The State's grain freight rail network is days away from grinding to a halt, with CBH and Brookfield Rail still at odds over an interim access deal.

CBH has back-up plans to cart all grain from country storage facilities to port by truck if the deadlock is not broken by Thursday, when the current access agreement with BR expires.

Farming a tale of two regions

The WA farming co-operative has been keeping its customers up to date on the negotiations and its alternatives for filling a crowded shipping calendar.

The last interim access deal with BR - which has an exclusive lease over the State-owned rail network - was signed the day before it was due to expire.

The parties appear further apart this time around, raising fears that thousands of extra truck movements could soon hit WA roads.

The stakes are also higher, with CBH and BR in unchartered waters under WA's Railway (Access) Code as they try to thrash out a lasting deal. Those talks have been pushed to one side as time runs out to strike an interim deal to keep grain on rail.

CBH is adamant access for its fleet of locomotives and wagons should be extended on like terms while it pursues a long-term agreement under the code. It said BR wanted to increase access rates by up to 30 per cent on top of a recent rise in line with CPI.

BR said it was not shying away from the need to increase charges and for CBH to pay for access at close to the "market rate", particularly if it wanted to lock in significant capacity on the busy Eastern Goldfields Railway.

"Our view is that it (the increase) is affordable," BR chief executive Paul Larsen said.

Mr Larsen said the proposed increase represented about 0.5 per cent of the commodity price based on the volume of tonnes carted by rail last year.

CBH operations manager David Capper said the grain handler wanted a new interim deal based on existing terms.

"Extending on like terms with an annual escalator is the fairest and right way forward," Mr Capper said.

"We'd like to pay less, but what we think is fair and reasonable is like terms."

Mr Capper said neither party wanted to see all grain freight in WA pushed on to roads, but CBH would not agree to rail access terms that disadvantaged its 4200 grower members.

"We won't agree to anything we can't afford because it isn't the right outcome for growers," he said. "We'll use the most efficient mix of transport to deliver the freight rate we promised to our growers." On the line 8.3 The record number of tonnes, in millions, carted by CBH on lines controlled by Brookfield Rail in 2014.