More than 78,500 people in southeast Queensland now take a free bus, train or ferry trip each week after the Newman Government introduced their "free trips after nine journeys" policy in June 2012.

Since that time there have been 7.1 million free journeys on southeast Queensland's public transport system.

Buses are a key part of Brisbane's transport infrastructure. Credit:Michelle Smith

However Transport Minister Scott Emerson said there was little evidence of commuters rorting the system, an issue raised consistently by rail lobby group, Rail Back on Track.

Mr Emerson said there was only a slight increase in the percentage of commuters using the nine free journeys early in the week.