Bridges

The M1 Pacific Motorway extension to Raymond Terrace project is one of the last remaining major upgrades required to complete a free-flowing dual carriageway route between Sydney and Brisbane. The project connects the existing M1 Pacific Motorway at Black Hill and the Pacific Highway at Raymond Terrace. The southern section of the project involves building approximately 10 kilometres of dual carriage motorway improving travel time and road network efficiency for freight and commuters at the key junction of M1 Pacific Motorway, the New England Highway, and the Pacific Highway Tomago intersection. It will provide improved route reliability in relation to congestion reduction, flood immunity and high demand holiday peak travel.

As part of the project, eight new bridge structures are required. This paper summarises the bridges and presents the main considerations for the design and construction of the bridges. The 2.55- kilometre-long viaduct over the Hunter River and the Bridge over Old Punt Road are presented in separate papers.

Two bridges at Tarro Interchange, which presented design challenges arising from complex alignment, vertical clearances, and urban design integration are presented in detail. The final design solution for these bridges included adopting precast Super-T girders made continuous and integral at the piers to address the high skews and vertical clearance. The key design aspects and construction methodology adopted, including post-tensioning the girders for continuity, will be presented. Details about the other bridge designs and the design development for the solutions, including the design optimisation process used to achieve material reductions and improved sustainability and constructability, and unique reinforced soil wall integration are presented. A series of recommendations from the design and construction process for the bridgeworks will be presented, offering valuable insights for future projects.

At the time of writing, the design is complete and construction is ongoing.