The days of getting a seat on a Melbourne train will soon be replaced by the kind of shoulder-to-shoulder commute people experience daily in mega-cities such as Tokyo.

Designs for a planned fleet of 65 new high-capacity trains that will enter service from mid-2019 reveal a radical change is in store for Melbourne train travellers.

The trains will be built to carry between 1200 and 2000 passengers each, depending on their configuration, and they will be designed to maximise standing room, with seats provided for just 30 to 40 per cent of passengers in a fully loaded train.

The bumper loads will be accommodated by enabling "standing passengers to safely travel at a density of up to six passengers per square metre", technical documents seen by Fairfax Media say.