CONVERSION OF A SUSPENSION BRIDGE INTO A CABLE-STAYED BRIDGE

After many years of use, the Belgo suspension bridge, used to convey logs, was clearly in need of repairs. Because of uncertainty about the condition of the anchorages, it was decided to convert it from a suspension bridge to a cable-stayed bridge. This would produce the least disruption to the operations of the mill, while providing a solution to all the identified deficiencies. Although such a conversion has been proposed before, this is thought to be the first time it has been accomplished. The exercise provided valuable experience in the intricacies of altering a suspension bridge to a cable-stayed bridge, particularly during the period when the bridge is partly supported by both systems. The process is rendered more challenging by the requirement to keep the bridge operational for most of the construction period, and by the knowledge that stresses are already unacceptably high and must not be increased during the alterations.