You'll find this file within the game directory, in Sid Meier's Railroads!\Assets\XML\_SCENARIOS_\Germany
It's a 601x4808 pixel .tga image. That is, eight 601x601 pixel areas arranged in a vertical column.
The 601x601 pixels represent a 10x10 grid size map, or 100 sq. units, the default map size.
(So, one grid 'unit' = 60x60 pixels. Its possible to create maps up to 225 sq, units, which have a 901x901 pixel representation in the .tga image file.)
Referring to my table below,
Using Paint Shop Pro, I pasted a copy of each of the zoomed-in sections of the .tga 'as new layer' such that the opacity of each can be adjusted with the % sliders. This helps to gain an understanding of how the layers correlate. You can slide up the opacity of each layer in turn to see what features it matches up with in other layers, and what regions of the map it affects.
(If you have PSP, the composite layered file shown below is here.
You'll need to turn on the Layer Palette, its icon looks like this: in the PSP v7 toolbar)