Bridges

The M80 Ring Road Upgrade Project – Sunshine Avenue to Calder Freeway consists of twin 120 m long bridge structures over the former Sunshine industrial waste land fill. The existing structures consist of a cast insitu post tensioned slab, supported on driven piles that are founded at the base of the land fill. The strengthening and widening works are being undertaken by a Design Joint Venture between Arup, Flint & Neill and SMEC, and constructed by Fulton Hogan. The aim of the project is to provide an additional two lanes of traffic in each direction by joining the two existing structures with a similar structural form, namely a cast insitu post tensioned slab supported in driven piles.

The strengthening and widening of the structure over a former land fill presents unique challenges when considered the design and construction technique. In particular, the substructure design and construction had to consider the suitability of the founding material at their base, lateral support provided by the land fill material, and sufficient redundancy in the design should obstructions be encountered. Furthermore environmental considerations were necessary including gas emissions and leachate at the base of the land fill needed to be considered as part of the construction methodology.

The new superstructure has been designed to eliminate the need for strengthening of the existing structure as access under the existing bridge is limited. In addition, the new structure is required to be connected to the existing bridge, which requires carefully design and construction to ensure the insitu stitch pour is formed adequately. Testing of the existing bridge vibration under a variety of traffic conditions will be undertaken such that a vibration from traffic during the stitch pour is limited to satisfactory levels.