Singapore awards 35km cable tunnels Sep 2012
Peter Kenyon, TunnelTalk
- Contracts totalling US$1.25 billion are awarded for delivery of 35km of deep-level high voltage power transmission cable tunnels in Singapore.
- Singapore Power announced Monday (September 17, 2012) six contracts for construction of two intersecting tunnels, 14 utility buildings and associated access shafts and adits, and four temporary TBM launch shafts.
Fig 1. 18.5km north-south alignment and 16.5km east-west alignments
- A mixture of up to 10 hard rock TBMs and EPBMs are expected to complete the tunnels in order to keep drive lengths, where possible, to within a single type of geological formation, although mixed ground drives are unavoidable especially along the challenging east-west alignment.
The four companies and JV that will complete the project in six lots are:
• Hyundai Engineering and Construction (South Korea), which confirmed in a press statement a bid price of US$250.2 million.
• Nishimatsu Construction (Japan)/ KTC Civil Engineering and Construction (Singapore) joint venture
• Obayashi Corporation (Japan)
• Samsung C&T Corporation (South Korea) with a bid claimed at US$205.5 million by the International Association of Contractors of Korea (ICAK)
• SK Engineering and Construction (South Korea), for two lots with a bid claimed at US$464.6 million by ICAK.
* Temporary TBM launch shaft location
** Design consultant Hatch Mott MacDonald
*** Design consultant WorleyParsons/ AECOM
- The Jurong Formation has been identified as a variable rock of interbedded sandstones, siltstones and mudstones. The bedrock is expected to be reasonably good for tunnelling, although rapidly varying rock strengths are likely. The most important unit of the Kallang Formation is the Marine Clay, with a maximum thickness of 35m, although 10-15m is more common. The clay is soft to very soft and will require closed face EPBMs.
- Mott MacDonald has been actively involved in feasibility studies for deep level TBM bored cable tunnels in Singapore since the early 2000s, and designed the twin running 3.5m i.d. 1.7km-long Senoko-Gambas alignment on the north of the island, which connects Senoko power station to Gambas Avenue. That project, completed in 2005 by a JV of Obayashi (Japan) and McConnell Dowell (Australia), used a Robbins gripper double shield TBM.
- The drives had been expected to be through extremely hard granite, but the challenging ground conditions that had been anticipated were even more extreme than expected with high water inflows and flowing ground hindering progress of the first 200m of the first drive. Conditions did improve, and with modifications the JV was able to successfully complete both tunnels in January 2005.
- The Senoko-Gambas cable tunnel will connect with the latest north-south tunnel at Gambas, thereby extending the transmission of high voltage electricity from Senoko power station to the south, east and west of the island.
Robbins double shield TBM completed a twin running cable tunnel between Senoko and Gambas, in 2005
Two extremes in one for Singapore's DTSS - TunnelTalk, March 2005
The good, bad and mixed on Singapore's DTSS - TunnelTalk, April 2004
First of six Robbins EPBMs set in Singapore - TunnelTalk, September 2012
Tunnel option for Malaysia-Singapore link - TunnelTalk, May 2012
Singapore DTSS in world's top 100 projects - TunnelTalk, July 2012
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