The tunnels will feature a 70mph speed limit and three lanes in each direction, connecting the M25 to Channel port traffic.

On March 25, 2025, the UK government announced planning approval for the £9 billion Lower Thames Crossing project, which will create the largest road tunnel in the UK under the River Thames, connecting Kent and Essex.

Transport Secretary Heidi Alexander confirmed the approval of the Development Consent Order by National Highways, which includes a 2.6-mile tunnel under the Thames, marking it as the longest road tunnel in the UK.

The project aims to nearly double road capacity across the Thames east of London, alleviating congestion and improving connectivity for millions of people.

Once operational in 2032, the tunnel is expected to reduce traffic at the Dartford Crossing by 20 percent.

Matt Palmer, executive director of National Highways, emphasized the project's commitment to low-carbon construction practices while promoting quicker, safer journeys.

Supporters, including businesses and local politicians, advocate the project's potential to reduce traffic chaos and drive economic growth, while some local councils and campaign groups oppose it due to environmental and social concerns.

Labour MP Jim Dickson emphasized that the decision will alleviate traffic chaos and promote economic growth in his constituency, addressing a long-standing issue for Dartford residents.

The project is expected to create new job opportunities during its delivery phase and stimulate significant regional growth.

National Highways is exploring private finance options to fund the project, with the government anticipating that tolls will help recover the estimated £8.95 billion baseline cost.

Local campaigners, Thames Crossing Action Group, argue that the project would be destructive and a misuse of funds.

Local communities were involved in a six-month examination of the project, allowing public input before the decision was made.