The port-rail shuttle project has been suspended despite having $58 million of state and federal money committed to it last year, dismaying businesses eager to see the huge transfer of container freight from trucks to trains.

Commercial property developer Salta is poised to invest $3 million on a one-kilometre rail spur to link its Altona freight terminal to the port, plus $30 million on freight facilities on its site, but said it was pointless spending the money while the port-rail shuttle is on ice.

"Salta has an obligation to build that [rail spur] once certain things have happened, but there is no point until trains can be received at the port," the company's managing director Sam Tarascio said.

The port-rail shuttle involves reviving a disused rail line to the Port of Melbourne docks that runs parallel to Footscray Road, and building three short rail spurs to freight terminals in Altona, Somerton and Dandenong South. It would enable trains to shift goods between the port and freight hubs in the suburbs.

Currently, 100 per cent of Melbourne's imports and exports are transported by truck.

The port-rail shuttle could transfer more than half of this - some 3500 truck movements a day - onto freight rail, an analysis by consulting firm GHD has found.

The analysis found those truck movements could be replaced by 56 daily train trips between the port and the three suburban freight hubs. The $58 million rail shuttle would shift 1.4 million containers a year to and from the port, GHD predicts, and reduce heavy vehicle emissions by 23,000 tonnes.

Salta presented its analysis to the current parliamentary inquiry into the proposed lease of the Port of Melbourne. Its submission, which called on the government to make the port-rail shuttle a reality before leasing the port, has been backed by a host of business and community groups.

The Andrews government hopes to reap about $6 billion from the 50-year lease of Melbourne's port and use the proceeds to honour its election commitment to remove 50 level crossings.

Treasurer Tim Pallas told a port privatisation forum last week that the government was committed to boosting freight rail capacity, despite not committing to the port-rail shuttle.

All would-be port owners will be required to submit plans for freight rail expansion in their bids, Mr Pallas said, and the government would use its step-in powers to cut short the 50-year lease term if the successful bidder failed to honour those plans.

"Now that is the most dramatic of actions and it is one that we will not take lightly because there would be a very substantial investment from the leasehold operator, but we are very serious when we say we want integrated freight solutions and we need rail freight to be a part of those integrated solutions," Mr Pallas said.