The first two tunnel boring machines (TBM) have been launched for the Sydney Metro West line in New South Wales, Australia. The TBMs will bore tunnels for a 24 km (15 mile) section.

The Acciona and Ferrovial joint venture (JV) has begun major tunneling works on the underground railway that will connect Greater Parramatta and the Sydney central business district (CBD). The JV was awarded the A$1.96 billion central tunneling contract on the scheme in July 2021.

Ground Engineering reported that the Herrenknecht TBMs arrived at the Bays Station site in October of last year.

The first TBM, dubbed Daphne, has already dug 150 m (492 ft) of its 11 km (7 mile) drive from the Bays to the Sydney Olympic Park, while TBM Beatrice is 45 m (147 ft) into its journey on the parallel tunnel. They are expected to excavate an average of 200 m/w (656 ft/week) and to finish tunneling in late 2024.

The two TBMs, which are the first ones in the ground for the project, include refurbished parts from the TBMs used on the Sydney Metro City & Southwest project. The cutterheads, front shields and gripper shields were originally used for the TBMs that dug the metro tunnels from Chatswood to Blues Point.

Work on cross passages and crossover caverns will also progress, while the TBMs continue their excavation.

The project's western tunnelling contract, covering 9 km (5.6 miles) of rail tunnels between Sydney Olympic Park and Westmead, was awarded to a Gamuda and Laing O’Rourke Australia JV in March 2022.

A John Holland, CPB Contractors and Ghella JV won the 3.5 km eastern tunnelling contract between the Bays and Hunter Street in Sydney’s CBD in November of last year.

Meanwhile two out of a total of three roadheaders have started digging tunnels that will connect the Sydney Metro West line to a new stabling and maintenance facility at Clyde.

The 120 t, 4.8 m (15.7 ft) high and 4.5 m (14.7 ft) wide machines were lowered into a temporary access shaft at Clyde, which is approximately 28 m (92 ft) below the surface. A 750 t mobile crane then carefully lowered each roadheader into the shaft in pieces, with the heaviest load weighing just over 92 t. It then took two days to assemble each machine.

The final roadheader will soon be assembled to help excavate the tunnels and two junction caverns that will allow trains to move from the underground railway tunnels to be stabled and undergo routine maintenance as required.

It will take around 13 months for the roadheaders to excavate the tunnels and junction caverns.

Earlier this year, New South Wales premier Chris Minns said that the full Sydney Metro programme needed to undergo a major review due to cost overruns and delays. The final report is expected by the end of this year.

The Guardian recently reported that the overall scheme was already A$21 billion over budget, and Sydney Metro West had gone over its initial estimates by A$12 billion to A$25.32 billion.

The Sydney Metro is Australia’s biggest public transport project and includes three schemes. In addition to Sydney Metro West, these are City & Southwest and Western Sydney Airport. As a result of the project, by end of 2030, Sydney is expected to have 113 km of new metro rail.