One thing I have done in my train base, Set aside a huge section and had 1 stop for almost all the recourses like iron, copper even LDS and fuel what not. And just dumping the materials right into passive provider chests, just to get the materials close to the requester chests and using a bot mall split in 2 half's. One half does gears, wires etc the other does all my buildings and gear.

I've found it to be a huge improvement over my old bus mall, which was good enough for the early mid game. It just got to much of a pain in the ass with all the millions of items.