In a partnership with the Hodgman government, the Coalition has committed to contributing $64 million of the $80 million earmarked for the key freight route.

Deputy Prime Minister and Infrastructure Minister Michael McCormack said the funding would allow for a shorter, more attractive route for both freight and passenger vehicles travelling on Illawarra Main Road, between the North-West and Southern parts of the state.

"Illawarra Main Road carries a high proportion of heavy vehicles at more than 15 per cent of total traffic volumes and the freight task along this road is forecast to grow from 1.6 megatonnes to 2.2 megatonnes per annum in the next 10 years," Mr McCormack said.

"The Illawarra Main Road is a great example of a vitally important regional road that needs investment to improve productivity and to get people home sooner and safer."

Lyons Nationals candidate Deanna Hutchinson said the upgrades would be completed in two stages.

"Our commitment is to prioritise construction on widening, improving and adding protected overtaking lanes to the section from the Bass Highway to Longford, with a federal injection of $60 million," she said.

"We will also provide $4 million to ensure planning and design is underway for the section from Longford to Perth, including consideration of the Longford roundabout and the bridges over the South Esk River at Longford and Perth, in parallel to the completion of Perth Link Roads in 2021."

State Infrastructure Minister Jeremy Rockliff said the Illawarra Main Road was a major connection in the North-South supply chain.

"Along with the $500 million Midland Highway Action Plan and the $240 million Tasmanian Freight Rail Revitalisation Program we are rebuilding key freight and commuter corridors and supporting Tasmania's productive industries," he said.

"When it comes to significant infrastructure funding, the federal Liberal-National Coalition has delivered record investment in Tasmania, and we welcome this commitment to upgrading Illawarra Main Road."

In terms of other roads funding the major parties have announced, the Liberals have pledged $40 million to upgrade the hairy Sideling road on the Tasman Highway, while Labor has committed $25 million.

Labor's Sideling promise is part of an overall $150 million roads package for the state, including proposed upgrades to the West Tamar Highway, the Frankford Highway and the Bass Highway.