GST ON TRANSPORT RECEIPT

I am a GST registered mine owner. I pay transport bill to six truck owners for carrying minerals from my mines to the stack yard. Each trip bill is around Rs 1200/- for such trips within one kilometre. The individual truck owners are also registered dealers having business other than transport. They don't issue any consignment for such small trips. Now, wheather GST is applicable in such situations ? If gst is applicable at all, who will pay the gst ?