The Rail, Tram and Bus Union has welcomed Labor's ongoing pledge of 50 million dollars for the Maldon-Dombarton rail link.
Opposition infrastructure spokesman Anthony Albanese confirmed Labor's commitment to the project should they win next months federal election.
RTBU National Secretary Bob Nanva said construction of the Maldon-Dombarton freight link is essential for jobs and the economy in the Illawarra and South Coast.
The project has been on the drawing board since the 1970's.
"The Maldon-Dombarton link is the Australian transport industry's version of the Loch Ness Monster.
"Everyone talks about it, but no-one has ever seen it.
"This project is crucial for providing a dedicated freight corridor into Port Kembla, therefore removing the need for freight and passenger services to compete for limited space on the Illawarra line," Nanva said.
Labor has indicated it would increase funding if the private sector invested in the project.