As T&TI goes to press, contractor Kumagai has begun tunnelling through the central business district of Perth in Australia with a 60m long TBM manufactured by Mitsubishi Heavy Industries (MHI).

T&TI has learnt that mechanical difficulties with the conveyor system of the machine delayed the start of tunnelling on the first 470m section of tunnel. The jv was due to start tunnelling on October 5, T&TI was told the machine was finally launched on 25 October.

The EPB machine, dubbed “Sandgroper”, will bore a 6.9m diameter tunnel through sand, clay and gravel along an alignment below the water table. Excavated spoil is transported out of the tunnel by locomotive and then trucked to landfill sites. Lining is by way of bolted precast concrete segments produced by Humes in Perth.

Manufactured in Japan, the machine is the 1649th to be made by MHI. It will be used to bore twin 770m long tunnels between two railway stations as part of the Western Australian Southern Suburbs Railway linking the city to Mandurah, 75km away. The Western Australia Premier Geoff Gallop told local press that creating the twin 770m tunnels would be “one of the most significant engineering tasks ever attempted in Australia”.

The TBM was launched from the north of The Esplanade Station and will drive through the box for William Street station platforms until it eventually reaches a reception pit south of Roe Street. It will then be dismantled and transported back to the launch box at the Esplanade Station for reassembly and boring of the second tube.

The project has recently won the approval of the Western Australian government’s auditor-general for the way it is being managed. In the report it was also noted with praise that responsibility and the majority of the cost risk for the design and construction contract rest with the contractor, a jv of Leighton-Kumagai for the overall scheme. The Public Transport Authority engaged Maunsell as consultant on the scheme that also includes three sections of cut and cover tunnel.

Bored tunnelling is scheduled to continue on a 24 hour day basis until completed. The TBM is expected to advance at 10m per day and complete the construction of both tunnels by December 2006. The consortium won its US$241M contract in February 2004. Despite the problems the contractors are confident that this first section will completed by Christmas. Leighton is confident it will meet the overall completion deadline of December 2007.

The difficulties are the latest to beset the project after a series of industrial problems has delayed the contract by at least four months. Further delays are possible after the Construction, Forestry, Mining & Energy Union of Australia said it would seek an extra US$74 for its members after revelations that electrical workers were paid more than construction union members with the same experience.

Union leader Kevin Reynolds said: “I think if extra money is to be paid to these (electrical) blokes, then it should be paid to all of them. I’m certainly not suggesting that the (electrical) workers shouldn’t get that money – I’m just saying that that money should be paid to all of them. A tradesperson is a tradesperson, and all tradespeople, whether they are carpenters, bricklayers or boilermakers, deserve to be on the same rates of pay.”

Premier Gallop predicted rising fuel prices would see the expanded system attract record patronage. He said: “With petrol prices on the rise, the completion of the Southern Suburbs Railway will offer a faster, cleaner and economical alternative to car travel to residents in the south metropolitan region.”