Network Attributes
Besides the elements of point, line and turn in GIS network, each element has the significant spatially geographical meaning, that is attribute. Each attribute has its own name, usage, unit and type, which is used to describe the property of the element. It could directly or indirectly influence the network flow, such as the weight limit of the vehicle to pass a bridge, the height limit of the vehicle to pass a tunnel.
The attributes from different elements can be classified into four classes, cost, description, restriction and hierarchy(road level).
Item |
Description |
|---|---|
Cost |
The cost includes distance and time, which is used to store how much energy it takes to pass a segment or a centroid, such as the traveling time or the unloading capacity of different depots.
The cost can be a fixed value or a value that changes with states or time. For instance, during the rush hours, the accessibility of the road to transfer resources will change. In addition, the cost can be a single cost or a compound cost. For instance, the strict road accessibility to transfer resources should consider the width, vehicle flow, weather, location, etc. |
Description |
It describes the overall property of the network element, such as material of the road, the features of the lane. |
Restriction |
It limits the accessibility of element to transfer resources, such as one-way road, two-way road, height limit, speed limit, etc |
Hierarchy |
The road levels. It identifies the priority of the roads to be picked to calculate route. Hierarchy can be classified into three major classes:
0: Primary- The road of the highest level, in general, it refers to Freeway or Expressway.
1: Secondary- The road of medium level, it refers to the major roads or the arterial roads.
2: Local- The road of the lowest level, it is equal to the local streets. |
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