Perth leads the country with 14.2 per cent of freight shifted on rail, about 1 per cent more than Sydney and Melbourne and about 9 per cent more than Brisbane.
Mr Nalder said his department aimed to lift that to 30 per cent.
"My office had a conversation with (US-based transportation) company Watco " and they indicated to us if we were to able to achieve 30 per cent we would be best practice, which suggests a minimum of 70 per cent of our freight would need to move by road,� he said.
Mr Nalder backed up his point by referring to a recent trip to Singapore, a country that takes in 4-5 million domestic containers through its port each year.
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READ NOWMr Nalder said Singapore moved 100 per cent of its freight by truck because it was more efficient.
"I�m not saying ultimately that's what we want to do " we have an aspiration to shift as much as 30 per cent by rail and we're continuing to work on that,� he said.
"In the past 12 months we�ve extended the spur at Fremantle, we're creating bypasses on the rail itself so we can get more traffic onto the rail and we will continue to work at that."