Sydney is set to welcome two of the world’s largest tunnelling machines, currently being prepared in China, for the construction of its second harbour road tunnel, known as the Western Harbour Tunnel. This ambitious project is significantly larger than previous metro works, with its scale necessitating the use of these massive machines, which measure 102 metres in length, 16 metres in width, and weigh approximately 4.5 tonnes.
The machines are specifically designed to excavate through 1.5 kilometres of Sydney sandstone, situated 50 metres beneath the harbour. Once operational, they will create a tunnel spacious enough to accommodate three lanes of traffic, connecting the Birchgrove and Waverton areas.
NSW Roads Minister Jenny Aitchison highlighted the project’s magnitude by noting that the required tunnelling is equivalent to constructing three Sydney Metro tunnels. The advanced technology of these machines will enable them not only to excavate but also to line the tunnels as they progress, a significant improvement over techniques used in past projects. According to Camilla Drover, Deputy Secretary of Infrastructure Projects and Engineering for Transport for NSW, each machine will install ten concrete segments to form a complete ring, amounting to 13,000 concrete slabs throughout the process.
The machines are expected to arrive at Glebe Island in the coming months, afterward undergoing a reassembly period in their launch chambers underground. The excavation work will be non-stop, running 24 hours a day with 40 workers on shifts at all times.
Completion of the tunnelling project is anticipated to take about a year, with the final touches expected to wrap up by 2028. Aitchison emphasised that this new tunnel will not only help to reduce travel times but will significantly alleviate traffic congestion in the area, ultimately enhancing the daily commute for many Sydney residents.