A report by Monash University public transport expert Professor Graham Currie found the "early bird" promotion - free travel for those arriving at their destination before 7am - had shifted about 2600 passengers each day out of peak travel times onto trains that were otherwise near-empty.

Professor Currie told the Journal extending the early-bird program to 7.30am could further reduce overcrowding during the "peak of the peak".

He also said more passengers could be encouraged to travel early by paying them or providing discounts on future travel through the Myki system in a move that would still save the Government money.

Professor Currie's report revealed 23 per cent of early-bird passengers had shifted their travel time by an average of 42 minutes to take advantage of free travel.

If early bird travel was extended to 7.30am, an extra 2000 to 4000 passengers normally arriving at 8.12am would be likely to travel earlier.

Under Professor Currie's scheme, there would be an extra free Belgrave service - leaving at 6.03am. Currently, the latest free service leaves at 5.42am. There would be two extra services from Lilydale, at 6.02am and 6.16am, and four from Ringwood, between 6.18am and 6.41am.

"No other method could this quickly ease the impacts of overcrowding," Professor Currie said.

He said the only other way to solve Melbourne's public transport crisis was to buy at least five new trains at a cost of $20 million each. The trains would also cost $1 million a year to run and take about five years to manufacture.

The report showed Melbourne's rail ridership had grown by more than 40 per cent in the past three years but peak-time overcrowding had "limited the performance and the economic and environmental benefits that rail provided".

A State Government spokesman said there were no plans to extend the early bird scheme, which had shifted the equivalent of 21/2 train loads of passengers from morning peak-time travel.