The infrastructure framework agreement grants Aurizon an exclusivity period until January 2016 to develop a port and rail solution for the WPIOP.

Under the agreement, Aurizon must deliver an acceptable base tariff by the agreed milestone date of October next year and it has mobilised a Perth project team supported by Parsons Brinckerhoff, Calibre and AECOM.

"Aurizon's job now is to deliver a commercially attractive and scalable infrastructure solution for Baosteel, AMCI and POSCO,” Aurizon CEO Lance Hockridge said.

“We know that the creation of world-class rail and port export infrastructure is critical to driving globally competitive exports and economic wealth for the country.”

Infrastructure required for the first stage of the WPIOP comprises a new deepwater port at Anketell Point and a 280km railway with capacity of at least 40 million tonnes per annum, with both to be expandable.

All involved partners will work together to finalise an integrated mine, rail and port schedule based on a set of “revised development assumptions”, which will be announced later this month.

Aquila and AMCI had been contemplating an initial 35Mtpa operation with the mine, port and rail to cost $A7.4 billion.

The infrastructure agreement is the first major milestone for the project since Baosteel and Aurizon acquired 50% owner Aquila Resources for $1.4 billion in July.

Aquila had been in a deadlock with equal partner AMCI (IO) – a joint venture between AMCI and POSCO – which prompted the takeover.

But the parties seem to all be committed to advancing the project.

AMCI president Hans Mende said he was pleased to put past issues behind the company.

"The agreement brings together parties that can genuinely underpin delivery of one of the most exciting resource projects on the globe,” he said.

“We're committed to making this greenfield iron ore project a commercial reality and helping establish a new phase of economic investment in Australia."

POSCO raw materials senior vice-president Kimok Yun said the delivery of the infrastructure was a key component of the project development.

“All four parties are heading in the same direction and we look forward to working together to progress the project,” he said.

The partners are targeting first exports in the 2018 financial year.

Aurizon is planning to divest its 15% stake in Aquila once it delivers the infrastructure.

Shares in Aurizon dropped 0.3% to $4.725.