Project Profile: Sydney Metro City & Southwest

The Sydney Metro City & Southwest project is a landmark rapid transit development extending Australia’s first fully automated metro rail system through Sydney’s central business district and beyond. This profile details the engineering specifications, construction methodologies, and strategic impact of this transformative infrastructure. The project leverages advanced tunneling and station construction techniques to increase public transport capacity by up to 60% during peak hours.

Technical Specifications

The core of the project is a 15.5 km twin-bore tunnel connecting the existing Metro Northwest line at Chatswood to Sydenham. Construction required five highly specialized Tunnel Boring Machines (TBMs). Notably, a custom-built dual-mode TBM was deployed for the critical under-harbour crossing, capable of operating in both earth pressure balance (EPB) mode for solid sandstone and slurry mode for softer clays and sediments. The project’s fully automated operations are managed by a Communications-Based Train Control (CBTC) signaling system, enabling high-frequency, driverless services.

Station construction methodologies were adapted to the dense urban environment. Mined caverns were excavated for deep stations like Martin Place and Pitt Street, while the cut-and-cover trench method was used for shallower stations such as Barangaroo and Waterloo. The second phase of the project involves the extensive conversion of the 13.5 km Sydenham to Bankstown line from a legacy heavy rail corridor to modern metro standards, requiring the upgrade of 11 existing stations with features like platform screen doors, level access, and improved accessibility.

Key Takeaways

• Enhanced Network Capacity: The project provides a generational boost to Sydney’s rail capacity, enabling the movement of an additional 100,000 passengers per hour and significantly alleviating congestion on the existing T1 Western and T3 Bankstown lines.
• Advanced Engineering Benchmark: The successful use of a dual-mode TBM to navigate the complex geology beneath Sydney Harbour sets a new technological standard for underwater urban tunneling in challenging mixed-ground conditions.
• Strategic Urban Integration: By combining greenfield tunnel construction with the brownfield conversion of an existing rail line, the project demonstrates an efficient model for expanding rapid transit networks within established urban footprints, enhancing connectivity between major residential, commercial, and transport hubs.

Frequently Asked Questions (FAQ)

When will the Sydney Metro City & Southwest open?

The first stage of the Sydney Metro City & Southwest line, from Chatswood to Sydenham under the CBD, opened to passengers in August 2024. The final stage, which involves the comprehensive upgrade of the Sydenham to Bankstown line to metro standards, is scheduled for completion in the following years.

Who is building the Sydney Metro tunnels?

The primary tunneling contract for the new tunnels between Chatswood and Sydenham was awarded to a joint venture comprising three leading construction firms: John Holland, CPB Contractors, and the international underground specialist Ghella. This consortium managed the complex task of boring beneath Sydney’s CBD and harbour.