Melbourne's most crowded trams are on the inner-northern routes of 1 and 6, according to a new state government report, which also claims overcrowding is rare and the commuter crush at peak times is improving.

But public transport advocates have criticised the report, saying it misses the real story of overcrowded trams in the CBD by cherry-picking survey locations to deliver more favourable results.

Commuters on a packed tram on Bourke Street on Wednesday. Credit:Chris Hopkins

The transport department's annual tram load report, which surveyed passenger volumes over a nine-day period in May, found only four instances of CBD trams that were over-capacity during peak times.

Public Transport Users Association spokesman Daniel Bowen said the explanation for the rosy report could be found by looking at the map of survey locations.