Fix road, rail plans: infrastructure boss

Federal and state governments have been urged to stop putting populist politics ahead of sound road and rail planning or risk increased congestion in Australia's capital cities.

Infrastructure Australia chief Philip Davies has launched a critique on the "gold-plating" of projects without proper business cases, saying better planning was needed to cope with population growth.

Mr Davies told The Australian an additional 11.8 million people will call Australia home in the next 30 years.

"The reality is, if we don't improve the way we plan and deliver our infrastructure, we won't cope with this growth and our cities will be characterised by congestion and constraint," he said on Tuesday.