Bridges

As part of Victoria's Big Build, the Princes Highway between Traralgon and Sale is progressively being duplicated to improve road safety and reduce travel times. Currently, the Princes Highway east of Kilmany spans over the highly skewed Melbourne to Bairnsdale railway line operated by V/Line. To minimise the disruption to both road and rail users, a key requirement for this project, it was proposed to realign the highway and replace the existing overpass with a highly skewed single span railway bridge which could be constructed offline without prolonged rail occupations nor extensive temporary and permanent retention systems. The traditional solution for long single span railway bridges is a truss or tied arch bridge with either vertical or inclined hangers in the Nielson arrangement. Tied arch bridges of this form experience large longitudinal bending in the deck and arch members leading to heavy steelwork. An innovative network arch bridge was proposed for this project over more conventional solutions. A network arch is a tied arch bridge with inclined hangers that intersect at least twice. These regularly spaced inclined hangers cause the bridge to behave like a truss with its members subject to axial forces and minimal bending. This structural system is extremely stiff, efficient and is aesthetically appealing with a lightweight and slender form. This paper will explore the outcomes of the Design Development phase of the project where numerous design solutions were evaluated and explain why the network arch bridge form was selected. Key underlying concepts, the unique features and particular design considerations for this bridge form will then be discussed to inform future designs in Australia.