The giant machines digging the main Thames Tideway tunnel have now bored over 13km of the 25km total length.
The tunnel now stretches as far west as Fulham and, eastwards, it has reached Blackfriars in the City of London – passing under 13 bridges including Albert Bridge, Westminster Bridge and Waterloo Bridge.
So far, the tunnels have been constructed using four tunnel boring machines.
Two more tunnelling machines are due to start working in east London this year, creating the eastern section of the main tunnel from Bermondsey to Newham, as well as a slightly smaller 4km connection tunnel in Greenwich.
The project is looking to develop innovative ways of works and has introduced pre-shift work-outs to help prevent musculoskeletal disorders at Thames Tideway.
Andy Mitchell, Tideway CEO, said: “After more than three years of exceptional work by our teams across London, we’ve reached the halfway mark on the super sewer.
“There’s still a way to go but reaching this point on schedule is testament to the success of the team, who have achieved a huge number of engineering feats – including tunnelling under the river through a variety of ground conditions, building new pieces of land in the Thames to work in and digging giant shafts up to 50m deep below London.
“Once complete, not only will we have a cleaner river but there will be seven new areas of public space created along the Thames, transforming the embankment and creating new areas for Londoners and visitors to reconnect with the river.”
As well as the main tunnel, a 1km connection tunnel is also currently under construction in Wandsworth.
Tunnelling is due to complete in 2022, allowing up to two years of commissioning for a March 2024 opening.