Flood immunity 100-fold

Another Northern Queensland community is now benefiting from vastly improved flood immunity with the replacement of a low-level, 1930s timber bridge on the Kennedy Highway in the town of Innot Hot Springs with a new, higher-level Queensland Department of Transport and Main Roads (QDTMR) pre-cast concrete bridge manufactured by Rocla.

“Rocla supplied 26 x 15m pre-stressed piles and 57 x 21m deck units for the new 3-span bridge which will improve the flood immunity to annual exceedance probability of 1% – which under the old terminology is equivalent to a 1 in 100 year flood event,” said Philip Pearson, Engineer (Civil) for the QDTMR Far North District Program Delivery & Operations.

The project is funded by the Australian Government and is part of a major push for continued works to improve the inland route that is used as an alternative to the Bruce Highway.

With a very low flood immunity, the original bridge had flooded a number of times in recent years, isolating the communities it served and putting a stop to heavy vehicle transport.

Philip says the QDTMR looked at a variety of replacement options.  “We undertook a geotech analysis of the ground strata and cast insitu piles were considered, but it was found that we could achieve the required capacity from pre-cast driven piles, which is a quicker method of construction with less risk when considering the close proximity of Rocla’s depot,” he said.

The project also involved upgrades to the bridge approaches and associated intersections, plus lighting and a pedestrian walkway on the bridge meaning big benefits for Innot Hot Springs residents and heavy vehicles looking for alternatives to the Bruce Highway during the wet season.

Bryan Vance from Brisbane-based contractor Decmil Engineering had worked with Rocla®  precast piles before. He agrees that you can’t ask for more than a project to go
to plan and for everything to fit together.  “It went smoothly, everything arrived on time and there was minimal hassle,” he says.  “The units were good quality, the post stressing holes lined up well and the lengths were all good.”

“Rocla in the past has provided The Department with very good pre-cast piles and deck units and we were able to continue that strong relationship,” said Philip. “Everyone worked well together to ensure the piles and deck units were delivered and installed on time and safely.”

This project is another example of quality improvements to QDTMR infrastructure delivered by Far North Queensland suppliers.