What does National Grid do?

It is National Grid’s job to connect people to the energy they use. We play a vital role, delivering gas and electricity efficiently, reliably and safely to millions of people across Great Britain. In England and Wales, we own and operate the high voltage electricity transmission network and have day-to-day responsibility for balancing supply and demand across Great Britain. We also have operations in the north-eastern states of the US, and are one of the largest investor-owned energy companies in the world.

Who regulates National Grid?

National Grid is regulated by Ofgem (Office of the Gas and Electricity Markets). Further information about Ofgem is available on its website, www.ofgem.gov.uk.

What is the LPT phase 2 project?

The London Power Tunnels phase 2 project follows the success of our original London Power Tunnels (LPT1) project, a seven-year £1 billion scheme to rewire the Capital. LPT1 involved building 32km of tunnels and two new substations. As part of this second phase, National Grid is building a new network of cable tunnels in South London, 32.5km in length, between Wimbledon and Crayford.

Why do we need these tunnels?

The project is essential to replace existing cables which currently run beneath the road network in order to ensure a continued safe and reliable electricity network. In London, most electricity is transmitted through underground cables. These are traditionally located just beneath the road surface, and work to maintain them is usually carried out in the road. By housing new electricity cables in tunnels deep below the surface, a number of advantages are achieved compared to more traditional methods:

  • Overall disruption to Londoners and road users during construction is significantly reduced as the majority of the works will take place deep beneath the ground
  • Future repair and maintenance can be carried out with minimal disruption to residents, traffic and businesses

What route will the tunnels take?

The three sections we are replacing are:

  • Section 1: Wimbledon to New Cross – Operational by: 2025
  • Section 2: New Cross to Hurst – Operational by: 2026
  • Section 3: Hurst to Crayford – Operational by: 2026

How did you determine the route for the tunnels?

There were a number of key considerations for determining the proposed tunnel routes including:

  • The location of National Grid’s existing substations (start and end points for the new electrical circuits)
  • Environmental impacts, such as avoiding source protection zones for drinking water
  • The need to avoid other underground infrastructure
  • Ventilation and safety requirements (we need to have a shaft every 7km)

Does National Grid have the rights to carry out this work?

We are building the tunnels and shafts under our permitted development rights, which means we do not need planning permission for the entire project. However, there are points along the tunnel route where we need to build new headhouses to cover the shafts. National Grid has secured all necessary planning permissions for construction activity sites which do not fall under our permitted development rights.

When will this work be taking place?

Section 1: Wimbledon to New Cross

Length: 12km

Operational by 2025

 Section 2: New Cross to Hurst

Length: 18km

Operational by: 2026

Section 3: Hurst to Crayford

Length: 2.5km

Operational by: 2026

When will the project be complete?

Construction works will begin in spring 2020 and it will take approximately six years to complete the project.

Who are the contractors for the project?

The contract for the tunnels has been awarded to Hochtief Murphy Joint Venture for the detailed design and build of our tunnel network, which will house the new electricity cables. Further contracts will be awarded for other elements of the project.

How deep are the tunnels going to be?

The depth of the tunnels will range between 12m and 63m. The majority of the tunnels will be around 30m deep (the height of a typical three-storey building).

What are shafts and headhouses?

Shafts and headhouses are required at key points along the route of the tunnels. A tunnel boring machine will travel between these points as it progresses along the route.

Shafts are approximately 15 metres in diameter and between 30 – 40 metres in depth. Shafts are used to lower tunnel boring machines. Once the cables are installed, any shafts which are not required for access or ventilation are backfilled.

A headhouse is a building which covers a shaft. Shafts and headhouses are required for the following reasons:

  • Health and safety – it will be essential to have access points to ensure the safety of our workforce during construction. The shafts will also be used to access the tunnel for maintenance work once the tunnels are built and operational
  • Ventilation – ventilation equipment, in the form of fans, will be required at some sites to cool the cables and regulate the temperature inside the tunnels.

What are your working hours?

Working hours will vary by site, for more information please check our In Your Area pages. 24-hour working will be required while we build the tunnel. During the night, our works will largely take place below ground. Works above ground will usually take from 7am to 6pm Monday to Friday, and 8am to 1pm on Saturdays. Occasional out of hours work may be necessary and we will keep you informed about this.

How disruptive will these works be?

We are committed to carrying out our works with minimal impact on the local community. We have completed an environmental assessment for each site and are agreeing Construction Environmental Management Plans and Construction Logistics Plans with the relevant local authority before we start works. The tunnelling works are carried out deep beneath the ground, therefore it is unlikely that there will be any noticeable noise or vibrations. We will monitor these issues throughout the construction programme.

Will the works cause traffic congestion?

One of the reasons for building a tunnel is to avoid traffic congestion on the busy roads in and around London. However, there will be some construction traffic as a result of our work. Please be assured, this will be kept to a minimum and will be managed. Our Construction Logistics Plans are being agreed with the relevant local authority.

What measures will be in place to mitigate this impact?

We will do all we can to minimise any disruption associated with our construction traffic. This includes:

  • Building temporary access roads, which will route construction traffic to our sites, avoiding the need to use main roads.
  • Managing HGV movements and avoiding peak morning and evening times where possible.
  • Promoting car share incentives.

What are you doing to benefit the community?

As part of our ongoing commitment to the communities in which we work, we are partnering with social enterprise, MyKindaFuture, to deliver a Science, Technology, Engineering and Mathematics (STEM) and careers engagement programme with secondary schools across the route. Our activities will give pupils the opportunity to participate in National Grid interactive STEM workshops, and we will also deliver careers fairs and online mentoring for students in years 12 and 13. The scheme will be rolled out from September 2020 to coincide with the new academic year, subject to COVID-19 social distancing restrictions. Find out more about it here (link to MKF page)

How much power will the new cables deliver?

Upon completion, London Power Tunnels Phase 2 will be capable of transmitting summer electrical power flows of 1091MVA and winter flows of 1240MVA. This is equivalent to approximately powering 500,000 kettles.

How will you keep us informed throughout the project?

We have a community relations team in place who will keep you informed about our works through:

  • Public information events
  • Project updates by letter or newsletter
  • A dedicated community phone number
  • Local media
  • Project website

If you would like to discuss the project in more detail or have any questions, please contact our community relations team using the details below:

Call our Freephone helpline number: 0800 783 2855

Email: [email protected].