Project Update – September 2025

Welcome to the latest round up of construction activity at Sizewell C.  We are pleased to announce our SMS alert service is now live, the community can now sign up to receive works tracker updates via SMS as well as email. Click here to subscribe Sizewell C Works Tracker - Track SZC Projects & Get Alerts for New Activities via the login button.

Firstly, thank you for your patience as we work hard to get new infrastructure in place, such as park and ride facilities to bus our workers into site and improvements such as the A12 Two Village Bypass and Sizewell Link Road.  We are sorry for the inconvenience this is causing and will work to complete these essential projects as quickly as possible whilst providing updates to communities so you can plan your journeys. With this in mind, the Sizewell C works tracker and One Network Causeway one.network are guides to works in the area and the new subscription service through our works tracker will also help with transport plans around the county.

We are working across the county and wider East Anglian region to improve Sizewell C related road signs, which includes removing temporary signs and replacing them with permanent road signs. This will ensure contract drivers are taking the correct routes.  Closer to site, we are also replacing temporary road signs along the B1122 with permanent speed reduction and camera signs.

As part of our accommodation strategy, we announced at the last Northern Transport Forum that we have acquired part of the Darsham High Lodge site which will provide accommodation for our workforce. High Lodge benefits from being closely located to the Darsham Railway Station and the Northern Park and Ride site. A bus service will be available for workers to transport from High Lodge to site, keeping cars off the road.

We have started to build a widened and improved layby on the A12 to assist police escorting our wide load HGVs. Working closely with Suffolk County Council, we have closed one of the lanes of the dual carriageway. This is to ensure traffic flow and not create a bottleneck along the dual carriageway by ensuring a consistent one lane traffic flow from Woodbridge. We are working with Suffolk County Council to review the traffic management requirements and aim to remove the cones as soon as we can. In the meantime, the measures are also necessary to also ensures road safety for road users and workers, and Suffolk County Council will be undertaking maintenance work during this time. The traffic management will be in place until December.

Archaeological Works and Discoveries

Our main archaeology contractor, Oxford Cotswold Archaeology, has made significant progress this year across our sites, discovering some fascinating finds. Recently, one of our eagle-eyed truck drivers spotted something which turned out to be a 36,000-year-old Neanderthal handaxe. Read more on the Oxford Cotswold Archaeology website.  Oxford Cotswold Archaeology will be exhibiting findings from some of our sites in October. They will be hosting an in-person event at the Riverside Centre in Stratford St Andrew on 25 October from 10am to 4pm. They’ll also be holding an online event, ‘Reshaping the archaeological landscape: an introduction to the excavations associated with Sizewell C‘, on 8 October.

Temporary Construction Area (TCA)

On the Temporary Construction Area we are preparing for the installation of the foundations for our water desalination plant. Our main access road on the site is operational and we are continuing to install utilities ready for our worker welfare facilities and construction activities.

The foundations for the concrete batching plant, which will serve Sizewell C throughout construction, are also being poured. Having a plant on site is much more efficient than transporting concrete from off-site, further helping to reduce the number of HGVs on the roads.

Sizewell Beach and Harbour Area

The construction of the northern section of the Temporary Sea Defence is continuing with sheet piles being installed. We have installed 45 sheet piles on the North Mound. These interlocking steel sheets will create a continuous retaining wall that provides excavation support. Our earthworks team have now started to backfill the area ahead of the next phase of the work for the Combined Discharge Outfall drainage system.

We have started investigative works in preparation for the Marine Bulk Import Facility, also known as the jetty. These works will involve some construction plant and divers, public access along the beach will be protected and managed by temporary protection barriers and marshals.

The construction of the collar at the top of a 26-metre deep shaft has started, the shaft will allow seawater to be pumped to the desalination plant.

We have submitted a planning application to East Suffolk Council to raise the southern end of the flood defences from 7ft to 10ft to align with Sizewell B.

Further details of these works and more information on our marine and harbour activities can be found on the Sizewell C Works Tracker.

In and around Leiston

The site where the plaza roundabout will be built continues to be prepared for construction.   Over the coming months there will be further traffic management and road closures as we build a rail level crossing over Abbey Road.

The first phase of these works has started and due to be complete on Monday 6th October. This involves building a temporary road that will link the B1122 to Lover's Lane and then back onto the B1122 / Abbey Road. All road users will be required to use this temporary diversion from Monday 6 October whilst the new level crossing is constructed.  Further details can be found on the Sizewell C Works Tracker.   The works will also include further utility adjustments by Essex and Suffolk Water. There will also be daytime traffic management in place.

We are installing permanent road signs across Suffolk and East Anglia to make sure our workforce and contract partners follow the correct approved routes to and from our sites.   Permanent speed limit signs and average speed camera signs are being installed along the B1122.

From the start of October, we will start preparing the site for the College on the Coast with Heras fencing being erected along the boundaries and preparation for archaeology and utilities works.

Net Zero Leiston has reached agreements with all landowners hosting bicycle racks for a Net Zero Leiston Cycle Scheme - Pedal to Zero. Bicycle racks were installed in early September, with bikes delivered shortly after, and the scheme launched in late September. The locations where bikes can be used from include the East of England Co-op, Leiston Town Council Office, Leiston Community Centre, The Waterloo Centre and Leiston Leisure Centre.

Community Road Improvements

We have written to residents and communities who live along the B1078 to outline upcoming road safety improvements, including speed reductions at different points along the road. The overall improvements are between the A140 junction with the B1078 and Wickham Market and include new signs, village gateway signs, improvements to visibility at junctions and areas of carriageway resurfacing. This work will be carried out towards the end of the year.

The average speed cameras along the B1122 and B1125 are currently powered using solar panels and UK Power Network are currently installing mains electricity connections to supply power during the winter.

Two Village Bypass and Friday Street Roundabout

Along the route of the Two Village Bypass we have completed archaeology, tree and ecology clearance and access works at Tinker Brook have also finished. The technical approval for the Friday Street roundabout has now been received from Suffolk County Council, and archaeology is nearly complete.

There is significant traffic management along the A12 as we carry out these works which are continuously reviewed, checked and maintained.  For example, we have reduced distance of the required 30mph speed restrictions at Tinker Brook Lane.

Sizewell Link Road

Galliford Try, the main contractor for the Sizewell Link Road, has started work on site. Initial works include establishing a compound for worker welfare and equipment, as well as constructing a haul road, setting up temporary fencing and the diversion and upgrade of underground utilities. A review of the road speed along the A12 has resulted in the reduction of distance of the 30mph speed limit at Town Farm Lane.

Yoxford Roundabout

Works at Yoxford Roundabout remain on track to open in the spring of 2026. Vegetation and ecology surveys have been completed allowing for utility diversions to take place. Earth movements are also ongoing.

Northern Park and Ride, Darsham

Galldris, the Principal Contractor for the Northern Park and Ride, continues to build the new roundabout off-line from the A12 while keeping works and disruption on the carriageway to a minimum. Earthworks on the site are nearing completion with main construction continuing. A phased operation of the park and ride site will start in autumn.

Southern Park and Ride, Wickham Market

Galldris also continues work on the Southern Park and Ride, including earthworks and the construction of their compound. Main construction will start later this month. A phased operation of the park and ride site will start towards the end of this year.

The ongoing works along the A12 to support the construction of the Southern Park and Ride include installing a power line to the site that will run from a connection point on the A12 at Marlesford.  The works require temporary traffic lights along the A12 from the Farm Shop and will move along the A12 as the work progresses. The work is due to be completed at the latest in early November.

The ongoing Cadent gas pipe diversions and upgrades on the northbound slip road finished in September and the B1116 works will continue until 10 October which will include temporary traffic lights.

Rail Works

Balfour Beatty Rail has commenced the track upgrade on the Sizewell Branch Line. A 3.7km length of continuous welded track has been installed between Bratt’s Black House and Summerhill level crossings. This has included laying and tamping of new ballast, installing new sleepers and welding together sections of rail to create a continuous track which will reduce noise during operations.

During September we have been installing the new junction near to Hodgson Avenue, where the new Green Rail Route will start before heading to the north of Leiston to the Temporary Construction Area. In October we will upgrade the track to the east of Summerhill level crossing. Also in October, work will commence on the Leiston Level Crossing on Abbey Road.  This will involve traffic management and road closures, further details will be outlined in due course.

The archaeology along the Green Rail Route is nearly complete, which will allow the earthworks to complete with install of the new track from late October.

Our rail team is preparing for the construction of the railheads at the Ancillary Construction Area and Temporary Construction Area, starting in September and October respectively.

Rail Replacement Works - Sizewell C Works Tracker