Construction is underway to upgrade a critical section of the Midland Line to boost grain-to-port rail freight capacity in Western Australia's Mid West region.

Arc Infrastructure is upgrading approximately 78 kilometres of track on the Midland Line between Carnamah and Mingenew.

The works will see the replacement of timber sleepers with about 55,000 modern concrete and steel sleepers to increase the tonne-axle load (TAL) from 16 to 19 tonnes.

Once complete, the project will streamline grain handling, boost capacity and deliver savings on freight costs to local grain growers by increasing the amount of grain that can be carried on a single train by 25 per cent.

The Midland Line plays a vital role in transporting grain to Geraldton Port, with CBH Group using the corridor to transport about half a million tonnes of grain annually.

In consultation with CBH, Arc Infrastructure has temporarily closed the line to undertake the construction, with the project expected to be complete by early next year.

This project is funded through the $200 million Agricultural Supply Chain Improvements (ASCI) program, towards which the Albanese Government is contributing $160 million and the Cook Labor Government $40 million.

As part of the Midland Line upgrade, the Australian and Western Australian Governments are contributing $45 million through ASCI for the design and purchase of construction materials, with Arc Infrastructure contributing $22 million for construction works.

ASCI is delivering a number of projects in WA's grain-growing regions to support regional communities and economic growth.

These include rail siding upgrades already completed at Cranbrook, Moora, Brookton, Broomehill and Konnongorring.

Quotes attributable to Federal Infrastructure, Transport, Regional Development and Local Government Minister Catherine King:

"Through our Agricultural Supply Chain Improvements program, we are building greater capacity and efficiency moving WA grain from farm to port, now and into the future.

"The Australian Government, working with the WA Government and industry, is delivering a legacy of more resilient and productive rail freight infrastructure for the regions."

Quotes attributable to WA Transport Minister Rita Saffioti:

"The Midland Line is a critical link in Western Australia's freight supply chain, so it's important it's future-proofed so we can keep our State moving.

"These upgrades will enable more grain to be transported by rail, supporting productivity and delivering greater returns for growers.

"The Cook Labor Government is committed to improving capacity and efficiency across our State's rail freight network to support local jobs and keep our economy strong."

Quotes attributable to WA Agriculture and Food and Mid West Minister Jackie Jarvis:

"Western Australia's grain industry is a powerhouse of our regional economy, and the Mid West plays a vital role in producing the premium grain we export to the world.

"Upgrading the Midland Line between Carnamah and Mingenew supports better returns for local growers, and will help WA remain competitive in the international market.

"These works are another example of how the ASCI program is strengthening our grain supply chain, and supporting WA growers, regional communities and the State's economy."

Quotes attributable to Senator for Western Australia Glenn Sterle:

"By investing $160 million for rail in WA's grain-growing regions, we are future-proofing our freight network.

"This means less heavy traffic on our local roads and more grain safely making its way to the market, while backing local jobs and supporting farming communities."

Quotes attributable to Sandra Carr MLC:

"The Mid West region is a significant driver of Western Australia's economy, producing millions of tonnes of grain each year.

"By upgrading the Midland Line between Carnamah and Mingenew, we're investing in the future of this important industry that supports so many local jobs and families.

"Projects like these are part of the Cook Labor Government's commitment to delivering quality infrastructure to support our regional communities and economy."