Lower Thames Crossing: Route, Timeline, Cost, and What It Means for the Dartford Crossing

What Is the Lower Thames Crossing?

The Lower Thames Crossing is a new road tunnel under the River Thames, located approximately 14 kilometres east of the existing Dartford Crossing. It will be the longest road tunnel in the UK at 4.25 km, running between East Tilbury on the north bank and Chalk (near Gravesend) on the south bank. The crossing will have two bores, each carrying three lanes of traffic in one direction, providing six lanes in total.

The full project includes approximately 23 kilometres of new road connecting the tunnel to the existing road network. On the south (Kent) side, new roads will connect to the A2/M2 near Gravesend, providing a direct link to the Channel Tunnel, Dover, and the Medway towns. On the north (Essex) side, new roads will connect to the A13 and the M25 at Junction 29, near the Lakeside shopping centre and Thurrock.

The project is being delivered by National Highways (the same organisation that operates the Dartford Crossing) and is funded by the UK Government. The total estimated cost exceeds £8 billion, making it one of the most expensive road projects in British history. Construction is expected to create thousands of jobs in the Thames Estuary region.

Route Description

Starting from the south (Kent) side, the route begins with new road connections to the A2/M2 near Gravesend. The road passes through a mix of new cuttings and land bridges designed to minimise environmental impact before entering the tunnel portal near the village of Chalk. The tunnel itself runs for 4.25 km under the Thames, emerging at East Tilbury on the north bank.

On the north (Essex) side, the route continues through a new cutting before connecting to the A13 via a new junction. It then extends north to meet the M25 at a modified Junction 29, near Orsett. This northern section includes several new bridges and underpasses to maintain existing local road connections. The entire route has been designed as a high-standard dual carriageway with a 70 mph speed limit.

Project Timeline

The Lower Thames Crossing has had a long and complex planning history, spanning over a decade from initial proposals to the start of construction. The timeline below shows the key milestones, with the current stage highlighted.

Will the Lower Thames Crossing Be Tolled?

There has been no official announcement confirming whether the Lower Thames Crossing will be tolled. However, industry consensus is that tolling is almost certain. The project's estimated cost of over £8 billion, combined with the precedent set by the Dartford Crossing (which has been tolled since its tunnels opened), makes user charging extremely likely. The Development Consent Order includes provisions for a future tolling order, which strongly suggests that charges will be implemented.

Analysts expect the toll to be priced at a similar level to the Dartford Crossing — somewhere in the range of £3 to £5 per car crossing — with the possibility of a pre-pay discount similar to the Dart Charge system. There may also be a free period during off-peak hours, mirroring the 10pm-6am free period at Dartford. Local resident discounts for communities affected by the construction (particularly in Thurrock and Gravesham) are also considered likely.

The exact pricing will not be determined until closer to the opening date. If you are planning long-term financial decisions around commuting costs, budget for a charge similar to the current Dartford Crossing rate, and you will not be far off. We will update this page as soon as pricing details are announced.

Impact on the Dartford Crossing

National Highways estimates that the Lower Thames Crossing will reduce traffic at the Dartford Crossing by approximately 20-25%. This is significant — it would reduce the current 130,000+ daily vehicles to approximately 97,000-104,000, bringing the crossing closer to its designed capacity and dramatically reducing congestion during peak periods.

The traffic reduction will primarily come from vehicles currently using the Dartford Crossing to travel between the A2/M2 corridor in Kent and the A13/south Essex. These vehicles will have a more direct route via the Lower Thames Crossing. However, the Dartford Crossing will remain the primary route for M25 orbital traffic (vehicles staying on the M25), traffic to and from the Thurrock area, and traffic heading to and from north Essex and East Anglia.

What It Means for Regular Commuters

For regular Dartford Crossing users, the Lower Thames Crossing will be the most significant change to the Thames crossing network in over 30 years (since the QE2 Bridge opened in 1991). The practical impact depends on your specific route and commuting pattern.

If you currently use the Dartford Crossing to travel between the Medway towns or Gravesend area and south Essex, the Lower Thames Crossing will almost certainly become your preferred route. It will be more direct, potentially faster (especially during peak hours), and will avoid the congestion hotspot around the Dartford Crossing approaches. However, if it is tolled at a similar rate to the Dartford Crossing, the cost saving may be minimal.

If you use the Dartford Crossing for M25 orbital journeys (staying on the M25 to access other junctions), the Lower Thames Crossing will not directly change your route. However, you will benefit from the reduced traffic volumes at the Dartford Crossing. Commuters who currently experience 30-60 minute delays during peak hours may see these reduce to 10-20 minutes, which would represent a significant improvement in daily journey reliability.

History of the Project

The idea of a new Thames crossing east of London dates back decades. The Dartford Crossing, which opened its first tunnel in 1963 and the QE2 Bridge in 1991, was always designed to handle a certain volume of traffic. By the early 2000s, it was clear that traffic volumes had far exceeded that design capacity, with over 130,000 vehicles per day regularly using a crossing built for approximately 135,000. The margin for error was zero — any incident, breakdown, or adverse weather caused cascading delays.

A formal review in 2009 identified the need for a new crossing and evaluated multiple options including a new bridge, a tunnel near the existing crossing, and a tunnel further east. The decision to build a tunnel connecting the A2/M2 to the A13/M25 Junction 29 was announced in 2017, after extensive consultation and environmental assessment. This route was chosen because it provides the maximum traffic relief for both the Dartford Crossing and the surrounding road network.

The planning process proved lengthy and contentious, with significant opposition from local communities concerned about environmental impact, noise, and construction disruption. The Development Consent Order examination lasted over two years, and the final decision was not issued until 2024. Since then, the project has moved into the construction phase, with early works beginning in March 2026.

Environmental Considerations

National Highways has described the Lower Thames Crossing as "the greenest road ever built", with extensive measures designed to minimise environmental impact and enhance biodiversity. While this claim has been debated by environmental groups, the project does include significant mitigation measures beyond what previous road projects have delivered.

Key environmental features include over 650 hectares of new habitat creation (more than three times the habitat lost to construction), wildlife crossings and green bridges to maintain ecological corridors, noise barriers and low-noise road surfaces for nearby communities, and the use of electric construction vehicles where possible. The tunnel itself will be fitted with modern ventilation systems that filter exhaust emissions.

Carbon reduction measures include the use of lower-carbon concrete, recycled materials in road construction, and a commitment to achieving net zero carbon in the operation of the crossing. The construction phase will inevitably generate significant carbon emissions, but National Highways has committed to offsetting these through habitat creation and renewable energy procurement. The long-term environmental case for the project rests on the argument that reducing congestion at the Dartford Crossing will reduce the millions of hours vehicles currently spend idling in traffic jams.

Funding and Cost

The Lower Thames Crossing has an estimated total cost exceeding £8 billion, making it one of the most expensive road infrastructure projects in UK history. The funding has been allocated in stages by the UK Government, with key tranches confirmed in 2025.

The project is publicly funded through the Department for Transport. Future tolling revenue (if implemented) would contribute to ongoing operational and maintenance costs but is not expected to repay the construction cost directly.

Frequently Asked Questions