Sizewell Point C nuclear plant faces a fresh construction setback after delays hit two major access roads in Suffolk. The £38.2 billion nuclear development needs these routes to manage construction traffic. However, the project has replaced its main road contractor after commercial negotiations failed. The change could delay completion by six months to one year.
The setback comes as the project seeks to demonstrate that it can avoid problems experienced at Hinkley Point C. Sizewell C uses the same EPR reactor technology as its sister nuclear project. It also plans to replicate elements of Hinkley Point C’s design and construction approach.
The latest road problem therefore creates fresh scrutiny over Sizewell C’s construction delivery strategy. It also threatens to prolong disruption for communities surrounding the Suffolk construction site.
Sizewell Point C Nuclear Plant Access Road Construction Faces Delay
Galliford Try originally secured the contract for the Sizewell Link Road and Two Village Bypass. The package carried a reported value between £150 million and £200 million.
The contractor started preliminary construction work last year. However, Galliford Try failed to reach agreement with Sizewell C over costs for the main construction phase.
The disagreement followed several design changes affecting the road package. One person familiar with the project said those changes added about £30 million to costs.
Kier and Suffolk-based Breheny Civil Engineering have now taken over the road-building package. They will split the remaining work between them.
The contractor change creates a significant program challenge for Sizewell C. The project had expected both roads to reach completion during 2026.
The Sizewell Link Road will provide a 6.5km route around Theberton and Middleton Moor. The Two Village Bypass will provide a 1.8km route around Farnham and Stratford St Andrew.
Sizewell C had planned these roads to reduce heavy construction traffic through surrounding villages. Consequently, the delay could extend disruption for local residents.
Sizewell Point C Nuclear Project Faces Wider Construction Pressure
The road setback comes despite Sizewell C’s wider program of infrastructure development. The project continues work on transport infrastructure supporting its future construction activities.
The project has already opened new A12 roundabouts and expanded park-and-ride facilities. These measures form part of its wider strategy for managing construction traffic.
However, the delayed roads remain particularly important to the construction logistics strategy. Their purpose includes diverting heavy vehicles away from villages during the main construction program.
Sizewell C chief executive Nigel Cann acknowledged that the road program was running behind schedule. He told MPs that the project remained focused on securing the right commercial price.
Cann also said Sizewell C avoided rushing into the main works with insufficient design development.
Nevertheless, the delay creates another test for the project’s delivery model. The government designed that model to reduce construction and financing risks.
The National Audit Office identified major delivery risks in its latest assessment of Sizewell C. It noted that comparable nuclear projects have experienced delays or cost increases.
The watchdog also confirmed a £38.2 billion baseline construction cost. It expects construction completion by summer 2039. The project could generate electricity from 2038 and operate for at least 60 years.
Sizewell C reached its Final Investment Decision in July 2025. The project now has government and private investors supporting its delivery.
The current ownership structure includes the UK government, EDF, La Caisse, Centrica and Amber Infrastructure.
The road delay does not currently indicate a change to the nuclear plant’s overall construction target. However, it adds pressure to a program designed around schedule certainty.
The project must now coordinate Kier and Breheny while maintaining its wider construction sequence. It must also minimize additional disruption around surrounding communities.
For Sizewell C, the immediate priority remains recovering the road program without creating further cost or schedule pressures.
Project fact sheet
Project: Sizewell C nuclear power station.
Location: Suffolk, England, United Kingdom.
Project type: Nuclear power generation and supporting infrastructure.
Nuclear technology: Two EPR reactors.
Planned capacity: Approximately 3.2GW.
Baseline construction cost: £38.2 billion.
Expected electricity generation: From 2038.
Construction completion target: Summer 2039.
Planned operating life: At least 60 years.
Electricity supply: Equivalent to six million homes.
Final Investment Decision: July 2025.
Financing model: Regulated Asset Base model.
Sizewell Link Road length: 6.5km.
Two Village Bypass length: 1.8km.
Original road contractor: Galliford Try.
Replacement contractors: Kier and Breheny Civil Engineering.
Original road contract value: £150–£200 million.
Reported additional design-related cost: Approximately £30 million.
Expected road delay: Six months to one year.
Main purpose of roads: Divert construction traffic from nearby villages.
Wider transport measures: Rail, sea freight and park-and-ride facilities.
Main reactor technology supplier: EDF.
Project team
Developer: Sizewell C Ltd.
Government shareholder: UK Government.
Nuclear partner: EDF
Investors:
Former road contractor: Galliford Try
Road contractors:
- Kier
- Breheny Civil Engineering.
Government department: Department for Energy Security and Net Zero.
Nuclear technology: EDF EPR.
Financing structure: Regulated Asset Base model.
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