Australia's independent infrastructure adviser has warned the rail link between Sydney and Canberra must be improved in the next five years, strengthening longstanding calls from the ACT and NSW governments for serious investment in the corridor.
Infrastructure Australia has also renewed a call for the corridor to be preserved for high speed rail, as part of a line down the east coast of Australia.
The body has identified a $58 billion pipeline of projects needed across Australia over the next 15 years, including 37 new projects across the water, energy, health, waste, transport and telecommunications sectors.
The 2020 list - its largest ever - has an increased focus in addressing the risks and effects of climate change.
Infrastructure Australia chair Julieanne Alroe said the recent bushfire and flood emergencies made it clear Australia's infrastructure networks faced "unprecedented risks".
"Climate change brings with it higher temperatures, unpredictable seasonal rainfall and water availability, more extreme winds, more extreme weather events and bushfire seasons the likes of which Australia has never seen," she said.
"Australia's emissions are among the highest in the world in per capita terms and our infrastructure accounts for more than half of the national total.
"Making our infrastructure more sustainable will be critical to protecting the quality of life of Australians."
The body said urgent action needed to be taken to improve connectivity and reliability in the National Electricity Market in the medium to longer term.
It also included on its list for the first time improvements to the Canberra to Sydney rail link, off the back of submissions from the ACT and NSW governments.
It takes more than four hours to travel between Canberra and Sydney via the 320-kilometre rail line, compared to three hours by car and one hour by air. As a result, only 1 per cent of people travelling between the cities do so by train.
Infrastructure Australia's senior economist Rob Busch said their assessment found the issue was "nationally significant" due to the congestion, lost productivity and lost opportunity it caused.
Infrastructure Australia said the travel time could be made quicker by straightening and duplicating the track, electrifying and upgrading signals and investing in new rolling stock.
"The number of people living between Canberra and Sydney is forecast to grow by 1.5 per cent each year to 2036, increasing pressure on the road network and airports.
"Improving rail services in this corridor would provide more transport options for travellers, improve travel-time reliability for rail passengers and reduce pressure on the air corridor."
The call adds weight to the longstanding push to improve the rail connection with Sydney.
The ACT and NSW governments have each put up $5 million to investigate upgrades to the line.
The Infrastructure Australia list also identified bus transit lanes between Belconnen and Civic and Queanbeyan and Civic as a priority for the ACT in the next five to 10 years.
The bus transit corridors have been on Infrastructure Australia's priority lists since 2016, due to worsening congestion.
Belconnen and Canberra Airport will eventually be connected by stage three of light rail, but with stage two of the project to Woden yet to break ground, that will be some years away.