Motorists in Somerset encouraged to plan ahead as crucial engineering works to enable low-carbon energy project take place

  • National Grid is encouraging motorists who travel in and around Somerset to allow extra time for journeys as crucial engineering works mean overnight closures to two sections of the M5 motorway.
  • Closures have been planned with National Highways, North Somerset Council and Bristol City Council overnight to cause the least disruption.

As part of the Hinkley Connection Project, which will deliver home grown low-carbon energy to six million homes and businesses, wires need to be installed on a section of the newly constructed T-pylons next to the M5 and lowered and removed from existing pylons.

To protect residents, road users and people working on the project, the M5 will be closed between junctions 19 and 21 in both directions overnight for three nights in April and two nights in June, so that scaffolding needed for the works can be erected and then removed when the work is completed. The closures have been planned for midweek and overnight when there is least traffic.

Northbound, there will be a full diversion route in place from J21 for all vehicles along the A370 and the A4 to re-join the motorway at J18. There is an additional diversion route for light vehicles only from Clevedon along the B3130 and B3128 to the A370.

Southbound, there will be a full diversion route in place from J18 for all vehicles along the A4 and A370 to re-join the motorway at J21. There is an additional diversion route for light vehicles only from J19 along the A369 and B3128 to the A370.

Overnight on Friday, 12 May, there will also be a closure of all carriageways on the junction 18a slip road of the M5 at Avonmouth. This is to enable lowering and recovery of ropes used during the dismantling and removal of the existing 132kV wires in the area, between Portishead substation and Avonmouth substation.

Bristol City Council has confirmed its Clean Air Zone charge will be lifted on the diversion routes while this work to help connect low carbon energy to homes and businesses takes place.

Date of overnight closures

Time of closure

Location of closure

Tuesday 25 April
Wednesday 26 April
Thursday 27 April

10pm to 5am

M5 Junction 19 to 21 in both directions

Friday 12 May

10pm to 2am

M5 Junction 18a slip road in both directions

Saturday 10 June
Sunday 11 June

10pm to 5am

M5 Junction 19 to 21 in both directions












Additional road closures with full diversions in the area during this period are:


Date of closure

Time of closure

Location of closure

Tuesday 11 April – Sunday 18 June

Full closure

Caswell Hill

Wednesday 12 April – Sunday 7 May

Full closure

Sheepway Road

Monday 15 May – Friday 9 June

Full closure

Causeway, Nailsea


Aden Precious, Project Manager for overhead lines on National Grid’s Hinkley Connection Project said: “These closures are important to ensure the safety of all road users and our workers as we continue our work to construct this crucial, nationally significant low-carbon electricity infrastructure. We work closely with National Highways and local authorities to do all we can to minimise disruption and have planned these closures overnight when there is least traffic on the roads. We apologise for any inconvenience and longer journey times during these periods.”



Notes to Editors:

The Hinkley Connection Project is a new high-voltage electricity connection between Bridgwater and Seabank near Avonmouth. It's a significant investment in the region’s electricity network and will enable us to connect new sources of home grown low-carbon energy to homes and businesses, including Hinkley Point C.

It will play a vital role in delivering electricity safely, efficiently and reliably, and support the UK’s ambition to achieve its net zero by 2050 target.

Significant milestones include:

  • Construction and commissioning of two substations, at Shurton and Sandford.

  • Installation of 8.5km of underground cable under the Mendip Hills Area of Outstanding Natural Beauty.

  • Construction of Loxton Cable Sealing End, next to the M5 where the T-pylons connect into the underground cables.

  • 150 existing pylons removed to date.  249 in total will be removed from the Somerset landscape as part of the project.

  • Energisation of the new high-voltage electricity connection between Bridgwater and Sandford, including 36 of the world’s first T-pylons.

The project has to date awarded more than £1.1 million in community grants to 75 different projects in areas nearby and ensured access to the latest science and technology equipment for more than 400,000 local pupils in the South West through the Hinkley Connection Project Education Fund.

The Hinkley Connection project began construction in 2018 will be ready to connect to Hinkley Point C by the end of 2024, with the project complete, including reinstatement at the end of 2025.

National Grid in the UK

National Grid sits at the heart of Britain’s energy system. The individual companies in our group run the networks and infrastructure that connect millions of people to the electricity they use every day.

Our regulated businesses own and develop the high-voltage electricity transmission (ET) network in England and Wales, and the electricity distribution (ED) network in the Midlands, South West England and South Wales. The electricity system operator (ESO) is the legally separate (and in the process of becoming fully independent) arm of our group that manages supply and demand on Britain's electricity transmission networks. Operating separately from these core regulated units, National Grid Ventures (NGV) focusses on competitive markets, investing in energy projects, technologies and partnerships such as electricity interconnectors.

We bring energy to life, with an ambition to serve our customers well, support the communities in which we operate, and make possible a clean, affordable and resilient energy network of the future.

Find out more about the energy challenge and how National Grid is helping find solutions to some of the challenges we face at

National Grid undertakes no obligation to update any of the information contained in this release, which speaks only as at the date of this release, unless required by law or regulation


Contact for media information only:

Helen Blake +44 7790 824788