Herrenknecht Tunnelling for Sewage Superhighway Completed

A milestone for the epoch-making “Deep Tunnel Sewerage System” (DTSS) project in Singapore was reached: the five contractors have completed tunnelling works for the second construction phase of the gigantic sewer pipe system.

The final breakthrough took place in July 2023. A total of 19 Herrenknecht tunnel boring machines (TBMs) had excavated and lined some 49 km of tunnel since 2019. In addition, a Herrenknecht Vertical Shaft Sinking Machine (VSM) was used. Among the challenges for machines and miners was the city state’s complex geology. The Jurong Formation, for example, consists of sandstone, siltstone, mudstone, limestone, dolomite and some conglomerate, which are extremely folded due to tectonic plate movements. As a result, diverse rock types with different weathering grades often alternate along a tunnel alignment and even in the cross section of a tunnel. In close cooperation with the customers, the design of the TBM was therefore adapted to the complex geological conditions. Herrenknecht has been using its tunnelling technology for a quarter of a century in Singapore, with TBMs being used again and again at numerous jobsites for subway and electricity tunnels.

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