Fionnuala, a 3.4m diameter Lovat TBM has completed a 3km journey between South East London and East London whilst building a £27M cable tunnel for Client UK Power Networks.
UK Power Networks, which owns and operates London’s electricity network, has built the tunnel between South East London and East London in partnership with contractor J Murphy and Sons as part of a wider project. The tunnel adds to the existing network of underground tunnels, which deliver power supplies across London.
Darren Ramsay, from Murphy, said: “I am so proud of the work of our team, spending two years underneath London to help ensure reliable power supplies in the capital, working collaboratively with our client UK Power Networks. Each milestone was successfully negotiated, from the challenges of tunnelling underneath the River Thames, the Jubilee tube line and train tracks running into London Bridge. The final breakthrough in East London will be achieved with minimal disruption to Londoners and the environment. It is testament to the work of our team, successfully achieving break-through despite difficult ground conditions without deviating from the original tunnel line – impressive given the 3km distance, and given that each end of the tunnel was bored nearly two years apart.”
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The 6 piece segmentally lined tunnel is the third and final stage of a three-part tunnelling project to install new 132,000 volt electricity cables along a longer 5.7km route between substations in South East London and the City. The first stage, completed in 2011 with J Murphy and Sons, was a £1.1M 30m long interconnecting tunnel and junction chamber. The second stage was a £14M 2.7km long tunnel between East London and the City, completed with Morgan Sindall in March 2013.
The TBM has progressed at a rate of up to 23m per day at depths of between 22 and 30m through layers of chalk, clay, gravel and sand.
Now the 2.85m i.d tunnel is finished it will be lined with hundreds of brackets to carry 132,000 volt electricity cables, connecting substations between South East London, East London and the City. Work to fit out the new tunnel is due to start in July and last seven months and the new cables are due to go live next summer.
Nirmal Kotecha, director of capital programme and procurement at UK Power Networks, said:
“London’s power needs are increasing all the time and we are constantly investing in new infrastructure to ensure we maintain reliable electricity supplies. This essential project will increase the resilience of electricity supplies for residents and businesses for years to come. By working deep underground with the Murphy specialist team, we were able to avoid digging up roads along the entire route, helping keep the impact of this major project to a minimum.”