A New Approach to Shortest Route Finding in a Railway Network with Two Track Gauges and Gauge Changeovers

Figure 6

A 3D representation of graph capturing the global accessibility of a certain railway network with two gauges. The two planes (layers) represented are (lower) and (upper). The z-axis is, as usual, the vertical axis. Graph is represented in the upper plane, and its edges are drawn in blue. Graph is represented in the lower plane, and its edges are drawn in red. Therefore, the stations with Iberian gauge tracks are in the upper plane () and their names have an “i” subscript or no subscript at all. Meanwhile, all the stations with standard gauge tracks are in the lower plane () and their names have an “s” subscript or no subscript at all. The x and y coordinates of the stations of the forms and (like and ) are identical. The vertical connections (in green) between the two horizontal planes represent the location of the gauge changeovers (that only sometimes exist in stations with tracks of both track gauges).