Transport for London briefing:
Tunnelling starts at the shafts
If you have passed through the Kennington area in the past three months you may have noticed large green structures at Kennington Park and Green. These are temporary acoustic enclosures, designed to reduce noise, dust and light pollution from the tunnelling works and will be in place until early 2018. They house a large gantry crane, silos for mixing the concrete used to build the tunnels and space for the excavated material to be stored overnight. This is particularly important as the project moves into 24/7 working and will reduce the number of lorry movements required, especially at night.
Inside the enclosures the teams have been digging out the ventilation shafts and at the end of August we reached the bottom. The shafts are 25m deep, and 18,000 tonnes of spoil was removed during the works and taken to the NLE Battersea Power Station site, where it was loaded onto barges via the jetty.
First to be dug out are the ‘tunnel eyes.’ These are short sections which prepare for the tunnels to be constructed between the shafts and Kennington station. Another small section of tunnel is also prepared at the back of the shaft, ready to receive the tunnel boring machines from Battersea Power Station in late 2017.
This stage signals the beginning of tunnelling works and is an exciting milestone for the project to reach. The tunnels are dug by small machinery and are expected to take around three months to build. The works will culminate with the building of a link to the existing Northern line at the Kennington Loop, called a step plate junction. This is a technical and very complex piece of work involving precise hand-mining and very little machinery. The step plate junctions will take about seven months to build and will provide an exciting new experience for the project team as we interface with the existing railway.
We are building two permanent shafts at Kennington Park and Kennington Green to provide ventilation, cooling and emergency access to the tunnels.
The majority of works at the Kennington sites now take place underground. Works on the surface may include the fabrication of steelwork and the maintenance of machinery and vehicles to support the tunnelling operation. Traffic management measures remain in place and we thank you for your patience during this time. The pedestrian crossing to the south of Kennington Green is also in the process of being constructed and is expected to be in operation at the end of September.
Work over the next three months at both Kennington sites will include:
- Continuing tunnelling works towards the Kennington Loop
- Repairing the road surface on Kennington Road to the north of Kennington Green
We are building a new Underground station at Nine Elms near Pascal Street and Wandsworth Road.
Piling works continue, with more than 330 piles completed (more than 95 per cent). This includes the construction of larger and deeper steel beams (plunge columns) that will support the future over-site development. Large beams have also been placed using the gantry crane to support the excavation of the station box and to prevent ground movement. These concrete beams are reinforced with steel and ‘stitched’ together to eventually form the roof of the station box. The first concrete floor slab has also been constructed, which will form the floor of the future station ticket hall. Capping beam construction continues to strengthen the station box and repair works continue to be carried out to Pascal Street.
Works over the next three months include:
- Completing the piling works
- Completing the capping beam works
- Starting to excavate the station box and placing support beams
Battersea Power Station
We are building a new Underground station next to Battersea Park Road and the Battersea Power Station development. It will be called ‘Battersea Power Station’.
Excavation continues in the crossover box in preparation for the launch of the tunnel boring machines. Temporary steel beams continue to be installed to support the excavation. Piling and diaphragm wall works continue at the west end of the site in the station box, with more than 55 piles completed (35 per cent). Excavated material continues to be removed from the site via a conveyor to the barges at the Battersea jetty and additionally, excavated material from the Nine Elms works is being taken to the Battersea Power Station site to be removed in the same way. In total, 180,000 tonnes of spoil has been removed (184 barges), saving 270 tonnes of CO2 emissions, equivalent to 630 standard road vehicle emissions in a year.
Works over the next three months include:
- Continuing with diaphragm wall works in the station box
- Building the capping beam to strengthen the crossover box
- Continuing barge movements
- Continuing excavating the crossover box to the base slab
- Arrival of the tunnel boring machines
You said, we did…
With work continuing on all sites we have received a number of enquiries and comments. Some of the topics include:
- Noise and vibration – we have liaised closely with affected residents and are monitoring buildings
- Working hours – we are advising residents and the local authority in advance if extended working hours are required due to unforeseen circumstances
- Defect surveys – defect surveys continue and will be carried out no less than four weeks before works start that may affect your property
- Traffic management – we are working closely with TfL Surface Transport and continue to host regular meetings with affected residents
- Splashes from site plant – we are investigating installing a covered walkway close to hoardings where we are piling at Battersea Power Station
Community Liaison Groups
The following Community Liaison Groups meet regularly to provide residents, businesses and councillors with an opportunity to find out more about the Northern Line Extension project:
- Kennington Park and Newington
- Kennington Green
- Nine Elms and Oval
- Core Group – an overall liaison group that considers route-wide issues
All residents are welcome. You can see presentations, minutes and details of upcoming meetings on our website here. .
Transport and Works Act Order decision
Main works start
Tunnel boring machines arrive on site
Testing and commissioning
Extension in operation
Staying in touch
For more information and to register for updates on the scheme, visit tfl.gov.uk/northern-line-extension
There are details on TfL’s Commitments, the planning documents and the Construction Noise and Vibration Mitigation Scheme.
You can also email the project team at email@example.com or call our helpdesk on
0343 222 2424 (Option 1).
We will be running regular ‘drop in’ sessions at all sites. Dates and locations will be on the website, community notice boards and emailed to those who have registered.
Transforming the Northern line
The extension includes 3.2km of two new tunnels connecting to the existing Northern line at Kennington and two new Underground stations at Nine Elms and Battersea Power Station.
It is part of a massive investment programme to transform the Northern line which includes:
- A signalling upgrade – this has already achieved a 20 per cent increase in capacity through central London
- More frequent trains following the signalling upgrade
- Rebuilding Tube stations which are critical to improving capacity and supporting regeneration. They include Tottenham Court Road, Bank, Camden Town and Elephant & Castle