Forgan Bridge

In 2010 Southern Cross demolished the Forgan Bridge in Mackay Qld. This bridge was one of our most challenging bridge demolitions yet. Not only was the concrete structure 485 metres in length and within one of Australia’s pristine blue marine water parks, Southern Cross was also required to demolish the bridge in a strict time frame as our principal contractor (Golding Contractors) was following immediately behind us with the construction of their new bridge. During the demolition we also encountered six metre tide swings, two cyclones and floods that impacted on our in-stream barge operations.

The bridge consisted of 34 concrete reinforced spans and had several different pile types to be removed being cast iron, concrete filled, steel reinforced with concrete filled and concrete reinforced piles. Over the years modifications had to be made to some of the bridge pile caps due to it sinking into the river bed below. Additional heavy reinforced concrete was added to the pile cap structures to alleviate this problem. This additional heavy reinforcing meant that controlled blasting was the optimal solution to allow us to fracture and remove the pile structures.

Southern Cross worked on this project with 15 personnel divided into two teams being the superstructure team (land based) and the substructure team (marine based). The superstructure team demolished the decking using excavators attached with hydraulic rockbreakers. The concrete decking was systematically hammered down and contained within a catch barge below. The material was later removed by a barge mounted skid steer and transferred by excavator back to the deck of the following span where it was transported to a recycling centre.