There's some "good news" for Melbourne commuters - some of their trains will be running slower despite billions of dollars spent upgrading the lines.
A rejigged timetable will be in force next month with the slower trains, but the state government can't say which services will be affected.
Victoria's Public Transport Minister Melissa Horne insists the changes, designed to more accurately reflect travel times, are "good news" for commuters.
But her Liberal shadow says the slower trains are a "disaster", given the billions spent removing level crossings to speed up train lines.
Public Transport Victoria has revamped the timetable after analysing how long it had been taking people across the network to get on and off the train.
Some services will run up to two minutes faster under the new schedule, which will come into force at the start of December.
Others will run up to three minutes slower, according to PTV's modelling.
The bulk of the changes have been made for the increasingly busy Cranbourne and Pakenham lines, with minor adjustments elsewhere.
PTV boss Jeroen Weimar stressed the state's rail network is carrying far more people now than it was a decade ago.
"What we're now doing is ensuring where we can have improved efficiency, we're building it into our timetable," he told reporters in Melbourne on Thursday.
"But where there is additional time needed for people to get on and off trains, we're also building that time into our current timetable."
Ms Horne said the changes are "good news" as commuters will be able to plan their journeys more accurately.
Neither Mr Weimar or Ms Horne would not say which or how many services would be slower or faster.
Victorians have instead been told to check the timetable when it is made public on Friday to see how their regular routes may be affected.
State coalition transport spokesman David Davis said the slower trains on the Cranbourne and Pakenham lines are a "disaster", given the government has spent more than $2 billion on improving them, including removing level crossings.
"The solution is to run the system properly. It is not to make trains take longer, it is not to slow down the trains," he told reporters.
Trains will also begin arriving at the city's Southern Cross Station about an hour earlier on Sundays, to help people using several lines move more easily between the night network and standard trains.
Australian Associated Press