Bridge 1 at Rapahoe and Cobden Rail Bridge

We undertook a comprehensive assessment of the original timber truss railway bridge - originally constructed between 1896-1899  - to determine the remaining service life, identify remedial options and evaluate options for retaining the original bridge.

The decision was made to replace the timber bridge with a new bridge which offerred an opportunity to improve rail operations at the same time. During construction of the new bridge train operations were to remain uninterrupted, necessitating remedial work and monitoring of the old bridge.

The new 290 m long bridge incorporated 27.5 m span precast post-tensioned beam components. In collaboration with the contractor, to best suit their construction methodology, we reanalysed and re-detailed the superstructure to allow precast post-tensioned L shaped components to form the major components of the final U shaped bridge superstructure.

The operational changeover to the new bridge was achieved in June 2006. The entire Bridge 1 Rapahoe renewal project was completed within programme and budget. In 2008, the project received an ACENZ Award of Merit in recognition as an outstanding project.