The new A122 would be approximately 23km long, with 4.25km of this in a tunnel under the River 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.

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

Overview map of the Lower Thames Crossing

Most 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 – instead 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, apart from the tunnel where enhanced operational and technology measures would be used.

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.

Once built, the new road would provide more reliable journeys across the Thames between Kent, Thurrock, Havering and Essex. It would also improve connections to the busy ports in the South East and better manage the high volume of HGV traffic crossing the river.

Further information on the proposed route and its features can be found in chapter 2 of the Operations update.

Chapter 4 of the Operations update provides an overview of our transport modelling work to assess the need for, and impact of, the A122 Lower Thames Crossing on the road network, junctions and bus routes. This looks at the forecast impacts over a wider geographical area than the ward impact summaries.

Our transport model simulates the transport system in the Lower Thames area and is called the Lower Thames Area Model (LTAM). It provides information on how the road network is predicted to perform in the future with and without the new crossing, known as the ‘do something’ and ‘do minimum’ scenarios.

When the new road opens, some of the traffic that currently uses the Dartford Crossing is predicted to divert to the Lower Thames Crossing because it would offer a shorter route and provide additional road capacity. Some of the space this creates at the Dartford Crossing would be taken up by motorists who were not using it before due to the high traffic levels and unpredictable journey times.

The transport model predicts that:

• The level of daily traffic using the Dartford Crossing would fall on average by 21% in 2029 and 14% in 2044 compared to the ‘do minimum’ scenario.
• Average speeds on that part of the network would rise and journey times would become more reliable.

If the Lower Thames Crossing is not built, it is expected that the high levels of traffic using the Dartford Crossing would lead to more incidents, increased journey times and more days where traffic conditions are worse than typically experienced.

Figures 1 and 2 show the predicted change in the anticipated amount of traffic on the road network as a result of the Lower Thames Crossing in the opening year (2029).

Roads contained within the transport model are shown in varying shades of blue, if traffic levels are forecast to decrease and in yellow to red if they are forecast to increase. The darker the colour, the greater the change. The route of the Lower Thames Crossing is shown in green.

Overall, the impact on traffic flows with the Lower Thames Crossing would be similar during the morning, evening and inter-peak periods, with the changes more pronounced and covering a wider area during the morning and evening peaks.

On many roads to the west of the project, such as the A2, the A13, the Dartford Crossing and the M25 in Thurrock, the number of vehicles would fall when the Lower Thames Crossing opens. However, roads on the approach to the new crossing, including the M2, A228, A229, some roads to the east, such as the A13, the A2, and some sections of the M25, would experience an increase in traffic levels as travel across the river becomes easier and more reliable.

 

As a result of the Lower Thames Crossing, there are predicted to be improvements in how the road network operates around the Dartford Crossing and on other roads in Gravesham and Thurrock. On the wider road network, conditions would remain largely unchanged. Congestion is predicted to increase on some roads, particularly those close to the project.

For example, in the morning peak, in the ‘do minimum’ scenario, the percentage of volume (the number of vehicles using a road) to road capacity (the number of vehicles a road can carry) is predicted to be above 95% on a number of roads. These include critical areas like the Dartford Crossing, sections of the M25, A2, A12, A13, and A228, and areas around Basildon and Rochester.

In the ‘do something’ scenario, the Lower Thames Crossing is predicted to improve the operation of the road network in the morning peak around the Dartford Crossing, as well as on the M20 and on parts of the M25, A13 and A2. However, there are some increases in the percentage of volume to capacity on sections of the M25 north of the Lower Thames Crossing, on the A13 to the east and on the M2, as traffic switches away from the M20 onto the new route.

Bus routes

There are likely to be impacts on the journey times of some bus and coach services if the traffic speeds of the roads they use change once the new road opens. Most routes would not be affected and the impact for an individual passenger would depend on where they get on or off a particular service. For example, a commuter coach service along the A2 would travel at a lower speed east of the new crossing but at a higher speed west of it.

Further information on specific bus routes that would be affected can be found in chapter 4 of the Operations update.

To construct the Lower Thames Crossing, works would need to be carried out to the existing utility networks to make sure customer supplies are maintained. We would therefore need to divert, relocate or protect the existing utility infrastructure.

New connections to the existing networks would also be necessary for the operation of the new road.

All of the work to existing utilities that would be needed for the project would be managed and programmed with the relevant utility network operators and follow their procedures and regulations. This would minimise disruption to the network and its customers. Where possible, we would complete works at the same time to reduce any impact on the surrounding road network.

Further information on effected utilities can be found in chapter 2 of the Operations update.

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. In determining these, we considered:

• connections to employment
• connections to education
• recreational/green space connectivity
• addressing historic severance

Further information on these opportunities can be found in chapter 2 of the Operations update.

Seven new green bridges would connect these new pathways, including the widest in the UK on Thong Lane. This would triple the number of green bridges currently in the UK. These would connect local communities and create safe crossing places for wildlife, connecting habitats and colonies, while also helping to integrate the road into the landscape.

When the Lower Thames Crossing is open it is important to understand its likely environmental impacts and how we would mitigate these. Chapter 5 of the Operations update focuses on these impacts, which have been identified through environmental assessments, and our proposed mitigation measures over the area of the project. The topics covered include:

• air quality
• noise and vibration
• geology and soils
• minerals and waste
• road drainage and water environment
• climate and carbon
• landscape

Information on localised environmental assessments can be found in our Ward impact summaries.

Although during operation of the Lower Thames Crossing some areas are predicted to experience decreases in air quality due to changes in traffic flows across the region, there will be improvements in others and an improvement in air quality in the project wide area overall.

This could affect receptors (such as people’s homes or sensitive habitats) that are located close to the route or those in locations where traffic flows on the wider road network. The change in concentrations of pollutants has been assessed.

In the opening year, the assessments show that there would be localised increases on certain roads, such as the M2 junction 1 to 2 and parts of the A228, causing air quality to worsen and in some cases exceed the national air quality objective for NO2.

However, the results also show numerous air quality improvements, such as around the A282 Dartford Crossing (where existing air quality is poor) due to significant reductions in traffic and congestion in this area.

In total, 24 receptors are expected to experience a change in air quality in those areas where concentrations of pollutants are expected to exceed the air quality objective, set by the government. Of these 24 receptors, 15 are predicted to experience an improvement in air quality. The remaining nine are predicted to experience worsening air quality once the route is open.

Air quality is assessed across the whole scheme, taking into account the improvement and reduction in air quality. The air quality assessment concludes that there would be no significant effects from NO2 and particulate matter. As a result, mitigation is not proposed.

Impacts on noise levels once the new road opens include increases in traffic noise at sensitive receptors, such as people’s homes or on ecological species, along the route and on some existing roads.

Reductions in the sound of traffic at noise sensitive receptors in other locations are predicted as traffic is diverted along the new road. These include areas along the A2 between the Lower Thames Crossing and the A282 (junction 2), the A282 across the Dartford Crossing, the A13 between the new road and junction 30, and the M25 between the junction with the new road and the A282.

Through developing our proposals we have reduced the potential noise impacts by locating the road as far as reasonably practical away from noise-sensitive locations. We have also designed the new road to be at a low level, with approximately 80% of the route below ground level in a cutting, false cutting or tunnel, and used earthworks where possible to reduce noise.

Mitigation measures will also include the use of low-noise road surfacing technologies on new and resurfaced roads and acoustic noise barriers at certain locations along the route where earthworks measures are not possible.

Impacts from road traffic vibration would not be significant because the Lower Thames Crossing new road surface would be constructed in accordance with highway specification that ensure a smooth road surface.

During the operation of Lower Thames Crossing, there is a risk of soil being contaminated from surface water and groundwater from road spray and pollution incidents and from traffic accidents (for example fuel or oil spillages).

To mitigate these potential impacts, the drainage network would include special devices to capture any contaminants to avoid polluted water infiltrating into the surrounding soil.

We’re also proposing to include tunnel waterproofing and barriers around excavations required during construction to reduce effects on groundwater. Good practice mitigation measures, such as the removal of contaminated soils after pollution incidents, would be put in place to prevent contamination spreading into the wider environment.

With these proposed measures, no likely significant effects on geology and soils are predicted during operation.

During the operation of the Lower Thames Crossing, maintenance works, for example, road resurfacing, would need lower quantities of materials compared to construction, which would have a lower impact on resources and product supply.

It is anticipated that minor quantities of waste would be produced from offices at the tunnel entrances and from maintenance repairs. Practices to reuse, share and recycle waste would also be implemented.

Impacts on the water environment after the Lower Thames Crossing opens are likely to come from drainage from the road, which has the potential to cause changes to groundwater levels and quality. Permanent cuttings and embankments could also affect groundwater by acting as a drain, lowering the groundwater table, or reducing the ability for rainfall to soak in. Operation of the tunnel also has the potential to cause groundwater levels to drop, which may draw in saline waters or risk contaminating the ground.

Areas of land to the north of the River Thames around the site where the northern tunnel entrance would be located are currently at risk from flooding due to the low-lying geography of the area. The Lower Thames Crossing is not at risk of flooding to the south of the river.

With the implementation of proposed mitigation measures, including drainage systems, flood bunds, flood relief channels and compensatory flood storage areas, and allowance for projected climate change effects, no significant adverse effects on road drainage and the water environment are predicted after the Lower Thames Crossing opens. Some localised beneficial effects on flood risk and land drainage are predicted.

GHG emissions will be generated when the Lower Thames Crossing is open through additional road traffic, energy consumption and the maintenance, repair, and replacement of the infrastructure.

When we confirmed the route for the Lower Thames Crossing, the estimated change in GHG emissions was assessed as 5.98m tCO2e over the 60-year appraisal period.

Since then we have developed more detailed assessments and continue to update these to take into consideration refinements to the project, traffic forecasts and the influence of policy and other factors on the forecast emissions from different vehicle types.

Our work focuses on the impact of the Lower Thames Crossing over its full 60-year appraisal period from opening. We will continue this work, considering the ongoing development of government policy and guidance, for our planned DCO application later this year.

To reduce GHG emissions when the Lower Thames Crossing is open, the following items have been included as part of the proposals:

• trees, shrubs and hedgerows planted as part of the landscape design
• maintaining existing and providing new connectivity for walkers, cyclists and horse riders through public rights of way, and providing road users with potential alternatives to vehicles
• electricity during operation would be sourced from renewable suppliers
• low-energy light sources, for example, light-emitting diode (LED) or equivalent technology, would be used (subject to emergency lighting requirements) to reduce energy consumption

In addition, measures have also been incorporated into the design to increase the Lower Thames Crossing’s capacity to be resilient to the effects of climate change. These include:

• establishing future flood risks in consultation with the Environment Agency
• designing parts of the new road with consideration to our flood risk assessment, which has influenced aspects of the design such as the height of the road, watercourse crossings and protection measures at the northern tunnel entrance
• incorporating flood alleviation measures into the design to reduce the risk of flooding, including earthworks to protect the northern tunnel entrance, provision for a flood relief channel and removal and/or enlargement of culverts.

When the Lower Thames Crossing is open, it would create a noticeable addition to the landscape. To the south of the River Thames, landscape effects would include the loss of woodland due to the widening of the A2 corridor, the introduction of the junction of the new road with the A2 and additional road lighting. There would also be changes to overhead electricity lines and towers.

To the north of the River Thames, the most noticeable changes would include the raised Tilbury Viaduct, road embankments and the enlarged A13 junction. Further north, the elevated road through the flat Orsett Fen landscape and various viaducts and bridges would be noticeable. Existing overhead electricity lines to the north of the River Thames will also be realigned to allow for the new road.

Other likely significant effects on the landscape and views are likely to include permanent adverse effects on the landscape character of the Kent Downs Area of Outstanding Natural Beauty (AONB) and intermittently on the local landscape along the route corridor.

Vegetation would be planted to provide screening along parts of the route. This would mature over time and therefore the visual effects would generally reduce after 15 years.

To avoid or reduce any adverse effects, mitigation measures such as landscaping earthworks, have been incorporated into the design of Lower Thames Crossing so that it integrates into the landscape.

Approximately 80% of the new road has been set in cutting, false cutting or in the tunnel providing visual screening. Other measures include:

• replacing lost landscape features for example hedgerows and woodland
• provision of green bridges
• creating new woodland around the A2, A13 and M25 junctions with the new road
• planting vegetation along the route to screen views of the road and to help integrate it into the landscape.

Cumulative impacts are when two or more types of effects combine to cause impacts on the environment. These could be ‘intra-project effects’ where a receptor or location would experience more than one effect, or ‘inter-project effects’ where there would be impacts from the project in combination with other nearby projects which are either in construction or are planned.

Intra-project effects

The intra-project cumulative effects assessment considers locations that could experience more than one effect (for example air quality and noise and vibration impacts) as a result of the Lower Thames Crossing.

The assessment will review all predicted effects for the various environmental topics on locations likely to be affected. It is possible that multiple effects would combine when the new road is open to result in likely significant effects on some receptors. This would vary between geographical areas and all receptors would not experience the same impacts, magnitude or significance of effects.

The Ward impact summaries provides a description of predicted effects by ward but at this stage a detailed assessment of the likely intra-project cumulative effects has not been included. It is only possible to understand these effects once all other environmental topic assessments have been completed. These will be presented in the Environmental Statement on the submission of the application for development consent.

Inter-project effects

Nearby projects are being identified and considered in the inter-project effects assessment along with the combined effects of the Lower Thames Crossing and other developments. Each of the projects identified would have a responsibility to include mitigation within their proposals to avoid or reduce adverse effects on the environment and comply with relevant legislative requirements.

The list of nearby projects continues to be reviewed and updated for the inter-project effects assessment for our DCO submission. Other developments to be considered in the inter-project effects assessment include:

• Thurrock Flexible Generation Plant
• The London Resort
• M25 junction 28 Improvement Scheme
• various mixed use and residential developments
• various solar parks
• Thames Estuary 2100 long-term strategy for managing tidal flood risk in the Thames Estuary
• the Freeport