Lower Thames Crossing
Kent and Essex, UK · Preparatory works ongoing (c. 2026 onwards); Main construction expected to start 2026; Completion expected 2034. · £11 billion (estimated total project cost)
The judgement call
Account-gated at launchThe project aims to relieve congestion at the Dartford Crossing and improve connectivity across the Thames Estuary. - Significant focus on sustainability, aiming to be one of the greenest road projects in the UK. - The project has undergone extensive public consultation and planning processes due to its scale and impact. - Early works involve diverting major utility networks, a critical preparatory step for large infrastructure projects.
Key engineering challenges
Constructing the UK's longest road tunnel under the River Thames, requiring advanced tunnelling techniques. - Managing significant environmental impacts in a sensitive estuarial and agricultural landscape. - Integrating a major new road network with existing motorways (A2, M2, A13, M25) and local roads. - Addressing complex ground conditions and water management challenges during tunnelling and road construction.
Project facts
- Client / owner
- National Highways
- Lead contractor
- Skanska (for preliminary works on Kent Roads contract)
- Lead designers
- N/A (design is ongoing and involves multiple parties)
- Project type
- new build
- Scale
- Approximately 14.5 miles (23km) of new road; 2.6 miles (4.2 km) twin-bored road tunnel under the River Thames (longest road tunnel in the UK).
- Disciplines
- civil; structural; geotechnical; tunnelling; environmental; transport planning
- Standards & frameworks
- NEC4; DMRB; CDM Regulations
Sources: National Highways (https://nationalhighways.co.uk/our-roads/lower-thames-crossing/) - New Civil Engineer (https://www.newcivilengineer.com/latest/not-really-where-you-want-to-be-ground-preparation-for-lower-thames-crossing-tunnelling-06-01-2026/) - Skanska (https://group.skanska.com/projects/283946/Lower-Thames-Crossing-Kent-Roads-project) - ENR (https://www.enr.com/articles/60511-britain-approves-13b-lower-thames-crossing-project)