Bridges

The Dynon Road Bridge over Moonee Ponds Creek is a 12-span, 61 metre long cast in-situ concrete flat-slab bridge constructed in 1941. This art-deco style bridge is heavily trafficked and an important link between Melbourneís western suburbs and the CBD; the bridge and associated route also forms part of a designated and crucial heavy vehicle network route. Additionally, the bridge is located within the project site for the West Gate Tunnel Project, which will continue to 2025 and is part of its heavy haul route.

A Level 3 inspection, structural analysis and geotechnical investigation identified a number of structural defects, some of which were serious. The structure was found to be deficient for HML vehicle loading due to deck capacity shortfalls together with excessive pier movement and rotation which had resulted in reduced seating area and increased eccentricity loading on columns. In addition, concrete remediation was needed to the deck slab and substructure to the 80-year-old bridge to address condition state 3 and 4 defects in accordance with the VicRoads Road Structures Inspection Manual.

To address the matter of bridge structural capacity, strengthening of the bridge for 0.75SM1600 and HML loading was determined and undertaken for 2 primary issues:

1. Slab flexural strengthening using Near Surface Mounted (NSM) Carbon Fibre Reinforced Polymer (CFRP) was extensively implemented above deck and soffit; and
2. Column eccentricity strengthening by concrete infilling treatment (corbelling) extending the deck down-stand nib above the columns to restore a non-eccentric load path for live loads.

The Dynon Road bridge strengthening project involved significant design and construction challenges including development of feasible and cost-effective strengthening design solutions and construction methodologies for the CFRP installation and concrete remediation, all against a requirement of needing the bridge to remain open to traffic at all times during construction.