A proposal to charge truck companies a "network charge" to use roads is still being worked through by the Federal and South Australian governments in a bid to channel cash into the road network.

Premier Jay Weatherill earlier this year offered for the state trial elements of the proposal, which if successful would be rolled out nationwide.

The national proposal is seen as a strategy to improve the country's freight transport infrastructure.

Federal Assistant Minister for Infrastructure and Regional Development Jamie Briggs said the system could apply from about 2019.

Mr Briggs said the Federal and SA governments had agreed to work together on the proposal.

"What we're going to look at is whether we can put a system together which uses just the user charge against those other inefficient taxes and apply that, so that is the agreement we've reached," he said.

He also ruled out a toll on Adelaide's Northern Connector road.

Transport Minister Stephen Mullighan told ABC 891 Adelaide's breakfast program the "network charge" would replace a range of fees and charges including registration, a road user charge as well as fuel excise.

"The concept of a network charge is to do away with all of those charges and replace it with a single charge that is based on the distance a truck travels on the road network and the quality of road that they are travelling on," Mr Mullighan said.

"So it is far more accurate and transparent for the truck operators.

"We've concentrated on the heavy vehicle industry for two reasons. One is, they are the ones who are ... getting an economic return out of the roads.

"They are making their living out of the roads and they are also the one who are doing most damage to the roads with their heavy loads."

He said both levels of government had "a genuine desire" to find a more sustainable funding mechanism for roads.

Details including which government would collect the charge and how the money would be divided are yet to be decided.

Business SA chief executive Nigel McBride said the lobby group welcomed news there would be no tolls on the new road.

"We look forward to being consulted by the State Government regarding its proposal on heavy vehicle charges," he said.

South Australian Road Transport Association's Steve Shearer said the industry would not accept the proposal if it left trucking companies worse off.

"We already overpay, governments know that," he said.

"A key parameter of this work and the trials we're starting to develop we will not pay more.

"There has to be a rebate from the existing charges otherwise we won't play," he said.