Introduction

Transportation simulations need to deal with real world scenarios to be useful. In order to achieve this, it makes sense to write them so that they can read arbitrary real world configurations, even when the initial intention of the project is to use artificial data. For the example case of this text, the minimum content of the data base is some information about the road network, and some information about where people live and where people work.

In this section, the information about the road network is considered. The basis for this is a simple coding that is usually used for graphs, with one file/list for nodes (vertices) and one file/list for links (edges, arcs). The traffic network then is built by identifying links with roads, and intersections with nodes. Our intersections will be extremely simplistic.

The node file typically contains:

• a unique ID number for each node, and

• geographical coordinates.

Additional information can be added for each node, but is not needed for this example.

The link file for this example needs the following information:

• a unique ID number for each link,

• the ID number of the node where the link starts,

• the ID number of the node where the link ends,

• length of the link (length is necessary because a curvy road between two nodes will be longer than the Euclidean distance),

Implementation