networks are modeled using network datasets.
Learn more about the network dataset
Utility network
A utility network is directed. This means the agent (for example, water, sewage, or electricity) flows along the network based upon certain rules built into the network. The path that the water will take is predetermined. It can be changed, but not by the agent. The engineer controlling the network can change the rules of the network by opening some valves and closing others to change the direction of the network.
In ArcGIS, utility networks are modeled using geometric networks.
Learn more about the geometric network