A 2019 submission to the state government, by the five councils in the south-west dairy region, asked for $317.5 million a year, over 10 years, to upgrade and maintain roads across the area.

Webber and Chivell Fertilisers managing director Andrew Chivell, Cobden, said maintenance costs for the company's trucking fleet were huge.

"For a long time now there's been a road we travel on daily (the Lavers Hill-Cobden Road), which was having a massive impact on our truck suspension," Mr Chivell said.

"There were potholes, there were washaways, there were narrow shoulders, bumps a foot deep, humps and hollows.

"It's probably taken us five years campaigning and doing the dairy study (submission) to get it done up."

The final speed limits were only removed about a fortnight ago and Mr Chivell said he would now be measuring the savings on suspension wear-and-tear costs for trucks using the restored route.

"It was just flogging everything out, suspension, springs - we had to rebuild the suspension every three to four years on those trailers," he said.

The Chivells run 25 trucks and trailers, supplying fertiliser throughout south-west Victoria.

Mr Chivell said it was a frustrating process to get the message across, as it took time away from operations.

"We have businesses to run, why can't we have a system where we talk to the shire and the shire actually gets listened to?," he said.

The Barwon South West Dairy Supply Chain Study, commissioned by the councils, estimated the region was responsible for 24 per cent of Australia's milk production.

"The freight task needed to transport production inputs, milk and final goods to market is significant and costs industry around $345m a year - around 29pc of total expenditure," the study found.

The study estimated achieving a 20 per cent increase in production and processing by 2045 would require an additional 47pc of gross tonnage (dairy inputs, milk and products) to be carted across the network.

Improving the roads, and a greater use of high productivity freight vehicles, would result in a reduction in haulage costs of $4.93 a tonne.

"One milk processor has reported facing increasing costs including a need to replace all springs and suspension components every 12 months, still experiencing breakages in between," the report found.

The report called for increased funding for resurfacing, rehabilitation, widening and strengthening bridges.

Mt Noorat Freighters manager Scott Guthrie said the company ran about 20 trucks and trailers, supplying stock feed to the region's farmers.

"We are replacing parts on trucks and trailers more regularly than ever, some parts you never had to touch for the life of the truck," Mr Guthrie said.

That was compounded by current supply chain issues, in getting replacement parts.

"We have been saying this for years - we are meant to supply a safe workplace but we are putting people out there in unsafe conditions, on the roads they have to drive on," he said.

Mr Guthrie said he'd been on "three or four different committees" to address the issue in the past 15-20 years but hadn't seen much change.

"You get pulled up by the heavy vehicle squad, VicRoads or the police and they are putting defects on your truck because they say it's not safe," he said.

"But the majority of the problems are caused by the roads we drive on."

Department of Transport Barwon South-West regional director Michael Tudball said the government had delivered a multi-million package of works across the south-west, in its efforts to support the dairy industry.

"These projects are part of a four-year $17.4 million investment announced at the 2020/21 Victorian Budget, that provides a more efficient road network for one of the region's largest industry employers," Mr Tudball said.

The department said it had targeted significant dairy routes, across the south-west, to assist freight operators and farmers across processing facilities and depots.

This included sections of the Cobden-Warrnambool road, Cobden-Stonyford road, Cobden Camperdown road and the Princes Highway.

Work had included rebuilding, resurfacing and widening roads so those key routes could support High Productivity Freight Vehicles (HPFVs) and increased trucking movements.