Melbourne's train commuters will receive no immediate relief from the peak-hour crush, with no plans to significantly boost train timetables until at least the end of the year.

The last major timetable change was June 2014, despite demand for train travel growing by 6.5 million journeys a year and peak-hour overcrowding worsening on the city's busiest lines.

The Andrews government has allowed the overcrowding problem to fester despite opening the Regional Rail Link 13 months ago, which created the capacity to run an extra 23 peak-hour trains between the city and the fast-growing northern and western suburbs.

Those extra trains were planned to run on the Werribee, Craigieburn and Sunbury lines, three of the four worst lines in Melbourne for peak-hour crushes. They would have enabled an extra 54,000 passengers to access public transport.