I get the feeling if BHP was forced to share 10% of their rail...

I get the feeling if BHP was forced to share 10% of their rail capacity it would be in their interests to offer on the pro rata basis you mention phillip_k.

They would be aware that this would keep ACCC and CB happy whilst offering insufficient haulage to cater for the production plans of wannabes like BRM and FRS.

If a result like that occurred neither BRM or FRS would be entirely happy but clearly the companies would be immediately re-rated on the pro rata basis. Rather than risk the splitting the NWIOA (which I believe has been the key factor in BRM, AGO and FRSs success to date, port etc) I believe a possible union between BRM and FRS would start to make commercial sense if it meant the new entity controlled the 24 mta capacity?

All hypothetical at present but the scenarios are endless with this potential development driven by CB.