Designing and building the Lower Thames Crossing
It’s vital to get the design, construction and operation of the Lower Thames Crossing right to maximise its benefits and minimise its impact
The Lower Thames Crossing has been classified as a Nationally Significant Infrastructure Project, which means it will be developed in phases:
We will use construction techniques that minimise disruption. This includes the bored tunnel method, which will minimise impacts on the riverside marshes and riverbed, and offsite construction, which enables faster progress and use of the river for transporting materials.
The Lower Thames Crossing opens to traffic.
*We are using a date range of 2029 to 2030 to account for the natural uncertainty in developing a project of this size and scale. As we gather more information from consultation, our ground investigations and engagement with the supply chain, we will gain more certainty.
Our application for a DCO was submitted on 31 October 2022, and it was accepted for examination by the Planning Inspectorate on 28 November. The DCO process is expected to run until 2024. Read more about that here.
Following our design refinement consultation last summer, we submitted a DCO application to the Planning Inspectorate in October 2020. However, based on early feedback, we withdrew the application in November 2020.
Highways England holds a second public consultation.
The Secretary of State for Transport announces the preferred route, a tunnel under the River Thames east of Garvesend and Tilbury (location C, route three with the Western Southern Link).
DfT asks Highways England to assess the economic, traffic, environmental and community impacts for locations A and C.
Location C is recommended as it offers far greater economic benefits and congestion relief.
A public consultation asks for feedback on proposals and location C, including 3 routes north of the river in Thurrock and Essex, and two south of the river in Kent.
The response to the consultation confirms the need for a new crossing between Kent, Thurrock and Essex. Option B is ruled out; the remaining two locations (A and C) are investigated further.
The DfT carries out a public consultation to ask for views on the location of the proposed crossing.
The DfT commissioned a study to assess the 3 remaining location options.
The government recognises the need for a new crossing by naming it a top 40 priority project in its National Infrastructure Plan.
Owing to increasing demand at the Dartford Crossing, the DfT looks at options for an additional crossing at five potential locations (A, B, C, D and E). The two furthest east are ruled out as they are too far from the existing crossing. Rail is also ruled out.
The design for the Lower Thames Crossing aims to find the right balance between providing value for money, moving traffic effectively, and reducing the impact on local communities and the environment.
We have liaised closely with residents, community groups, businesses, local authorities and regulators over the past few years to develop our designs. We have also been working with external agencies that are experts in this field, including the Design Council, to make sure our approach to design has been guided by the relevant standards and best practice.
Since presenting our detailed proposals in our 2018 statutory consultation, we have made considerable progress in developing the Lower Thames Crossing project. We have been refining the design, updating our traffic model and carrying out extensive environmental and geotechnical surveys, all while continuing to engage with our stakeholders.
We will shortly submit our Development Consent Order (DCO) application to the Planning Inspectorate.
The Planning Inspectorate will examine our application before making a recommendation to the Secretary of State. If it is approved, we will be awarded a DCO. This gives us permission to build.
Our proposed work sections
Given the complex nature of construction, we would divide the works into four sections to help make sure they are delivered on time with the minimum impact on local communities, the environment and road users. These would be:
- Section A: south of the Thames in Kent, to include works along the M2/A2 corridor, the proposed junction with the M2/ A2, and all other carriageway works as far as (and including) the proposed Thong Lane North Bridge over the new road.
- Section B: to the north of Thong Lane North Bridge, as far as the proposed Tilbury Viaduct. This includes the works to build the tunnel and its approaches south and north of the Thames.
- Section C: from (and including) the proposed Tilbury Viaduct, as far as (and including) Green Lane, north of the proposed A13/A1089 junction with the new road.
- Section D: north of Green Lane, to include works through the Mardyke Valley, along the M25 corridor and around junction 29 of the M25.
Construction in each section would typically cover three main phases of work:
- initial works, including setting up the construction compounds
- main works, covering the construction of the highways north and south of the Thames and all elements of the tunnels and their approaches, as well as utilities and environmental mitigation works
- testing and commissioning, in which we make sure the new road and its infrastructure is safe and ready for use.
During construction, we would carry out activities typically associated with major infrastructure projects. This includes:
- building retaining walls
- road resurfacing and widening works
- culverts, drainage works and flood compensation
- removing topsoil and temporary soil storage
- management of excavated material and earthworks
- drainage and flood compensation
- bridge and viaduct construction
- temporary lighting
- site fencing and hoarding
- installation of gantry and signage foundations
- tie-in and finishing works
Before the main construction work can begin, we would need to acquire land and prepare the site. This would include:
- diverting public rights of way and utilities
- creating new habitats
- carrying out flood avoidance measures
- species relocation
- removing vegetation as necessary
- making any contaminated land safe
- completing detailed surveys about the land and surrounding area
We would build the new roads and tunnel in phases. This would be the most efficient way of working and would allow different elements of the project to be completed at the same time.
We would use construction techniques that minimise disruption. This would include the bored tunnel method, which reduces impacts on the riverside marshes and riverbed, and offsite construction, which enables faster progress and use of the river for transporting materials.
To maximise the amount of daylight hours during construction, we would plan to carry out most of the work between 7am and 7pm on weekdays (excluding bank holidays), and between 7am and 4pm on Saturdays. During the summer, to take advantage of the extended daylight hours and good weather conditions, we would undertake earthworks between 7am and 10pm. Our crews may work for up to an hour before and after to prepare and close the site.
We would liaise closely with highways teams from the local authorities in each affected area to identify the best working times for each site, so these may vary.
As with any project of this scale, some work would have to take place at night and on weekends. For example, where possible, we would work on existing roads overnight to reduce daytime disruption to drivers.
During construction, we would give affected residents, businesses and road users advance notice of planned works and provide regular updates on project progress.
It is likely to take around six years to build the tunnel and the road inside the tunnel. This project is an enormous undertaking using the most sophisticated tunnelling techniques in the world.
Operation of the tunnel boring machines would take place 24-hours-a-day throughout. This would be confined to the tunnel entrances and within the tunnel, and we would put in place noise and light mitigation.
The local ground conditions mean we expect a number of ground treatment measures would be required to strengthen specific areas of the ground or help control groundwater flows.
We would plan to build the new roads, junctions, bridges and underpasses at the same time as the tunnelling work. To enable the construction of the Lower Thames Crossing, where required, we would modify some of the existing side roads and infrastructure along the route.
The new road would connect the M2/A2 in Kent with the M25 south of junction 29 in Essex, crossing the A13 north of Chadwell St Mary. To connect with these existing roads, as well as the A1089, we would construct new junctions and would have to carry out some work on these roads as well. This would include improvements to the M2/A2 and M25.
We now have a greater understanding of our construction requirements and the potential routes construction vehicles would use to access the sites. We also have more information on how we can use and reuse material on our construction sites more efficiently, which would reduce the need for material deliveries and vehicle movements.
Where material has to be transported from elsewhere, we would expect most of this to be supplied from nearby locations. We are also exploring opportunities for alternative modes of transport, such as river barges, to carry materials and waste to and from our construction sites.
At the moment most of the materials would be transported to the construction sites by road, which would have some impact on the road network and its users. Since our statutory consultation, we have refined our routes to the construction sites, continued our assessments and made further design changes. This has given us a greater understanding of how we would be likely to use local roads and the Strategic Road Network.
Construction could affect local roads through temporary closures, diversions, traffic lights and/or lane restrictions. If the project receives consent and progresses to construction, we would provide advance notice of disruption, so people can look for alternative routes or travel arrangements.
To support construction, it is likely we would need 18 compounds and 16 Utility Logistics Hubs. We would locate these away from environmentally sensitive areas and local communities wherever possible. However, they would need to service specific areas along the project route and provide access for staff and materials, so some would be near towns or villages.
Along the proposed Lower Thames Crossing, there are a number of existing utilities including overhead power lines, high-pressure gas pipelines, electric cables and substations, gas mains, water pipes, sewers and fibre-optic and telecoms cables that would need to be diverted to build the new road. Our proposals for utility works have evolved during the project’s design and development. We have been working closely with the utility companies to significantly reduce the environmental impacts and shorten the duration of the works. There should be no disruption to the supply of power, water or any other utilities caused by our construction work
When the Lower Thames Crossing opens for traffic, the direct, reliable connection would bring people closer to jobs, and businesses closer to their customers and suppliers.
The new A122 would be approximately 23km long, with 4.25km of this in a tunnel under the Thames. The tunnel would be located to the east of the village of Chalk on the south side of the river, and to the west of East Tilbury on the north side.
At the following locations, there would be:
- a new junction with the A2 to the east of Gravesend
- a modified junction with the A13/A1089 in Thurrock
- a new junction with the M25 between junctions 29 and 30
The majority of the road would be three lanes in both directions. It would use technology for incident detection, lane control and variable speed limits. The southbound connection from the M25 to the junction with the A13/A1089 would be two lanes, as would link roads and stretches of the carriageway through junctions.
In line with other A -roads, it would not have hard shoulders – but it would have narrower one -metre -wide hard strips along most of it. However, there would be hard shoulders along modified sections of the M25 and the A2. The new road would also have emergency areas at regular intervals, with the exception of the tunnel where enhanced operational and technology measures would be used.
We are designing a road that will be fit for the future.
The road will have a maximum speed of 70mph and a control centre will use live traffic information from cameras along the route to monitor and alter these speeds as needed. Signs on the road and in the tunnel will let drivers know what the current speed limit is. They will also provide further information in the event on an emergency.
Our proposals contain traffic regulation measures that include prohibiting use by pedestrians, low-powered motorcycles, cyclists, horse riders and agricultural vehicles.
All standard-height vehicles that use the road, including coaches and HGVs, will be able to use the tunnel without restrictions.
Although walkers, cyclists and horse riders will not be able to use the Lower Thames Crossing, we have developed a detailed set of proposals for maintaining, improving and upgrading the nearby walking, cycling and horse-riding network.
Working with local authorities and organisations such as Sustrans, a UK based walking and cycling charity, we have developed a programme of improvements for walkers, cyclists and horse riders that would connect local communities with green spaces and promote active travel choices.
Following statutory consultation and targeted stakeholder engagement, we developed a walkers, cyclists and horse riders strategy that examined the value of existing and potential routes. This was shared at our design refinement consultation.
A list of possible opportunities was developed that would result in 46km of new, realigned or improved footpaths, cycleways and bridleways.
It remains our proposal to apply a user charge for the Lower Thames Crossing, with a local resident discount scheme for those living in Thurrock and Gravesham.
The level of the charge and the charging regime would replicate the approach applied on the Dartford Crossing.
Therefore, the need for a Lower Thames Crossing charging consultation forum as suggested at statutory consultation is not considered necessary.