More caravans have lost their air-conditioning units in recent time after hitting the 2.7 metre high rail under bridge, says Chris Mills.

Debris from the units and other over-size vehicles that have come to grief is scattered on both sides of the structure.

She highlighted a Dash Cam Owners Australia Facebook post showing a motorist driving south along Garroorrigang Road. An oncoming vehicle towing a caravan emerges in the distance and negotiates the underpass, only to have its air-conditioning unit on the roof smashed to pieces.

The dash cam owner lets out an expletive. The post has since been shared 447 times and attracted 981 comments.

Mrs Mills says it does little for Goulburn's reputation.

"We don't want to be remembered for costing someone up to $3000 to replace their air-conditioner," she said.

"...Surely we can do more...If we put up signs directing caravans over the Mundy Street bridge, it would be far better."

She told The Post that GPS technology was erroneously directing travellers via the under-bridge and suggested the council should seek to rectify this.

Mrs Mills said she and her husband saw a car and caravan pulled up on the southern side of the underpass on Good Friday morning. The driver had fortunately seen the 2.7m clearance sign and was pondering how to turn around.

"We told them which way they could go but we shouldn't have to do that," she said.

Toowoomba couple Lawson and Janet Rennie weren't so lucky before Christmas.

Mr Rennie said he used the GPS to navigate from the Hume Highway south of Goulburn to Braidwood Road.

"We came to the T-intersection (Mazamet and Garroorigang Roads). I didn't see the sign (warning of the low clearance) but my wife did. We drove down through an S-bend and then heard a crunch. The bridge took the air-conditioner straight off the top of the van," he said.

"Fortunately we were able to get it fixed in Fyshwick that day and insurance covered it."

The replacement cost the couple $1000.

Mr Rennie believed the signage should have been larger and more prominent and further up the road and referenced other points on his trip where this was the case.

"The signs obviously aren't doing the job," he said.

The council's traffic road safety officer Tracey Norberg said the issue arose at the February traffic committee meeting.

"It is considered that the signage installed on approaches to the underpass bridge warning of the height restriction is sufficient," she said.

"The council has also made contact with Google Maps regarding re-directing caravans and trucks away from the underpass but as yet have not had a response."

Signs have been erected at eight points around the bridge.

The council's traffic committee chairman Cr Andrew Banfield said the issue had emerged many times at meetings.

"I'm not sure how many signs we need...They are very clear as you come off (the feeder roads)," he said.

Cr Banfield has received about six phone calls about the issue. He said he'd propose signage further up Mazamet Road at the next traffic meeting to give motorists greater warning.

He maintained that drivers of caravans and trucks, some of them local, were simply forgetting about the size of their vehicle.

"It's also the poisonous gases that come out of the air-conditioners. You just can't let that go into the atmosphere," he said.

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