Main Roads director-general David Stewart was yesterday sent to inspect the Sir Thomas Mitchell Bridge, which formed a vital part of the road link between Darwin, Mt Isa and Brisbane.

A spokeswoman for Main Roads Minister Craig Wallace said the department was “very worried” about the bridge and confirmed the federal government had already set aside $7 million for a new bridge.

“It's in the design phase now,” she said.

“Whether it gets fast-tracked or not depends on what they find as they flood-test the bridge over the next few days.”

Main Roads crews and a surveyor tested the bridge all day yesterday, restricting access in and out of Mitchell to short stints to allow supplies to pass.

Only light vehicles were allowed across the bridge, which is a key link in the Warrego Highway.

By late yesterday afternoon, a large crane was being used a heavy load on the bridge to test the supports.

Mr Wallace's spokeswoman said the Maranoa River was flowing too fast under the bridge for sonar engineering equipment, needed to check the badly-damaged bridge's supports, to be used.

Mitchell's senior emergency officer Inspector Graham Cooke confirmed Main Roads officers were worried about the bridge supports.

“This is the main link between Darwin and Brisbane,” Inspector Cooke said.

“It is going to have a big impact on town if they go ahead with it.”

Mitchell businessman Rob Attwood said it was time the town had a new bridge because of the growth in the coal and gas mining and for local tourism.

“Now is the time to do it,“ he said.

“We need to let the freight get through to Mount Isa and to Darwin and let all the exploration for the gas and the coal.”

Mr Attwood said few people understood how many large road trains used the bridge.

“Your triple road trains are your main freight vehicles out of Brisbane to supply all the mines up towards Darwin, Blackall, everything” he said.

“All the cattle that comes out of the channel country uses this point. They all use this bridge.”

Mr Attwood said while the Sir Thomas Mitchell Bridge appeared safe for light vehicles, many local businesses believed a new bridge was necessary.

“I think its safe to let small vehicles under five tonnes across it, but I wouldn't be letting road trains across it until they fixed it,” he said.