Using Graph Layout to Visualize Train Interconnection Data

We consider the problem of visualizing interconnections in railway systems. Given time tables from systems with thousands of trains, we are to visualize basic properties of the connection structure represented in a so-called train graph. It contains a vertex for each station met by any train, and one edge between every pair of vertices connected by some train running from one station to the other without halting in between.

Positions of vertices in a train graph visualization are given by the geographical location of the corresponding station. If all edges are represented by straight-lines, the result is visual clutter with many overlaps and small angles between pairs of lines. We therefore present a non-uniform approach using different representations for edges of distinct meaning in the exploration of the data. Some edges are represented by curved lines, such that the layout problem consists of placing control points for these curves. We transform it into a graph layout problem and exploit the generality of the random field layout model formulation for its solution.