Victorian Labor has promised to spend more than half-a-billion dollars to improve train times in Melbourne's north-east, with 4.5 kilometres of track to be duplicated in a key marginal seat.

The $530 million election pledge from Premier Daniel Andrews means that, regardless of who wins the November 24 poll, there will be duplication works on the Hurstbridge line, after the Coalition made a smaller commitment to double parts of the line.

Labor's Vicki Ward holds the key marginal seat of Eltham, where the promised works will take place, by 2.7 per cent.

Under Labor's plan, the train line will be duplicated between Greensborough and north of Montmorency station for 3km, allowing for more services.

The works also affect the marginal seat of Yan Yean, where another 1.5 km of track between Diamond Creek and Wattle Glen will also be doubled.

Mr Andrews said the works would allow trains to run every 6-and-a-half minutes at Greensborough, every 10 minutes at Eltham and every 20 minutes at Hurstbridge.

Daniel Andrews said the upgrades would also "untangle" the train junction at Clifton Hill. ( ABC News )

A historic single-track wooden bridge at Eltham would remain, with the Government saying duplication along that section was not needed to improve services.

"The hard work has been done to ensure that the new track, the upgraded track, can be put in place without having to bulldoze the footy club, without having to bulldoze the childcare centre, and without having to leave the historic trestle bridge to rot," he said.

The Opposition's $307 million proposal would see that section of the line duplicated. It would also double the track between Greensborough and Eltham.

The Liberals candidate for Eltham, Nick McGowan, said Labor's plan was not a true duplication and would create a bottle neck on the line.

"It's a very sad day for Eltham," he said of Labor's plan.

"For commuters, sadly, what this really means is more congestion on our roads, and more delays.

"What the Labor Party is promising to create here is the bottle neck of the future."

Labor's policy builds on the duplication of the track between Heidelberg and Rosanna completed this year, as well as the removal of two level crossings along the line.

Its plan also includes money to "untangle" the junction of the Hurstbridge and Mernda lines at Clifton Hill to further improve train frequency.