Description
Connect the [item=green-wire] on the [item=substation] to the global network to enable reading of how many 1-4 trains worth of material this station has in it's buffers.
Add inserters, boxes, and a supply belt to the other side of the track (dont forget to wire the boxes together) to not only increase the buffer size, but also double the fill speed.
With Boxes and bulk inserters on both sides, can fill a car in ~ 5 seconds.