| Gautrain rock arrives for duty |
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| Written by Lucille Davie | |
| Friday, 14 December 2007 | |
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The massive tunnel boring machine, christened Imbokodo in keeping with tradition, has stepped up for its Gautrain mission at the Rosebank site. 
Gauteng premier Mbhazima Shilowa cuts the ribbon at the naming of the TBM
THE rock has arrived in Rosebank, and will begin work in January. Named "Imbokodo", meaning rock, the Gautrain tunnel boring machine (TBM) has been put in place to start boring a 3km tunnel towards Park Station for the rapid rail link. At a naming ceremony alongside the R300-million machine, Gauteng premier Mbhazima Shilowa cut the ribbon and the crowd watched high above the open tunnel as a bottle of champagne smashed against the side of the huge 885-ton, 160m long machine. "Today marks the start of a count down towards the completion of the construction of the Gautrain rail link," said Shilowa. The name is taken from the expression "Wathinta abafazi wathinta imbokodo", meaning "If you strike a woman, you strike a rock". It was sung by the women who led the march to the Union Buildings in 1956, protesting against having to carry passes. It is traditional to name these machines after women as a sign of good luck for the project. It is also traditional to name the TBM before work starts. According to a Gautrain statement, the chosen name is appropriate "to honour our continent's mothers, sisters and grandmothers. Ordinary women that make things happen – also on Gautrain." Milestones 
Bombela officials pose alongside the huge TBM, giving perspective on its size
Shilowa recalled other milestones along the Gautrain journey: the final signing of the agreement with all parties; the final close with the banks; the beginning of construction in Marlboro in September 2006; and, today, the start of the tunnel boring with the TBM. "We began together, but the Gautrain will outlive me in Gauteng," he said, smiling broadly. Other TBMs used around the world have been given names like Emerald Mole, Envira, Delilah and Aurora. The Imbokodo was designed by German manufacturer Herrenknecht, a specialist in mechanical tunnelling equipment that has been in the field for over 30 years. Its machines are working on 100 traffic tunnelling construction sites around the world. "Imbokodo therefore symbolises a country's heritage of will power in its drive to overcome obstacles," said Jack van der Merwe, the chief executive of the Gautrain Management Agency. "Those of us who believe in gender equality and women's emancipation will not fail or falter in our efforts to ensure women continue to play a central role in the development of our province and country," Shilowa added.
Naming ceremony The TBM is necessary because of the presence of some 300 to 400 metres of hard granite rock spurs in the 3km section between Rosebank and Park Station in Braamfontein. The machine was designed and manufactured in Germany, shipped to Durban and transported to Joburg by road, and then assembled in November. The section that is now in place at the entrance to the tunnel in Rosebank is only half of the full machine, still to be put in place. "The benefits of using a TBM for tunnelling are recognised worldwide. These giant machines are usually designed to bore tunnels in specific areas and to cope with site-specific ground conditions," says a Gautrain statement. "A computerised guidance monitoring system is used to steer the machine accurately underground while the machine and tunnel lining resist the soil pressures during and after the tunnel construction. This means that a TBM is an environmentally sound method of tunnelling, especially in built-up areas." TBM operation 
Balloons rise as the Imbokodo is named
The machine, referred to affectionately by officials as the "big girl", is fronted by a cutting wheel 6,8 metres in diameter, the means by which the earth is excavated. Behind the wheel is a chamber where the excavated material accumulates before it is fed backwards via a conveyer belt, to be dumped into tipper trucks. The wheel bores into the earth at 1,5 metres at a time, while the tunnel is lined with concrete rings at the rear of the machine. The tunnel structure is thus completed, section by section, as the TBM slowly moves along "like a giant earthworm". It is driven by a pilot who sits in a control cabin surrounded by banks of computer screens, guided by the target he is working towards. It will excavate for about 14 months, after which it will be dismantled, with a possibility of being used for other projects elsewhere in the world. The machine will be operated 24 hours a day, seven days a week. The advantages of using a TBM are that there will be almost no noise or vibrations, which are being experienced in Sandton, where underground explosions occur at the Mushroom Farm site; and other construction above ground can continue unhindered. The disadvantage is that operations will ground to a halt with power outages. Durban harbour's undersea tunnel was built using a refurbished 4,4m TBM. Six TBMs were used to excavate three tunnels in the Lesotho Highlands Water Project. These TBMs were created for particularly hard rock conditions and would not have been suitable for Rosebank. The 80km rail link will travel between the Joburg CBD and OR Tambo International Airport, with a line going to Tshwane. Work is continuing at 45 sites across Joburg and Tshwane, and it is expected that the line from the centre of town to the airport will be completed in 2010, while the Tshwane line will be completed in 2011. So far R7-billion of the R25-billion budget for the Gautrain has been spent. Shilowa said that the Gautrain had been successful in convincing 37 construction professionals who left the country to work in the United Kingdom, to return to South Africa. Some R440-million has been injected into the economy so far this year through the purchase of South African materials and equipment. Small, medium and macro enterprises have gained R70-million by providing goods and services required on the projects, he added. More than 5 400 direct jobs have been created. More information can be obtained from the Gautrain website or from the Gautrain toll free number 0800 Gautrain (0800 428 87246).
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