By staff writers
A retired engineer who worked on the construction of the Barron River bridge in 1962 said the concrete
structure had outlived its useful life which has been known by the State Government for more than four years.
Due to potential catastrophic failure, the downgraded weight limit now at 50.5 tonnes would soon have to be lowered again because the bridge is in the final days of its life. It has been estimated the cost of a new bridge could be up $500M.
The engineer, who wished to remain anonymous said when the bridge was built 58 years ago there was no comprehension it would be carrying the large volume of heavy loads at the speed of modern trucks today.
“The life of the bridge was supposed to be 100 years but it takes one third of its life for the concrete to cure, another third for maximum carrying capacity and in the final third it starts to deteriorate,” he said.
X-rays taken in 2016 indicated each pier had a multitude of fine cracks which could be repaired by external application or drilling holes in the structure and pressure-filling them with a low viscosity, two-pack epoxy bond.
To start this treatment first each pier has to be X-rayed which takes at least six weeks then six months to inject the epoxy into each one.
Drilling could weaken the pier structure therefore it had to be done one by one or the integrity of the entire bridge could be affected.
But the downside to this remedy is that the concrete in the pier becomes rock hard and loses flexibility which is required for heavy, moving vehicles.
It is vibrations that cause cracks so the weight and speed limits would have to be lowered significantly to reduce this movement, he explained.
“Vibrations from speeding vehicles over previous years have created the fractures in the concrete which were discovered in 2016 and the next report will probably show it is in worse condition,” he said.
In 2019 the Main Roads Department awarded multi-million dollar tenders for the repair of four concrete bridges on the Mulligan Highway between Mount Carbine and Lakeland because of similar deterioration.
These repairs took nearly 12 months to be carried out. The Barron River bridge could take two and one half years to fix.
Meanwhile a much-publicised alternative road, the Bridle Track, to Cairns from the Tablelands which bypasses the dangerous Kuranda Range Road and the Barron Bridge is being ignored by local Labor Members of Parliament, Craig Crawford and Cynthia Lui who have known about the poor state of the bridge for some time, certainly before the October state election when it was not ever mentioned.
All northern Labor politicians have studiously ignored the problem. Crawford’s thought bubble solution to the accident-prone Kuranda Range Road was to put all travelers into driverless cars and trucks.
After all Crawford and Lui represent the Labor Party, not the people.