So this here is a theoretical world map for the Rackbulls and their primary rail routes, they are color coded as follows:

Subterranean:
Pink: Primary routes, recently constructed with the use of large scale machine drilling, busy and bustling transport hubs.
Red: Secondary routes, these existed before the primaries and were constructed with significantly less advanced methods, thus they are rather convoluted and lengthy, but remain busy due to traffic demand.
Grey: Inoperable routes that have either been flooded, re purposed, or are on hold for further construction.
White boxes: Bull stations located underground, used as supply hubs and typically surrounded by cities.

Surface:
Violet: Bull routes that have been built above ground, usually to connect with businesses and suppliers, but often are used as extensive rail yards due to all the extra space.
Blue: Rails that belong to non-Bull owned companies, exclusively for surface travel.
Black boxes: Shipyards and producers/business partners to the Rail network.