Melbourne commuters could be slugged with delays of up to 75 minutes after returning to work from the Christmas break.

Buses will replace trains on a handful of lines in January, adding an estimated 45 to 75 minutes to each journey.

Work on regional tracks will also take place throughout the month.

The lines affected include:

• Passengers in the southeast on the Cranbourne and Pakenham lines will have to take replacement buses between Flinders Street and Westall stations from January 2 to 13.
• The entire Gippsland Line will be on buses for the same period.
• Cranbourne, Pakenham and Gippsland commuters are already on replacement buses and have free transport this month at a cost of $1 million, to make up for months of disruption this year. Normal fares will return after December 23.
• Passengers travelling between Flinders Street and Moorabbin on the Frankston line from January 2-13 will also have to catch buses.
• The Bendigo, Swan Hill and Echuca lines between Sunbury and Swan Hill will be on buses from January 12 to 27, for maintenance.
• Buses will replace trams for maintenance between Warrigal and Camberwell roads in Melbourne’s south east from January 3 to 12.
• There will be overnight and weekend works on the Belgrave/ Lilydale, Waverley, Alamein, Sandringham, Sunbury, Werribee and Williamstown lines.

The government said the work was being done over December and January when fewer people were travelling to work.

Cranbourne and Pakenham lines are being upgraded in preparation for new high-capacity metro trains rolling onto the network in the middle of next year.

The trains will be able to carry 20 per cent more people.

The work is also being co-ordinated with the construction of the Metro Tunnel eastern entrance at South Yarra.

The intersection in Plenty at Yan Yean, Diamond Creek and Aqueduct roads will also be closed from January 2 to 24 as part of the $131 million duplication of Yan Yean Road.

Labor flagged the construction works on Tuesday, saying it was part of the state’s “unprecedented pipeline of major transport projects”.

Transport Minister Jacinta Allan encouraged commuters to plan their travel.

For information about disrupted areas, visit the government’s Big Build site.

Visit the PTV or VicRoads websites to plan your journey.