Rail Underbridge Replacement

Project Summary:

This underbridge project replaced the existing 45.72 metre long, 5 span steel girder structure with a new three span concrete structure on the same alignment. The new abutments are supported by piled foundations, rock scour protection at the piers, abutments, and upper creek banks. A new steel walkway was also installed as part of the new bridge, for use by rail personnel. Utilities that ran along the existing bridge were relocated to under the new steel walkway.

Project Scope:

● Non-possession works:

• Mobilisation, site establishment and maintenance of site.
• Project Management of the works.
• Construction of 12 1200dia bored piles subject to agreement of a safe methodology for piling.
• All temporary works required to facilitate substructure construction.
• Construction of substructure abutment 1 and 2, including wingwalls, piers 1 and 2 and headstocks.
• Supply and storage of all precast concrete elements.
• Supply and storage of all steel walkway, handrail and GST components.
• All other earthworks required including scour protection and embankment shaping.

● Possession works:

• Planning and project management of the works.
• Disconnection of signalling.
• Track removal and replacement to facilitate demolition and replacement of structure.
• Demolition and disposal of exisitng structure.
• Installation of all precast concrete elements.
• Installation of all steel walkway, handrail and GST components.
• Reinstatement of signalling infrastructure on new bridge.
• Abutment 1 and 2 reconditioning.

Key Challenges:

• The project is located in a concentrated flow area, minor rain events could trigger rapid flood water to rise and overtop the working platforms. During the project, seven flood events occurred leading to the development of a Trigger Action Response Plan to mitigate flood damage to the project. Additional strategies included a 450 tonne crawler crane used for possession activities, armouring and redesign of working platforms and accelerated programs during construction stages at higher risk of flood damage.
• This area has constant rail traffic due to the coal trains requiring additional banker engines to climb the Great Dividing Range. Daracon’s internal Protection Officers worked to maintain safe methods of working adjacent to live running rail traffic to complete all substructure works.

Key Success Factors:

• Delivered construction in line with contract program despite numerous flood events.
• Demonstrated commitment to ongoing high standards of safety, quality and environmental performance.
• Executed final commisioning in a rail possession environment in a well planned, highly professional and safe manner.

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