As the $274 million dollar Bateman’s Bay Bridge begins to take shape in southern NSW, Madsen Giersing has been working with the lead contractor John Holland to design and deliver a temporary works solution to support the existing bridge’s demolition.

Scheduled for completion in 2023, the new four-lane bridge, with its separate three-metre-wide cycleway and pedestrian walkway, is supported by concrete piles. The piers are located on top of the piles and rise 12 metres above the Clyde River.

A critical element of the removal of the existing bridge is the safe removal of the existing caissons.

Due to our experience in marine and temporary works, Madsen Giersing was charged with the structural fit-out of the barge and support frame used to move the caissons into place, providing IFC design drawings and design certification.

Managing Director Lasse Madsen outlined Madsen Giersing’s involvement. “This is a challenging project from a technical perspective. The process for caisson demolition appears straight-forward; an M16000 crane picks up the cut-down caisson and places it on a rotator on the barge, which rotates down onto the support frame lying each segment horizontally on the barge. The barge moves the caisson to the jetty, and the rotator self-levels back to the start position when the caisson is removed from the unit.”

“However, we are working with two different caisson specifications – 3.66m diameter and 3.05m diameter, with each being up to 10m in length and weighing up to 150 tonnes. Therefore we had to engineer a solution that would be able to adapt to the different sized caissons and distribute the combined weights of the crane and the caisson within the barge’s 20 t/m2 deck capacity. We were also working within tight environments and had to ensure that the rotator legs fitted between the crane mats,” said Lasse.