The proposal to quadruple the size of the Port Kembla Harbour expansion would only be successful if the Maldon-Dombarton Rail Link was completed, a senior University of Wollongong academic says.
Associate Professor Philip Laird, from the Faculty of Engineering and Information Sciences, said the line was the only real option for moving freight associated with the proposed development.
"It's a positive move but it won't work well unless it has adequate rail infrastructure," Prof Laird said.
The Maldon-Dombarton link, which would connect the northern section of the Southern Highlands to Port Kembla, is already one-third complete. It is one of three possible options suggested to help handle the increased freight associated with the expansion.
The other two include "progressive upgrades to the Moss Vale to Unanderra line" and an introduction of higher-quality trains and braking systems. Bulk train operations were expected to increase from four to 13 trains a day for stage one, the report said.
The NSW Ports Consortium also predicted a 30 per cent increase in road traffic associated with the modification during construction, from 27 trucks an hour to 35.
Prof Laird said that if this meant more trucks on Mount Ousley, it was unlikely the road could handle the increased traffic.
"Mount Ousley isn't a good option for the future growth of Wollongong and the South Coast," he said.
"The Port Kembla expansion to date has already put more pressure on Mount Ousley, Picton and other roads."
However, the NSW Ports Consortium indicated only minor delays on Old Port Road and Five Islands Road.
It said: "The level of construction traffic proposed would not result in any significant traffic impacts on the existing road network.
"There would be potential for some local traffic to experience travel time delays."