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A transport network can be represented by two object classes, defined as Link and Node, which are inherited. Because of the topological attributes of a network, a connection relationship has to be established between the link and node classes. It defines and nature and extent of the geometric connectivity supporting

Introduced in the early 1990s, the shapefile format is one of the most common GIS vector data formats compatible with the majority of software platforms. It was designed as a compromise based on the most widely used database format of the time by indexing it with a feature file. It

The above table represents the turn penalties for a typical intersection between two streets represented as Node A. From each direction, there are three possibilities; going straight ahead, turning left, or turning right. This intersection consequently has 12 turns, each having a specific attributed penalty. Straight flows (1-3, 3-1, 2-4,

A links table can easily be used to construct a connectivity matrix, a core element for measuring accessibility. It can be achieved by using a simple algorithm:

A network can be represented using two tables, one defining nodes and the other defining links. The three core elements (fields) of a nodes table are unique identifiers and locational attributes in a coordinate system, such as latitude and longitude values. In the above example, coordinates are in decimal degrees,

Routing in a network data model can be simulated if the impedance is available to links and nodes. For links, impedance is often characterized by travel time, while turn penalties are often used to characterize impedance at nodes; how difficult (if possible) it is to turn in one direction, as

Geocoding is possible if a linear referencing system is embedded in a network data model. One of the most common linear referencing systems is the address system, where each link has a corresponding street name and address range. The above address range illustrates even (right side) and odd (left side)

By using attributes encoded in the network data model, such as road type, each segment can be displayed to reflect its importance. For instance, the above cartographic representation of a network data model displays three road classes (highway, main street, and street) differently. Descriptive labels for the most important elements

The above graph represents the basic topology of an urban transport network composed of linked nodes. It has been encoded into a network data model to represent reality as closely as possible, both topologically and geographically. Topologically, each node has been encoded with the connectivity it permits, such as whether

Author: Dr. Jean-Paul Rodrigue Network data models offer a digital representation of transportation networks that can be used for planning, operational and simulation purposes. 1. Nature and Utility Graph theory developed a topological and mathematical representation of the nature and structure of transportation networks. However, graph theory can be expanded