Four Road Headers Now Work on Cross City Tunnel in SydneyFour roadheaders are now tunnelling underneath Sydney to build the Cross City Tunnel (CCT). Since the first machine started work on 19th May, over 500 m of tunnelling have already been completed. The first two roadheaders were delivered onto the sites at ground level and then burrowed underground.However, the third roadheader to arrive on site had a far more difficult entry method than the first two machines, which used the former Bourke Street entry ramp to the Eastern Distributor (ED). A vertical shaft, equivalent to the height of a 12 storey building, was excavated inside the noise reducing shed at the corner of Bourke and William Streets, Woolloomooloo. On 7th August, the third machine was then lowered in sections down the 42 m shaft and reassembled at the bottom. This was an extremely challenging and innovative task, taking over seven hours to complete and using a giant 400 tonne capacity mobile crane. Support systems such as power and ventilation were connected to allow it to start working from 11th August.With three machines now working beneath William Street, a fourth machine has been brought on site, this time at Sir John Young Crescent, to cut the Cross City tunnel exit that links traffic from the eastern suburbs.Machine 1 is cutting the 650 m-long ramp which joins the eastbound CCT to the southbound Eastern Distributor. It is currently cutting westbound beneath William Street near the Australian Museum. Machine 2 began working on 2nd June, excavating the link from the Eastern Distributor to the westbound CCT. This machine is now cutting beneath William Street in the vicinity of Riley Street. Machine 3 will initially cut slightly southbound until it is aligned with the main westbound tunnel. It will then turn to the east and start excavating the main tunnel towards Rushcutters Bay. Machine 4 will initially deepen the excavated trench it has been placed in before it starts cutting a tunnel beneath Riley Street. This will create an exit in Sir John Young Crescent for CCT traffic travelling from the east to Macquarie Street or the Harbour Crossings.Seven road headers are to be used on the project. The maker of the machines is Mitsui of Japan. There are five S300, one S200 and one of another type. None is new. Three are from the M5 east motorway for which they were bought new. The contractors Baulderstone Hornibrook and its parent company Bilfinger Berger refurbished them. Two were purchased second-hand from the northside storage tunnel project. One was purchased from Brisbane-based company Eroc and the last one was shipped from Germany. The cost is approximately A$3 million per machine. Each machine weighs 100 tonnes and is powered by a 1,000 volt electric system.The road headers and their specialist crews will each average six lineal metres of excavation through Sydney sandstone each day, working across a face 8.6 m-wide and 7.8 m-high and removing about 400 cubic metres daily. 680,000 cubic metres of spoil will be excavated. Tunnelling takes place 24 hours a day. A total of 8.5 km of tunnels needs to be excavated to form the 2.1 km Cross City Tunnel. Click au/20. Visit www.crosscitymotorway.com.au, www.bh.com.au and www.bilfinger.de 36/03.