The tunnel under the Thames

Engineers are starting work on National Grid Gas Distribution’s biggest civil engineering project – a 330m long tunnel under the River Thames. A critical part of National Grid’s vital work to futureproof London’s gas infrastructure for the 21st century the project involves three of London’s most famous locations: the Royal Hospital Chelsea, Battersea Park and the River Thames.

Engineers are preparing to sink a 30m deep shaft at each of the land locations ahead of digging the 330m long tunnel using a micro tunnel boring machine (TBM), which will be remotely operated from above ground.

Getting to this stage has been a Herculean effort for the project team who have liaised with 15 different organisations and secured almost 20 different permissions before getting the green light. The team have also been working closely with Thames Tideway regarding their nearby Chelsea Foreshore works, to ensure both projects can proceed together harmoniously.

Major events at the Royal Hospital Chelsea, most notably the Chelsea Flower Show and arts fair Masterpiece, have also had to be factored into the project timetable.

The first shaft, which will have a diameter of 7.5m, will be sunk in the grounds of the Royal Hospital Chelsea between January and March 2017. The site will then be cleared to avoid any disruption to the events over the summer. Work will then shift to Battersea Park where the second shaft – with a diameter of 6m – will be sunk between April and August 2017.

Tunnelling will start after the shafts have been completed and should be finished in 2018 after which the new intermediate pressure gas pipe will be installed.