Commuters travelling into the city from the east, south-east and north-east will be forced to wait up to an hour before hitting the city centre, as the Andrews Government capitalises on the quieter holiday period to carry out a two-week construction blitz.
The works are part of a $30 billion government program to boost road and rail capacity across the network.
Commuters on the Cranbourne/Pakenham and Frankston lines have been warned it will take between 40 to 75 minutes to reach the city, due to level crossing removal works and signalling upgrades.
Buses will replace trains between Moorabbin and Flinders Street on the Frankston Line from January 2-9 and on the Cranbourne/Pakenham line between Flinders Street and Westall from January 2-9, and between Caulfield and Dandenong from January 10-17.
Commuters travelling on the Eastern Freeway to the city are being told to prepare for up to 60-minute delays, as Hoddle Street closes from the Eastern Freeway to Victoria Parade from January 7 to 14, while 20-minute delays will extend from January 15 to mid-2018, between the Eastern Freeway and Vere Street.
This marks the start of the Streamlining Hoddle Street Project - a bid to reduce delays on Punt Road and Hoddle Street by changing the way right turns are made, including creating a dedicated right-turning lane onto Olympic Boulevard for people travelling south on Punt Road.
Speaking to media at Caulfield Station on Tuesday morning, where about half a dozen buses were parked to transport commuters, Acting Roads Minister Philip Dalidakis??? said the Andrews Government was undertaking a significant infrastructure investment.
"At the end of these 14 days, we will already have significantly improved a lot of the road and rectification works that we're doing," he said
"What we are trying to do is build a better road and rail system to make it easier for people to get around, to improve the travelling time for our public.
"There is no gain without pain."
Hurstbridge line commuters are being told it could take an hour to reach the city, as buses replace trains between Clifton Hill and Macleod Stations from January 18-23, as works continue to duplicate track and remove two level crossings.
The M80 will also be shut Greensborough-bound, between the Calder Freeway and Sunshine Avenue on January 12-15, and Altona-bound, between Sunshine Avenue and the Calder Freeway on January 19-22. Commuters are being told to allow an extra 75 minutes travel time.
Lygon Street will be closed to traffic and trams between Elgin and Weston Streets between January 3-16 due to tram track renewal works. The intersection of Lygon Street and Brunswick Road will be closed between January 3-8.
In the city, works on the $11 billion Melbourne Metro Tunnel will see traffic changes and closures hit Flinders Lane between Swanston and Russell Streets and Franklin Street West between Swanston and Sturt Streets from January 10-13 and January 30-9.
Traffic will be detoured via Russell, Collins and Elizabeth Streets.
Works on the new underground rail will also see St Kilda Road traffic disrupted by a series of lane reductions in each direction between Toorak Road West/Kings Way and Dorcas Street. Trams will not be affected.
After these works, the same stretch of St Kilda Road will be reduced to one lane in each direction for up to four years.
Public Transport Victoria chief executive Jeroen??? Weimar??? said work on the south-eastern lines was to boost signalling work along the lines before the arrival of the new high capacity trains at the end of this year.
More than 300 extra buses have been ordered to service these lines and were operating smoothly so far, said Mr Weimar.
"This is the quietest time of year on the transport network, especially the public transport network ??? so we are using this quiet period to do these complicated and invasive works on the Dandenong and Frankston lines.
He said Caulfield Junction was "one of the most important bottlenecks of the entire network".
"There is signalling infrastructure that hasn't been touched for 50 years, and we're using this opportunity to get in, to fundamentally reset some of our signalling, to make it ready not only for our new high-capacity trains ??? but to improve the punctuality and reliability of our existing services."
He said buses would continue to run along the busy Hoddle Street route during the closure.
Buses will also replace trains between Epping and South Morang stations on the South Morang Line between January 12-13, adding an extra 30 minutes travel time.