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WestConnex (WCX) 3A Project Design and Construction – Sydney (Australia)

by Mathieu Gonzalez (Dragages Hong Kong) and Leo-Paul Calbrix (Bouygues Construction Australia)


24 August 2023


10:30 am



The WestConnex M4-M5 Link Tunnels (WCX Stage 3A) project is a 7.5 km Sydney underground link connecting the WestConnex M4 East Tunnel at Haberfield and the WestConnex New M5 (M8) Tunnel at St Peters Interchange. The project commenced in June 2018 and was completed early 2023. The project comprises 21.6 km of roadheader tunnel excavation, tunnel civil fit out works, surface civil works, Mechanical & Electrical (M&E) installation and Testing & Commissioning (T&C) including integration with M4 and M8 network. To deliver the project on time, to improve the overall logistics, optimise resources and maximise underground productivity & efficiency, a “Tunnel Production Line” (TPL) strategy has been developed from the start of the project. This presentation will present how the TPL has been defined, implemented, monitored and refined during project execution, focusing on the activities from tunnel excavation to internal handover to Tunnel Civil and then to Tunnel M&E and finally to T&C phase.

The presentation will also focus on the design aspect of the project, with detail of the temporary supports, permanent supports and geotechnical designs. Moreover, it will provide details on how some design decisions have been made in order to ease and expedite the construction of the project while improving the coordination and inclusion of the different disciplines’ constraints (tunnel, civil works and M&E).

About the Speaker:

Mathieu Gonzalez is currently the Senior Technical Manager for Dragages HK on the T2 Trunk Tunnel project in Hong Kong. He is a fellow of the Institution of Civil Engineers (ICE), Chartered Engineer and Project Manager Professional (PMP).

He has over 16 years of experience in the construction industry, from design to construction methodology to technical management for main contractor. He has been involved on various projects in France, Spain, Hong Kong and Australia starting by Tunnel Boring Machine (TBM) projects to manage the technical team on major infrastructure tunneling project with multidisciplinary deliverables (tunnel construction to project commissioning) from building, civil works, tunneling works, rail, E&M, T&C, etc.

Leo-Paul Calbrix is a Civil Engineer with over 13 years’ working on construction projects in France, the middle east and Australia. He has a strong background delivering diverse project on both designer’s and contractor’s side. His experience includes Building Design, Underground Structure Design, Design Management for major tunnel infrastructure projects and Project Management. On WestConnex, Leo-Paul was the Design Manager for the underground works and was promoted acting Design Director during the course of the project.

Leo-Paul is currently working for Bouygues Construction Australia as Bid Manager. He has a Master Degree in Civil Engineering and Project Management and holds a Professional Chartership with Engineers Australia (CPEng).

Registration :

Please register by 22 August 2023. Successful applicants will receive webinar details after registration. CPD certificate will be sent to the attendees, who attended more than 80% of the webinar time, within 2 weeks after the webinar.

Book Prize :

The youth professionals under 35 years old are encouraged to submit their reports (max. 500 words) in quality on this event. Please refer to the AGS (HK)’s website “The AGS Book Prize Reports – Assessment Framework” for details before the submission. The successful candidate will be awarded with the Book Prize that comprises of a book "Geology of Site Investigation Boreholes in Hong Kong" that written by Chris Fletcher, and a coupon of HK$500 from Eslite Spectrum (誠品生活) or equivalent. Ther awarded report will further be uploaded to the website of AGS (HK). Please send your report to Mr. Haydn Chan by email:


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Reference materials

Download the presentation slides and other reference materials below.

Snapshots of the Day

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