Lobby group GrainGrowers has calculated what it says is the massive difference in the share of maintenance costs, when it comes to bridge upkeep.
GrainGrowers Trade and Supply Chains policy manager Annabel Mactier said a large percentage of Australia's regional bridge infrastructure was built over 50 years ago and was approaching the end of its operational life.
"The stark challenge facing regional councils is that while the cost of bridge maintenance in urban areas is typically shared between 4,934 people, in rural areas it is only shared by 142 people," Ms Mactier said.
"This means that far too often rural and regional road managers are unable to afford the cost of upgrading or replacing the bridges and are instead forced to implement load limits to protect their assets.
"For the grain industry, these load limits inhibit productivity by restricting the total weight a heavy vehicle can carry over the bridge, resulting in smaller and less efficient heavy vehicle combinations to transport grain."
GrainGrowers has previously said one in six Victorian bridges are in urgent need of upgrading.
The group said a recent additional $20 million federal government bridge renewal funding was welcome.
But Ms Mactier said there was a need for additional urgent targeted funding, to address safety and efficiency issues in the May 14 budget.
At the same time, councils last year identified the soaring cost of construction, as having a significant impact on bridge construction and repairs.
Grain and pulse grower Brian Barry junior, Manangatang, said freight costs were soaking up a large part of the value of commodities.
'We are paying $60 a tonne to get freight to port, anything that can free that up, the better - $60 a tonne out of $300 is a pretty big percentage," Mr Barry said.
One of the worst bridges in the region was the Swan Hill to Tooleybuc crossing, on the Murray River.
"It should be in a museum, it's a horrendous old wooden, single lane thing," Mr Barry said.
The state of the bridges across the Murray resulted in restrictions in machinery, passing between Victoria and NSW, as well, he said.
"There would be more steel on the bracing than there would be wood, it was built back in the paddle steamer days," he said.
Livestock and Rural Transporters Association of Victoria president Russell Borchard said while the Performance Based Standards (PBS) network had been expanded, a significant number of bridge load limits were still in place.
The PBS "disconnects" heavy vehicle design from prescriptive limits like height, weight and length.
"We can't get anywhere at full weight," Mr Borchard said.
"It's supposed to be about productivity and it's not increasing productivity - trucks have to go out of their way, you've got to apply for extra permits to go off the road to find a way around the bridge," he said.
He said weight limits were imposed to increase the lifespan of the bridge.
Governments also needed to re-examine how bridge limits were assessed, as the standards were set "years ago"
Vehicle weight was now measured with greater accuracy, ensuring overloading was not occurring, he said.
"The truck is declaring its weight, as its driving down the road, so there is no risk of those trucks overloading," he said.
Veteran Tarranyurk grain farmer Marshall Rodda said when b-Doubles first came in, "you'd have to do a bit of a billy goat track around, to dodge bridges".
"The main one that I have a concern with is in Warracknabeal and the two bridges over the Yarriamback Creek, and in today's modern world they are not up to the standard for the traffic that comes through the town.
"Grain traffic comes in all year round, once upon a time you only had small trucks coming in at harvest time, now we have got grain trucks running all year around.
'We have a livestock selling centre that runs fortnightly, so you also have stock movements."
One of the bridges in the town was a single lane crossing and "it's absolutely dangerous".
"But there are three people with their finger in the pie - you've got the shire which looks after the bridge, the water board, which has a weir against it, and the environmental people who don't want you to put another bridge over everything, so it makes it more difficult," he said.
"It's all about the money, it doesn't matter what you do - probably 45 years ago there was a plan to build a town by-pass with a new bridge, but it never got off the ground."