After more than a decade of debate, redesigns and political uncertainty, the Lower Thames Crossing is finally moving from concept to construction. With works now scheduled to begin in 2026 and an expected opening in the early 2030s, the £10 billion scheme is being positioned as the most significant road infrastructure project the UK has seen in a generation.
The announcement follows confirmation in the Autumn Budget that a further £891 million will be allocated to the project, building on the estimated £1.2 billion already spent on planning, design and statutory approvals since proposals were first tabled in 2009. For National Highways, this funding secures the final stages of public investment between 2026 and 2029, after which construction and long-term operation will move into a private-sector delivery phase.
At its core, the Lower Thames Crossing is designed to address a long-standing strategic weakness in the UK’s road network. The Dartford Crossing currently carries far more traffic than it was ever designed for, routinely bringing the M25, A2 and A13 to a standstill. National Highways estimates that the new crossing could divert more than 10 million vehicles a year away from Dartford, significantly improving network resilience across the South East.
The scheme will create a new 14.5-mile motorway-style route linking the A2 and M2 in Kent with the A13 and M25 in Essex. Its centrepiece is a 2.6-mile twin-bore tunnel running beneath the River Thames, which, once complete, will be the longest road tunnel in the UK. With three lanes in each direction, the crossing is expected to nearly double road capacity east of London and strengthen connections between the South East, the Midlands, the North and key freight routes serving ports along the Thames Estuary.
Beyond capacity and connectivity, the project is also being framed as a test case for a new approach to large-scale road building. National Highways has repeatedly described the Lower Thames Crossing as potentially the greenest road ever built in the UK. Around 80 per cent of the route will either be underground or concealed behind landscaped embankments, with the aim of reducing visual intrusion and protecting sensitive environments between Gravesend and Tilbury.
Seven new green bridges are planned, including one that is expected to be the widest in Europe, allowing wildlife, pedestrians and cyclists to cross the route without direct interaction with traffic. The design also includes extensive use of pre-fabricated bridge components to reduce on-site disruption, low-carbon footbridges constructed without concrete, and gantries designed to minimise both steel use and visual impact.
From a construction perspective, the Lower Thames Crossing represents a major opportunity for the industry. National Highways has stated that the project will be built by local people and businesses, with a strong emphasis on skills development, apprenticeships and long-term employment across Kent, Essex and the wider South East. If delivered as planned, it will act not only as a transport corridor but as a catalyst for regional growth and supply-chain investment.
For the construction sector, however, the scale of the scheme also brings scrutiny. Cost control, programme certainty, carbon performance and community impact will all be closely watched as the project transitions from planning into delivery. With motorists not expected to use the route until around 2032, the coming years will be critical in determining whether the Lower Thames Crossing lives up to its promise.
As previously explored by London Construction Magazine when the scheme was revived after years of delay, the project’s significance goes well beyond a single river crossing. It is a litmus test for how the UK plans, funds and delivers nationally important infrastructure in an era of economic pressure, environmental responsibility and public accountability.
The announcement follows confirmation in the Autumn Budget that a further £891 million will be allocated to the project, building on the estimated £1.2 billion already spent on planning, design and statutory approvals since proposals were first tabled in 2009. For National Highways, this funding secures the final stages of public investment between 2026 and 2029, after which construction and long-term operation will move into a private-sector delivery phase.
At its core, the Lower Thames Crossing is designed to address a long-standing strategic weakness in the UK’s road network. The Dartford Crossing currently carries far more traffic than it was ever designed for, routinely bringing the M25, A2 and A13 to a standstill. National Highways estimates that the new crossing could divert more than 10 million vehicles a year away from Dartford, significantly improving network resilience across the South East.
The scheme will create a new 14.5-mile motorway-style route linking the A2 and M2 in Kent with the A13 and M25 in Essex. Its centrepiece is a 2.6-mile twin-bore tunnel running beneath the River Thames, which, once complete, will be the longest road tunnel in the UK. With three lanes in each direction, the crossing is expected to nearly double road capacity east of London and strengthen connections between the South East, the Midlands, the North and key freight routes serving ports along the Thames Estuary.
Beyond capacity and connectivity, the project is also being framed as a test case for a new approach to large-scale road building. National Highways has repeatedly described the Lower Thames Crossing as potentially the greenest road ever built in the UK. Around 80 per cent of the route will either be underground or concealed behind landscaped embankments, with the aim of reducing visual intrusion and protecting sensitive environments between Gravesend and Tilbury.
Seven new green bridges are planned, including one that is expected to be the widest in Europe, allowing wildlife, pedestrians and cyclists to cross the route without direct interaction with traffic. The design also includes extensive use of pre-fabricated bridge components to reduce on-site disruption, low-carbon footbridges constructed without concrete, and gantries designed to minimise both steel use and visual impact.
From a construction perspective, the Lower Thames Crossing represents a major opportunity for the industry. National Highways has stated that the project will be built by local people and businesses, with a strong emphasis on skills development, apprenticeships and long-term employment across Kent, Essex and the wider South East. If delivered as planned, it will act not only as a transport corridor but as a catalyst for regional growth and supply-chain investment.
For the construction sector, however, the scale of the scheme also brings scrutiny. Cost control, programme certainty, carbon performance and community impact will all be closely watched as the project transitions from planning into delivery. With motorists not expected to use the route until around 2032, the coming years will be critical in determining whether the Lower Thames Crossing lives up to its promise.
As previously explored by London Construction Magazine when the scheme was revived after years of delay, the project’s significance goes well beyond a single river crossing. It is a litmus test for how the UK plans, funds and delivers nationally important infrastructure in an era of economic pressure, environmental responsibility and public accountability.
👉 See our earlier analysis: Lower Thames Crossing revived as government backs flagship infrastructure scheme
If successful, the Lower Thames Crossing could redefine how major road projects are delivered in the UK. If it falters, it risks reinforcing long-held concerns about cost overruns and delays. Either way, with construction now firmly on the horizon, the industry will be watching closely as Britain’s biggest road project finally breaks ground.
