My last world used 1-4 train cars on a two way rail network arranged in a grid, with train station limits and circuits controlling the station to only be on when it had the right amount of resources. (Whether that be enough resources for an output station or low enough resources in an input station) this was enough to easily handle somewhere near 700 trains traveling between around 800 stations supplying a modular factory that sustained 5.6k spm. I stopped that file due to performance restraints, the train network was capable of much more. On my new space exploration play through I think I’ll stick with the same.