Improving Adelaide's maligned public transport system has been listed as a priority in the latest Infrastructure Australia Plan (AIP).

Key points: Urban congestion a 'key challenge' for Adelaide

Urban congestion a 'key challenge' for Adelaide Gawler passenger line to reach capacity within 5 to 10 years

Gawler passenger line to reach capacity within 5 to 10 years Insufficient funds to pay for infrastructure reform

It recommended completing the electrification of the Gawler passenger line and reinstating Adelaide's tram network in an effort to overcome urban congestion.

Adelaide had an extensive tram network covering all quarters of the city and inner suburbs until it was ripped up in the 1950s to make way for buses and cars.

An audit undertaken last year for the AIP released today found that the performance on urban roads and urban public transport in Adelaide was a "key challenge" for South Australia.

It flagged a tram network as a medium-term solution in the next five to 10 years, and the Gawler electrification as a near-term solution along with upgrading the remaining sections of the north-south road corridor through Adelaide.

SA Transport and Infrastructure Minister Stephen Mullighan said an Adelaide tram network, to be called AdeLINK, would "revolutionise" the city and encourage people to live alongside tram routes.

"But to get these projects moving we require cooperation and funding from the Commonwealth Government," he said.

Work was underway on the Gawler electrification earlier this decade but it was shelved in 2013 shortly after the Coalition formed government when it withheld a reported $76 million in federal funding from the project.

"The State Government has committed $152.5 million to begin electrification to Salisbury in 2017 and with a Commonwealth contribution the line could be completed sooner," Mr Mullighan said.

The AIP said demand on the Gawler passenger line was expected to nearly double by 2031, with Salisbury in northern Adelaide identified as the "second most frequented destination in greater Adelaide for rail trips".

The line's network is expected to reach capacity within five to 10 years.

The report found delays to upgrading Adelaide's urban transport network cost the country $1 billion in 2011, which would grow to $4 billion in 2031 "in the absence of investments or other changes beyond those already funded".

Adelaide's CBD was listed as the main public transport destination, but the proportion of passengers commuting via public transport was about 8 per cent, compared to 11.5 per cent in Melbourne and Brisbane, and 17.6 per cent in Sydney.

Other priorities for SA listed in the report included sealing the 472-kilometre Strzelecki Track in the state's north-east and improving the region's mobile phone coverage, improving the state's bulk port capacity, realigning the Sturt Highway through the Truro Hills, including a bypass through the town of Truro, and expanding the Boliver Wastewater Treatment Plant.

It also included improving rail line capacity between Melbourne, Adelaide and Perth, and laying a 350-kilometre railway line to the Gawler Craton mining province in the Upper Eyre Peninsula.

The plan set out 93 priority projects nation-wide for the next 15 years, which if implemented, is expected to boost the economy by $40 billion and leave the average household nearly $3,000 better off each year.

Funding the projects would prove to be a challenge, however, with the report released on the same day Federal Treasurer Scott Morrison is expected to reiterate the Government's commitment to reducing spending and implementing income tax cuts.

The report warned spending levels were insufficient to pay for infrastructure reform and recommended replacing car registration fees and fuel taxes with a user pays system for motorists to help pay for road and rail projects.

Stephen Mullighan said a user-pay system for all motorists would not be fair.

"I think there's a case to be made for people who are using the roads to drive an economic income, particularly truck drivers, and that's been the push behind network charge for heavy vehicle users," he said.

"But the rest of us aren't using the roads necessarily to generate our income, so it's a bit unfair to be charged a user pays system."