Project Spotlight: Lower Thames Crossing

Balfour Beatty, Costain, Lower Thames Crossing, Skanska,

April 27, 2026

The Lower Thames Crossing is one of the most significant transport infrastructure projects currently in development in the United Kingdom.

With an estimated cost of over £8–9 billion, it represents a major investment in road capacity, freight efficiency and long-term economic growth across the South East.

Positioned east of London, the project will create a new road connection beneath the River Thames, linking Kent and Essex and relieving pressure on the heavily congested Dartford Crossing, currently the only road crossing of the Thames east of London.

Project Overview

At its core, the Lower Thames Crossing will deliver a new 23km road connection, including what will be the longest road tunnel in the UK, running approximately 4.2km beneath the River Thames.

The project includes:

Twin bored tunnels under the Thames
New and upgraded motorways connecting the M2 and M25
Over 50 bridges and structures
Extensive environmental mitigation works, including landscaping and habitat creation

Once complete, the crossing is expected to significantly reduce congestion at Dartford, improve journey reliability and unlock freight efficiency between key logistics hubs and ports in the South East.

Tunnelling contract awarded for Lower Thames Crossing in the UK

Delivery Model and Key Players

The project is being developed by National Highways, formerly Highways England, which is responsible for England’s strategic road network.

Given the scale and complexity, the project has been split into multiple major works packages, with several Tier 1 contractors and global engineering firms involved.

Main Works Contractors (MWCs)

National Highways has appointed three main works contracts:

Roads North (M25 side):

Balfour Beatty
Skanska
AtkinsRéalis

Roads South (Kent side):

Costain
Bouygues Travaux Publics

Tunnels & Approaches:

BAM Nuttall
Ferrovial Construction
Vinci Construction

These consortia bring together a mix of UK, European and global expertise, particularly in large-scale tunnelling, complex road networks and major infrastructure delivery.

National Highways awards Balfour Beatty the 1.2B Lower Thames Crossing contract

Planning Status and Timeline

The project received its Development Consent Order (DCO) submission in 2022, marking a major milestone in the UK planning process for nationally significant infrastructure.

As of the latest updates:

Planning approval is expected following government review
Construction is anticipated to begin shortly after consent
The build programme is expected to take approximately 6–7 years

Current projections indicate a potential opening in the early to mid-2030s, although timelines remain subject to final approvals and funding confirmation.

Engineering Complexity

The Lower Thames Crossing is a highly complex civil engineering undertaking.

Key challenges include:

Constructing one of the UK’s longest road tunnels beneath a major river (Thames)
Managing ground conditions including chalk, clay and water ingress
Integrating new infrastructure with live motorway networks (M25, M2, A2)
Delivering major structures while minimising environmental and community impact

The twin-bore tunnel design will require advanced Tunnel Boring Machines (TBMs), similar to those used on major global projects such as Crossrail and European alpine tunnels.

Economic and Strategic Importance

The Dartford Crossing currently carries far more traffic than it was designed for, leading to frequent congestion and delays that impact both commuters and freight.

The Lower Thames Crossing is expected to:

Increase road capacity across the Thames east of London
Improve resilience of the strategic road network
Reduce journey times and delays
Support regional growth and logistics efficiency

It is also considered a key enabler for economic development across the Thames Estuary, often described as one of the UK’s major future growth corridors.

Environmental Considerations

A major focus of the project has been environmental mitigation and design sensitivity.

Planned initiatives include:

Extensive green bridges and wildlife crossings
Noise reduction measures
Landscaping to integrate the road into surrounding areas
Biodiversity net gain commitments

Despite these measures, the project has also attracted scrutiny and opposition, particularly around carbon impact and local environmental disruption, a common theme for infrastructure projects of this scale in the UK.

Hiring and Market Implications

From a recruitment perspective, projects like the Lower Thames Crossing are significant.

Large-scale infrastructure of this nature typically drives demand across:

Project Engineers and Senior Engineers
Tunnel specialists and geotechnical engineers
Site Engineers and Supervisors
Commercial and project controls professionals
Health, Safety and Environmental specialists

While the project is UK-based, it reflects a broader global trend: major infrastructure investment continues to underpin demand for experienced civil engineering professionals.

For markets like Australia and New Zealand, where similar large-scale projects are underway, there is ongoing competition for talent with international experience, particularly in tunnelling and major transport infrastructure.