EIC Case study: West Gate Tunnel – Cable-Stayed Bridge
The structures team at EIC Activities was recently engaged to provide the construction methodology, bridge erection manual and associated temporary works required to build a pedestrian cable-stayed bridge on the West Gate Tunnel project.
The new pedestrian bridge will provide a grade separated crossing from the north side of Footscray Road to the southern east side of Waterfront Way.
About the project
CIMIC Group company CPB Contractors was selected by Transurban and the State Government of Victoria as the preferred contractor for the West Gate Tunnel project, in a 50:50 joint venture with John Holland.
The West Gate Tunnel project, one of Victoria’s largest ever urban road projects, will deliver a vital alternative to the West Gate Bridge, provide quicker and safer journeys, and remove thousands of trucks from residential streets.
Scope of EIC’s involvement
The EIC team’s involvement included:
- Technical support of the development and optimisation of construction methodology
- Detailed construction staging (not covered in the permanent works design i.e. the bridge erection manual)
- Detailed design of all associated temporary works
- 3D and 4D modelling of the bridge and associated temporary works with clash detection throughout the entire construction phases.
The team was also engaged to provide engineering support during construction.
The bridge erection manual covers all stages from lifting pylons onto the substructure to completion of the bridge construction.
This details the construction sequence, expected deflections and stay force adjustments based on staged analysis of the cable-stayed bridge.
The complexity of the cable-stayed bridge construction methodology and temporary works included:
- Asymmetrical one-line semi-fan configuration cable stay arrangement
- Reverse horizontal curve with vertical crest curve alignment
- The nature of the highly sensitive steel box deck structure, where any variation in the loadings and self-weight significantly affects the deck geometry and the global deflections of the girder and the pylon
- Required geometry adjustment with detailed step-by-step construction sequence to align the incoming girder to the previously erected girder using temporary adjustment structures
- Soft ground foundations and associated large settlements
- Temporary supports used to support girder erection prior to splicing, connection to pylon and cable stressing
- Temporary structures, crane lifting operations and locations needed to take into consideration of the existing above and underground services and live traffic operations
- A short closure of the arterial Footscray Road required for the erection of the central spliced girder over Footscray Road.
A team effort
EIC staff involved on the project included:
Colin Edmonds, EIC’s Technical Director for structures, led the construction engineering of the bridge erection manual.
Matt Hennessy carried out the staged construction analysis and capacity assessment of the bridge. Matt was also the package lead for service impact assessment and splice adjustment structures.
Project Manager of EIC’s engagement with Bridge 91, Phoebe Tay, managed the deliverables of all construction staging and temporary works packages. She was also responsible for the verification of the bridge erection manual.
Jeff Roper, who is responsible for the temporary support and laydown support packages has been working closely with the project team and supplier to determine a cost-efficient solution for temporary towers, working together structural requirements of the towers with access to facilitate construction works.
John Potts who is EIC’s Heavy Lift Specialist provided lifting concepts and rigging arrangements for the girder and pylon installation working closely with the project team to manage the site constraints. John reduced cost impacts by removing several crane pads and the need for self-propelled modular transporters.
Jawad Zeerak leading the Geotechnical portion of EIC’s engagement has assessed the impact of the temporary works and construction engineering on the existing ground and provided several crane pad designs for the construction of the bridge.
3D Modelling of the bridge was undertaken by Leighton Asia’s 1DCS group. This assisted planning with lift studies and clash detections.