Tunnelling Journal can reveal Costain is the preferred bidder for National Grid’s three cable tunnels in London totalling 30km of 4m diameter, TBM driven segmentally lined tunnel. The three tunnels, to be built mostly through London Clay, are the 12.5km long Hackney to St John’s Wood tunnel, the 7.4km long Willesden to St John’s Wood tunnel, and the 12.1km long Wimbledon to Kensal Green tunnel.
A spokesperson for National Grid told TJ, “Following a review of the London Tunnels scheme last year, which is standard procedure to ensure we continue to meet our regulatory obligations to be cost effective and efficient, we revalidated our previous tendered work to build a new high voltage electricity cable tunnel between Hackney and Willesden (via Kensal Green) and Kensal Green and Wimbledon. Following this tender process Costain is our preferred bidder and a formal announcement and contract award will be made later in the year.”
“The tender covers the design and build contract for the actual tunnel. This includes the necessary headhouses and ventilation equipment. We plan to have the contract in place by the end of the year with works starting in 2011.”
A fourth cable tunnel, the 7.1km long Hurst to Eltham Tunnel, that was originally planned to be build with the three just awarded has been put on hold.
“Hurst to Eltham has an existing overhead line connection which we are looking refurbish as a medium term strategy, which means we are able to meet our obligations to be cost effective and efficient. A further review will confirm these requirements however, a tunnel is currently planned with construction expected in 2015,” the spokesperson said.
If the fourth tunnel gets the go ahead, National Grid will have in the region of US$930M worth of tunnelling work under construction in London.
More soon
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