Lower Thames Crossing

Infrastructure and Construction

Record date: 31 March 2026

Whole-life cost: £9.9bn
Published schedule: 30/05/2014 – 31/07/2035
NISTA delivery confidence: AMBER
Senior responsible owner: Kate Cohen

What the project is for

The Lower Thames Crossing (LTC) is a proposed new road connecting Kent, Thurrock and Essex through twin-bored tunnels under the River Thames. It will almost double the road capacity across the River Thames east of London and is the largest single road investment project in the UK since the M25 was completed more than 30 years ago. As a vital part of the UK’s transport infrastructure, it will act as a catalyst for national and local economic growth. Building a reliable, modern new road that is fit for the future will help connect the nation's busiest ports to the distribution hubs in the North, Midlands and beyond. It will improve network resilience and the performance of the existing crossings at Dartford, transforming the regional and national road network. The LTC will open up new markets for businesses and create tens of thousands of new jobs and hundreds of apprenticeships during its construction. At Autumn Budget 2025 it was confirmed that the Government's preferred financing option at this stage of the project is the Regulated Asset Base (RAB) model which will allow for a regulated private entity to finance, build, operate, and maintain the asset under long-term oversight by an independent regulator. Under the RAB model, operations of the Dartford Crossing would transfer to a new regulated private sector entity, which would be responsible for operating and maintaining both the Dartford Crossing and the new LTC. The project therefore now incorporates the work required to create the legislative, regulatory and commercial framework for the RAB model.

Departmental delivery commentary

Compared to financial year 24/25 Q4, the SRO Delivery Confidence Assessment (DCA) rating at 25/26 Q4 improved from Amber to Green. This is primarily due to the following factors‚ The LTC project secured additional public funding with £1.66bn in the Third Road Investment Strategy for the years 2026/27 and 2028/29 which includes the £891m announced at Autumn Budget 2025 and funding previously committed for those years. The Government also confirmed in 25/26 that the preferred finance model at this stage of the project is the Regulated Asset Base (RAB) model. This strengthens confidence in delivery and steps are being taken to prepare for a transaction with the private sector. The NISTA DCA rating for 25/26 Q4 is Amber, whilst we recognise that there are still risks to delivery, the SRO is content that sufficient mitigations were in place as of March-26 and therefore rated the DCA as Green. The project DCA is reviewed monthly. The Outline Business Case was updated and approved by the DfT Investment Committee in October 2025. This marks the transition from full public sector funding to a future private sector RAB model, with the private sector to deliver the remainder of the scheme and take on Dartford Crossing operations in 2028. The DfT team working on the project has expanded to reflect the new work required on legislation and regulation, and the SRO role during 25/26 moved from National Highways to DfT to reflect this broader scope.

Schedule

The project was granted Development Consent on 25 March 2025. The project was re-baselined in October 2025 to inform Autumn Budget 2025 decision making where the Regulated Asset Base (RAB) model was selected as the preferred financing model. An Accounting Officer Assessment was undertaken to support this decision. The project remains on course to deliver as set out at Autumn Budget. We expect the existing Dartford Crossing and LTC project to move from public to private ownership in 2028. The main tunnelling phase for the LTC is expected to begin in 2028 and the target date for the road to be open for traffic is the early to mid-2030’s .

Cost

Compared to financial year 24/25-Q4, the projects departmentally agreed Whole Life Cost at 25/26-Q4 (measured in £m) increased from £8950,220m to £10629,020m. This is primarily due to schedule delay, the first delay was due to affordability and planning consent delays as set out in the Written Ministerial Statement issued 9 March 2023 which re-phased construction by 2 Years. A further delay to the DCO decision was announced by the Secretary of State in October 2024 extended the decision deadline to May 2025. The cost increase incorporates the prolongation and inflationary impacts following these two schedule delays which required the project to re-baseline. It should be noted that it is the intention to split the Whole Life Cost between both Public and Private finance under the Regulated Asset Base model. The transition to private finance is currently expected to occur in 2028. To note: the figures in the Annual Assessment may differ to those in this narrative due to NISTA deflating costs forecast for later years.

Benefits

The current approved benefits at 25/26-Q4 remained at £3,009m. This figure is based on the project being fully publicly funded and is now outdated due to the approval to move to a Regulated Asset Base (RAB) model. The VfM analysis will continue to develop as detail on policy assumptions evolves, alongside any updates to our appraisal approach. For example, the department has made the decision to take forward LTC on the basis of the Regulated Asset Base model (RAB) and has published its intention to adopt new, higher values of time for freight movements. The strategic case for the LTC project remains strong. As well as the connectivity and congestion relieving benefits delivered by the new crossing, which leads to major economic benefits, this is also based around the escalating need for maintenance of the Dartford Crossing. The Dartford Crossing is already operating significantly over capacity and suffers from poor reliability. As with any major project, there are significant risks to be managed in order to realise the project’s benefits. We will continue to work with NISTA and apply lessons from the James Stewart review of High Speed 2 to help minimise those risks. Further work will be completed in the next stages of the programme up to FBC at which point the accounting officer assessment will be refreshed. As the benefits are expected to be felt for several decades, the figures in the Annual Assessment may differ to those in this narrative due to NISTA deflating benefits post 2050.