Melbourne transport and planning expert Paul Mees has died following a 15-month battle with cancer.

Professor Mees, who taught at RMIT, was aged 52 and died on Wednesday in a Melbourne hospital.

Paul Mees. Credit:Michael Clayton-Jones

An international authority in his field, Professor Mees for more than two decades repeatedly embarrassed Victorian transport operators and authorities with his research and commentary on the state's road, rail and urban planning systems.

Most recently, he had questioned the Napthine government's proposed east-west tunnel, arguing there was little substantial research behind the $6-8 billion project.

A former industrial lawyer, Professor Mees was the president of the Public Transport Users Association from 1992 to 2001.

In 1998, he began teaching urban planning at Melbourne University - only to fall out with the university a decade later after it demoted him following a complaint against him by the state government.

The PTUA's president Tony Morton said on Wednesday night that Professor Mees had for many years "personified the transport debate in Victoria, and called successive governments to account for their neglect of public transport".