TWENTY years ago a sign on the Murwillumbah Kyogle Road declared it was "the worst main road in NSW."

This morning a short distance from the site of the former sign, which had been erected by campaigners for a better road, Tweed mayor Barry Longland officially opened a new concrete bridge replacing one of the last old timber bridges on the route to Kyogle.

Not only is the entire road now sealed, with no car shaking ruts, but on the Tweed Shire side the last timber bridge has gone and the worst twisting curves straightened.

Cr Longland shared the opening on the Tom Grant Bridge near the Mt Burrell shop with descendents of Mr Grant - a pioneering farmer who lived nearby and put up with tough times and tougher roads.

"As a Uki resident myself, I'm aware of the history of the South Arm, and can only imagine how tough life was for pioneering families like the Grants," Cr Longland said.

"Although times were often hard and the farmers and their families worked even harder, there was still plenty of time for an active and fulfilling community life.

"From what I understand, Tom Grant was at the centre of community and civic life in the Mt Burrell area from the time he arrived in 1925 to when he retired to Kingscliff in1963.

"He too was a local councillor, serving on the former Shire of Tweed council from 1945 to 1946."

Cr Longland shared the official ribbon-cutting for the $1.2 million bridge over Snake Creek with three of Tom Grant's eight children - Dot Lange of Bray Park, Bernard Grant of Tweed Heads and Jack Grant of Murwillumbah.

His one other surviving child Alice lives at Emu Park in Queensland and was unable to attend today's event.

"He was an extraordinary man and very well respected in not only the Mt Burrell area, but the broader community," Mrs Lange said.

"He was a decorated soldier from World War 1, an avid letter writer to the Tweed Daily News, a self-educated but widely-read man and a secretary of many organisations.

"Personally, our mum and dad instilled in all of us children our principles which have held us in good stead all our lives."

The bridge is a single 20m span concrete structure built on the site of an earlier bridge which had washed away.

Council staff said this avoided the costs and inconvenience to motorists of a temporary traffic bypass.

They said it was the first time this type of bridge design has been used in the Tweed, as it is a combination of the Queensland Main Roads and the NSW Roads and Maritime Services standard for bridges.

Funding for the bridge structure was split 50/50 between the council and NSW Roads and Maritime Services under a timber bridge replacement program.

"A lot of thought and planning has gone into this bridge in regards to the environment and an additional $40,000 was spent on environmental safeguards," Cr Longland said.

"A single span was used to save a pile being driven into the centre of the creek, which would have obviously had detrimental environmental effects.

"An ecological assessment found a number of threatened plant and animal species, including the Giant Barred Frog, the Fine-Leafed Tuckeroo, Hairy Joint Grass, and the Little Duroby.

"A great deal of care was taken to ensure there was no damage to these communities in the construction of this bridge.

"The deck arrangement of the bridge is now perfect habitat for the threatened Large-Footed Myotis (a bat), so bat boxes have been installed and I'm pleased to say that these boxes are now home to a small colony."