The line is back on the agenda following last week’s release of a report from advocacy group Illawarra First.

The report was carried out by the University of Wollongong SMART Infrastructure Facility.

Tagging it the South West Illawarra Rail Link (SWIRL) it called for the line to be duplicated to two tracks and opening it to passenger trains as well as freight.

In the process, it would provide a direct commuter rail link into western Sydney as well as an alternate rail route to the South Coast line.

It estimated the cost at $1.6 billion, calculated a benefit-cost ratio of 1.56 and suggested it could be worth $2.6 billion to the region and create more than 1100 permanent jobs.

On Monday ABC Illawarra reported that a Transport for NSW report also found merit in the rail line.

The Maldon to Dombarton Final Business Case report, calculated the cost of the line at $1.3 billion, the ABC said.

It stated the line would offer time savings of $900 million in value.

Transport for NSW said the report was three years old and specifically looked at freight movement, excluding passenger trains.

A spokesman said the government’s Future Transport initiative was considering improvements to connectivity in the corridor between Maldon and Dombarton.

A Transport for NSW spokesman said the 2014 study did not call for the line to be built but rather said it wasn't yet required.

“A 2014 business case into the proposed Maldon-Dombarton line states that ‘operational and demand modelling undertaken has shown that the line is not required for current operations’,” the spokesman said.

“The proposed Maldon-Dombarton rail link is one of several options to address future capacity constraints in freight rail access to Port Kembla.”