Costain has announced that it has been awarded the US$318M contract by National Grid for its 33km long, 4m diameter London Cable Replacement Tunnel system in London. TJ revealed Costain to be the preferred bidder in August, for the scheme that will see the contractor build a new high voltage electricity cable tunnel between Hackney and Willesden (via Kensal Green) and Kensal Green and Wimbledon. The TBM driven tunnel runs through mostly London Clay, and will feature a segmental lining. Works will start later this year, with the tunnelling being completed by end of 2014 and with all associated works completed in November 2018.
“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 National Grid spokesperson Told TJ in August.
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.