The Victorian Greens want to see another 100 high-capacity Metro trains added to the current projections to further ease commuter pain.

The party announced on Monday it wants to see high-capacity signalling rolled out first on the Mernda, Craigieburn and Werribee lines on top of the current installation on the Melbourne Metro Tunnel, to be completed in 2025, with other lines to follow.

"High capacity signalling and new trains will be a game changer for Melbourne's metro system," transport spokesman Sam Hibbins said.

"This is the biggest step we can take to improve the commute of thousands of Victorians within the next few years."

The party predicts its policy would cost $5 billion for the signalling out to 2032, $3.5 billion over 10 years for the new trains and $20 million to plan future level crossing removals.