My understanding of bulk containers for 40 tonne payload I...

My understanding of bulk containers for 40 tonne payload I imagine they would of used 2 of 20 foot containers open top with tarp which would safely do approx 20 tonne payload per container as a 40 foot container would only have approx 30 tonne payload. The reason I say they would of used 20 foot containers would be legal road transport requirement in Australia when it would of been loaded of docks in W.A to destination... So allowing 20 tonne payload and 2.3 tonne tare for container would allow bogie prime mover and tri axle trailer and would just be road legal weight in Aus.. I image the freight would of been a tonnage rate so to work that out you would need to know what port it left from in Brazil to W.A. and contact shipping agent to get approx price.. Hope that helps