The nation's infrastructure advisor has found that a plan to duplicate 13 kilometres of railway tracks in Victoria's west is not value for money, as it would not deliver extra train services to Melbourne.

Another crowded peak-hour V/Line train heads for Geelong. Credit:Joe Armao

Infrastructure Australia has given the thumbs down to plans to duplicate a single section of V/Line track from South Geelong to Waurn Ponds, after the project's business case returned a benefit-cost ratio of just 0.6, which predicts a return to taxpayers of 60 cents for every $1 spent.

The Victorian government will fund $146 million — or 20 per cent — and wants the federal government to provide the remaining $550 million.

Infrastructure Australia assesses business cases for major road and rail projects. The body's decisions help determine how the federal government funds these projects.