Epping to Chatswood - the final touches

This article describes how tunnel boring machines (TBMs) are being used to construct a new, 12.5-kilometer rail line between Chatswood, a business center near Sydney, Australia, and the outlying suburb of Epping. The $679 million project includes twin running tunnels and four underground stations. The article describes in detail how the refurbished 7.2-meter TBMs were used to excavate the tunnels, what type of rock was bored, the design of the tunnel support system, and the sequencing of the work. It also describes the permanent lining of the running tunnels, a circular-formed, un-reinforced concrete, and water control. A number of innovative solutions were devised for the project, which is scheduled to be completed in 2008.