Topology of a Network Data Model
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 the reality as close as possible, both topologically and geographically. Topologically, each node has been encoded with the connectivity it permits, such as if a left turn is possible or not (although this attribute is not displayed here). Further, a direction has been encoded in each link (directional or bi-directional) to represent one-ways. Geographically, each node is located at a coordinate which matches to the actual intersection it represents. In addition, the links between each node have been decomposed into several segments (not implicitly shown) to respect the positional accuracy of the road they represent.