First Parramatta milestone achieved

1 December 2003

The first of four TBM breakthroughs has been achieved on Sydney's 13km long, twin-tube Parramatta Rail Link. The event marks an early milestone on one of Australia's largest infrastructure projects. On 21 November, the Thiess/Hochtief JV drove the first of the two 7.2m diameter Robbins machines, that are boring the running tunnels, into the Macquarie Park Station cavern after a 900m drive from the project's central M2 work site.

The 13km alignment has been split into two 6.5km long drives, one currently under construction east to Epping, and the other west to Chatwood, both from a launch shaft at the M2 site. TBM 1 began boring in September through Sydney's Hawksbury Sandstone and after a slow start, requiring modifications to the cutterhead's muck buckets, made good progress. TBM 2 was modified in the same way and launched 3-4 weeks later and good progress has been reported from the start. TBM 2 is expected to break into the cavern in the middle of this month. The project also includes the construction of three new stations by roadheader.

Generally the competent sandstone requires little support, ranging from spot bolting to rare frequent bolting depending on rock class. Meshing of the crown is being carried out primarily from a safety standpoint. Following excavation, the invert is being cast almost immediately behind the machine.

Upon reaching Epping, scheduled for July '04, the TBMs will be brought back to the start shaft, turned and launched to Chatswood. Boring is anticipated to begin in September '04.

The US$629M rail link is the largest publicly funded infrastructure project in New South Wales and is being developed and sponsored by the NSW government. Completion is scheduled for mid 2008.