A GLIMPSE of what Melbourne's train timetable could look like 10 years from now has emerged from a government study into building a new rail line to Monash University and Rowville.

It reveals a plan to run trains as often as every four to five minutes in rush hour on some metro lines, and once every 10 minutes outside the peak.

The 'train service plan'.

The three-page ''train service plan'' for the year 2021 was published as an appendix to the lengthy government-commissioned Rowville Rail Study. It also gives an early peek at projected increases to V/Line trains to Geelong, Ballarat and Bendigo once the $5 billion regional rail link opens in 2016.

The future timetable plan was uncovered by the Public Transport Users Association, which welcomed the projected boost to services but questioned why the plan was buried deep within a voluminous report.