Public Rights of Way

Underground cable works in Dedham Vale

September 2026 to June 2027

National Grid is beginning the main construction phase of the Bramford to Twinstead Reinforcement. As part of these works, we need to install a new 400 kV underground cable in the Dedham Vale area. This involves digging trenches and installing ducts along the cable route.  Once this work is complete, trenches will be backfilled and we will restore the areas we’ve used.

During the works, where the cable route crosses a road, we’ll need to dig a trench and install the cable ducts beneath it. This will require some temporary road closures. We have applied for the necessary permits and are currently planning traffic management measures for November 2026. We’ll share confirmed closure details and diversion routes before they take effect, so you can plan your journey. You can see all upcoming closures in the dropdowns in the Traffic management section on this page. We apologise for any inconvenience this may cause.

We’ll carry out the work within the construction hours as outlined in the Development Consent Order (DCO) for the project. We will manage works to reduce disruption where we can. 

You can find out more about how we lay underground cables in this video here.

River Box Horizontal Directional Drilling (HDD)

28 September 2026 to January 2027

As part of the main construction phase of the Bramford to Twinstead Reinforcement, we’re also preparing to install ducts for the new 400 kV underground cable beneath the River Box. To do this, we will use horizontal directional drilling, which means we can drill under the river rather than dig through it. This approach reduces disturbance at the surface and avoids digging directly in the watercourse. The crossing beneath the river will be approximately 100 metres long.

We’ll set up temporary work areas on either side of the crossing to allow us to dig entry and exit pits, drill beneath the river and install the ducts. We’ll also remove and restore the temporary work areas after the relevant work is complete, in accordance with the project’s approved requirements.

The site entrances are already in place, so we do not expect to need traffic management for access to this work. We’ll carry out the work within the construction hours outlined in the Development Consent Order (DCO) for the project and will let people know in advance if activities may affect local access or cause disruption.

You can find out more about how we drill under rivers and roads in this video here.

Surveys

If a survey cannot take place on the scheduled date (due to factors such as poor weather conditions), we will endeavour to reschedule the survey in a timely manner.

Access to land plots is agreed before any surveys take place. If you are a landowner and have questions about surveys on your land, please get in touch via your usual point of contact or the details at the bottom of the page.

Completed works

South of Sudbury, work to build the new Twinstead Green grid supply point (GSP) substation has been progressing well. At Bramford substation, we have built the first gantries (metal structures) that will connect the new transmission line into the substation. We’ve also been working on the foundations for the first new pylons in this area and have carried out archaeological surveys at various locations.