Bridges

This paper presents the design, fabrication, and installation of an innovatively shaped precast posttensioned girder system employed to widen an existing footpath over a rail corridor in St Leonards, as part of the Wadanggari Park development project. The bridge spans the existing corridor and abuts an existing Pacific Highway Bridge without imposing any additional load on the original bridge
structure. The existing bridge was not originally designed to accommodate any widening and changes in rail side clearance requirements meant that the original span configuration could not be replicated.

The project utilised a segmental construction method for the girder, enabling efficient transportation into a CBD environment. The girder, spanning approximately 32 meters with a walking surface
width of up to 2.5 meters, was designed with a distinctive L-shaped cross-section. This design allowed the structural depth to be primarily above the deck surface level, adhering to stringent vertical clearance requirements over the rail corridor while matching the existing footpath levels of
the adjacent existing bridge. Installation was carried out using a two-point lift executed with a tower crane and a mobile crane.

The widened footpath significantly enhances pedestrian flow and safety in a burgeoning urban environment which has recently undergone significant development and provides a waiting area for commuters at the adjacent bus stop.

This innovative solution demonstrates how modern engineering techniques can extend the functionality and lifespan of existing infrastructure, offering a cost-effective and minimally invasive alternative to full bridge replacement.

The paper details the design rationale, construction methodologies, and benefits of this project, providing a comprehensive case study for similar infrastructure enhancement initiatives.