Lower Thames Crossing supplementary consultation - Building the Lower Thames Crossing

Closed 2 Apr 2020

Opened 29 Jan 2020


Building the Lower Thames Crossing

This chapter provides an update on how we are proposing to build the Lower Thames Crossing. The predicted impacts of our construction activity and how we propose to mitigate these are based on the information we currently have available.

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To set out how we would manage construction of the project, we will develop a Code of Construction Practice (CoCP), in conjunction with statutory consultees and local authorities. This will include provisions aimed at minimising disruption to communities, mitigating impacts on the wider environment, and our approach to managing construction traffic.

The provisions of the CoCP will be based on the findings of the Environmental Impact Assessment, which will be documented in our Environmental Statement (ES). Both the CoCP and ES will be submitted as part of our DCO application.

If the project is approved and progresses to construction, the contractors we appoint will need to prepare and submit for approval their own Construction Environmental Management Plans (CEMPs). These will ensure the contractors’ work is delivered in line with the CoCP.

During construction, we will give affected residents, businesses and road users advance notice of planned works and provide regular updates on project progress. We will also keep disruption to a minimum on public rights of way used by walkers, cyclists and horse riders. We will do this by limiting full route closures and providing alternative routes. Wherever a right of way is affected, we will provide a nearby alternative.

Wherever possible we will protect – and look for opportunities to enhance – the local environment and improve biodiversity.

For a summary of the environmental impacts of building the Lower Thames Crossing, please see section 6 and our Environmental Impacts Update document.

Construction hours

Once we start on site, the new roads and tunnel would be constructed concurrently.

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To maximise the amount of daylight hours during construction, we are increasing our assumed core working hours from those presented during statutory consultation. We are planning 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.

From time to time we may have to carry out maintenance work on Sundays. We will 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 disruption to drivers during the day.

Operation of the tunnel boring machines and associated activities for tunnel construction will 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.

Tunnelling work

It is likely to take around six years to build the tunnel and the road within the tunnel. We are not changing the plans presented in the statutory consultation for how we propose to construct the tunnel under the River Thames.

Ground preparation works

The local ground conditions mean we expect a number of ground treatment measures would be required as part of the Lower Thames Crossing tunnel works. These will strengthen specific areas of the ground or help control groundwater flows.

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During construction we would aim to keep road closures to a minimum.

The local ground conditions mean we expect a number of ground treatment measures would be required as part of the Lower Thames Crossing tunnel works. These will strengthen specific areas of the ground or help control groundwater flows.

To treat the ground beneath the Thames Estuary and Marshes Ramsar site and Special Protection Area, we are proposing to build a ground preparation tunnel that is 5.8 metres in diameter (see diagram below). It would be located above and in between the northbound and southbound tunnels. This is subject to the contractor’s proposals.

This construction activity would take place south of the river. It would start from a shaft located south of Lower Higham Road, and travel to a shaft located north of the North Kent Railway Line. Once the works are completed, both the shafts and ground preparation tunnel would be backfilled, and the ground reinstated to its original condition. The potential environmental effects of the new tunnel have been noted in our Environmental Impacts Update.


Building the roads

As described during statutory consultation, we plan to build the new roads, junctions, bridges and underpasses at the same time as the tunnelling work.

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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 the 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.

To facilitate the construction of the Lower Thames Crossing, where required, we would modify some of the existing side roads and infrastructure along the route.

How we would use other public roads

During construction, we would aim to keep road closures to a minimum. Where roads are affected by closures and diversions, temporary traffic lights or lane restrictions, we would ensure road users know in advance, so they can plan their journeys accordingly. Later in this chapter, we have outlined the routes our heavy goods vehicles (HGVs) are likely to take to transport material to and from our construction sites. Below we have detailed the average number of HGV journeys per month for each of our five construction areas, with each HGV journey comprising one trip to the site and another away from it.

Following engagement with local highway authorities and our ongoing assessments, we have amended the routes that construction traffic would use to travel to the sites. We have aimed to identify those that are most practicable and that minimise the impact on local roads and communities. Where there are no roads to the construction site, we would build temporary access roads that connect to the existing network.

Roads to the construction sites

The Lower Thames Crossing is split into five construction areas labelled A-D. As we now have a greater understanding of our construction requirements and the potential routes construction vehicles will use to access the sites, we have been able to update the information available during our statutory consultation.

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We also have more information on how we can use and reuse material on our construction sites more efficiently, which will reduce the need for material deliveries and vehicle movements. Where material has to be transported from elsewhere, we better understand the capabilities of the local supply chain and expect most of this to be supplied from nearby locations. We are also continuing to explore opportunities for alternative modes of transport, such as river barges, to transport materials and waste to and from our construction sites.

(Click on the lettered icons in the image below to view the information.)


We have provided revised figures for the potential number of HGV movements in the table below, with a brief description of why this information has changed on the following pages.

Construction area Average number of HGV journeys/
month displayed during statutory
consultation 2018
Average number of HGV
journeys/month – based on
updated information
Area A 4,700 2,900
Area B south 1,100 800
Area B north 4,500 5,300
Area C 5,200 2,100
Area D 2,000 2,200
Total 17,500 13,300


Area A: We have been able to significantly cut the number of potential HGV journeys by assessing how material can be reused on our construction site to create embankments and landscaping that would help mitigate the impacts of the road.

Area B South: Moving the tunnel entrance further south has enabled us to reduce the number of HGV journeys. The maps on the following pages show the routes that construction vehicles are likely to use. The map for Areas A and B South shows a construction area over the tunnel route; no part of this is an above ground structure and would not impact on the sensitive ecological area between the southern tunnel entrance and the river.

Area B North: The potential number of HGV journeys has increased as the design of the project in this area has been updated and more information has become available. We are exploring opportunities to reduce the number by transporting material via the river.

Area C: Following further design developments in this area, we have been able to make a better assessment on how material will be reused. This has enabled us to significantly reduce the number of HGV journeys on the road network.

Area D: Following further design developments in this area, we now have a better understanding of how material is required to be used for construction. There is an increase in material needed for this construction area, which has caused a slight increase in the potential number of HGV journeys on the road network.

The maps below show the construction areas and the routes that construction vehicles are likely to use.

Each road has been marked in a different colour, depending on whether it is a main or secondary route, and the long or shortterm access requirements. These are based on our current plans and are subject to change as a result of our ongoing dialogue with local highway authorities.

Routes to service construction


Construction impacts on local roads

As described at statutory consultation, most of the construction materials would be transported to the construction sites by road, which would have some impact on the road network and its users. Since then, 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 are likely to use the local and Strategic Road Network.

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Construction could affect local roads through temporary closures, diversions, traffic lights and/or lane restrictions. Should the project receive consent and progress to construction, we will provide advance notice of disruption, so people can look for alternative routes or travel arrangements.

At this stage, we can provide high-level information about the planned construction on specific roads, and have outlined this in the table below. On all roads we would ensure access is maintained to properties through the use of traffic management and/or by providing diversion routes.

We previously assessed the impacts of construction on local roads and presented this during statutory consultation. The information in the table on the next page is an amended evaluation that incorporates the traffic impacts of construction. The predicted possible impacts have been classified as follows:

High: Disruption associated with construction activities, which could include a high volume of construction vehicles, and/or possible long-term closures (months to years) with diversion routes provided.

Medium: Potential for some disruption associated with construction activities, which could include increased use by construction vehicles, and/or medium-term closures (weeks to months) with diversion routes provided.

Low: Minimal disruption associated with construction activities, with a low number of construction vehicles relative to road capacity, and/or roads to remain open with potential for shortterm weekend/night-time closures or lane restrictions.

Note: During construction, where the Lower Thames Crossing crosses a local road, there may be some traffic management required, for instance traffic lights, to enable construction vehicles to cross safely.

Please note: Roads impacted by the utilities works are not included in the table below. There is however the possibility that there will also be road diversions, closures and restrictions associated with the utility works. The full extent of this information would be submitted as part of our DCO application.

Road affected Planned construction Possible impact
predicted at statutory consultation 2018
Possible impact of current proposals
Brewers Road Replacement of the bridge carrying Brewers Road over the M2. This is a long-term closure with considerable construction activity on the bridge crossing the M2. High High
Thong Lane Replacement of the bridge carrying Thong Lane over the A2, plus a new bridge carrying Thong Lane over the LTC. This is not a main construction route but there is potential for weekend/night closures. Low Low
A2 (near the
LTC junction)
New bridge and underpass at the LTC junction with the A2. There will be considerable work on and around the A2. There will be weekend/night closures, mainly with narrow lane traffic management and reduced speed limits. There will be no longterm or full closures. Medium Medium
Station Road New viaduct to carry the LTC over Station Road. There will be limited construction vehicles using Station Road. Low Low
New bridge to carry Muckingford Road over the LTC. Shortterm weekend/night closures and a requirement for short-term construction route access. Low Low
Hoford Road New bridge to carry Hoford Road over the LTC. Short-term weekend/night closures. Low Low
New bridge to carry Brentwood Road over the LTC. The road will be used for construction access, mainly between the LTC and the Orsett Cock roundabout. There will be very limited HGV journeys south of the LTC, beyond High House Lane. Low Low
Hornsby Lane We have removed the bridge to carry Hornsby Lane over the LTC, which was displayed during statutory consultation. We will permanently close the road and there will be no access over the LTC. During construction there will be a low number of construction vehicles using the road. Low High
Heath Road Closure of Heath Road owing to A1013 works and creating emergency access. Closures limited to weekend/nights. Low Low
A1013 New bridges to carry the A1013 over the LTC, A13 and A1089. Short-term weekend/night closures and the road will be used for access to construction working areas. Medium Medium
A1089 New viaduct and bridges at the LTC junction with the A13 and A1089. Weekend closures are likely to be required. The A1089 would be used as a main construction route. Medium Medium
Baker Street New viaduct and bridges at the LTC junction with the A13 and A1089. The realignment of the road will require a long-term closure. Low High
A13 New bridges at the LTC junction with the A13 and A1089. There will be considerable work around the A13 and shortterm weekend/night closures. The A13 will be used by a number of construction vehicles. Medium Medium
Rectory Road Replacement of the bridge carrying Rectory Road over the A13 in the same location. A long-term closure is therefore required, but access to the hospital will be maintained at all times either via Rectory Road or Baker Street. Low High
Stifford Clays
New bridges to carry Stifford Clays Road over the LTC and slip roads. The road will be used as a route to access our construction sites just north of the A13 on a short-term basis, until an offline access is created. Design changes at the A13 junction meant we could no longer access these directly off the A13. There is potential for weekend/night closures. Low Medium
Green Lane New bridge to carry Green Lane over the LTC. Our access routes to construction sites have changed due to design development around the A13. Green Lane is now being used as a main access to our construction sites, and there is potential for a long-term closure. Low High
B186 Warley
Street, Clay Tye
& North Road
New bridge to carry the B186 North Road over the LTC. Roads will be used for short-term access to the construction site. Medium Medium
M25 (at the LTC
New structure to take the LTC under the M25. There will be considerable construction activity in the area but no planned closures. High Medium
Ockendon Road New bridge to carry Ockendon Road over the LTC and M25. Long-term closure will be required to facilitate the bridge over the M25 and slip road. Medium High
St Mary’s Lane Replacement of the structure taking St Mary’s Lane under the M25. There will be construction activity associated with building the new underbridge. The road is a short-term access route to the construction site, and there is potential for short term closures. Low Low
M25 junction 29 Widening of the Codham Hall viaduct carrying the M25 over the A127. The road will be used by a large number of construction vehicles and we expect to narrow the lanes to reduce road user speed during construction. High Medium
A127 Widening of the Codham Hall viaduct carrying the M25 over the A127. We expect to use lane closures/narrow the road to facilitate widening the viaduct. Low Medium

Construction sites

A number of construction sites are needed to build the Lower Thames Crossing. They have been positioned along the route based on our construction requirements and provide access for our workforce and material deliveries.

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At our five main sites, you would be likely to see temporary buildings and storage areas, including offices, space for equipment and materials, parking and staff welfare facilities. Our secondary sites are smaller sites, which will typically include welfare facilities, materials and equipment. Some sites would have a bespoke set-up depending on the work involved, such as the tunnel construction area at the northern and southern entrance sites, our two largest construction sites.

At the northern entrance site, we would construct a temporary substation to provide power for the tunnel boring machines. It would also power a water treatment facility, a separation facility to process the excavated material and other facilities to support tunnel construction. A new permanent substation would also be located in the service area next to the northern tunnel entrance to provide permanent power to the northern side of the tunnel.

There would be fewer facilities to support tunnel construction at the southern entrance site. As we expect to begin our tunnelling north of the river, most of the infrastructure would be located at the northern entrance site. South of the river, there would be some office and welfare facilities for our construction workers visible. Construction work associated with the earthworks operation around the tunnel entrance would also be visible. We are currently working with the utility companies to assess locations for an electricity substation within the temporary construction site in this area.

The majority of our construction sites will be reinstated and returned to their original use after construction is completed. However, some permanent above-ground infrastructure would remain at the northern and southern entrance to the tunnel.

A tunnel service building would be constructed at each entrance site to service the tunnel through its life cycle, and to ensure that it can be operated and maintained safely. These buildings would accommodate technical, operational and welfare facilities for our construction workers.

New job opportunities would be created during construction, which would boost both the local and regional economies. For our construction workers, we are currently assessing housing availability in the surrounding areas and reviewing how much temporary accommodation we would need. We expect to house some of the workforce within our construction sites and are looking to provide some of this accommodation at the northern entrance site.

The details of workforce accommodation will be agreed between Highways England and the construction contractor.

Due to the volumes of material that will be excavated near the southern tunnel entrance, we will be creating temporary stock piles within the construction sites to store some of the material. These will be transported off site once construction is finished to reduce the impact on the road network.

The five main construction sites are in yellow on this map, while our smaller, secondary sites are displayed in pink. In some cases, the location of these has changed or been reshaped as a result of statutory consultation feedback.

Construction sites

The information below outlines how the main construction sites differ from those displayed during statutory consultation:

  1. Has not changed from statutory consultation
  2. Reshaped to avoid an archaeological site
  3. More efficient design requiring less land
  4. Moved further south with the south tunnel entrance, and extended west to provide additional space for temporary material stockpiling
  5. Has not changed from statutory consultation

Other sites of note:

  1. These sites close to the A13 have been refined following feedback from statutory consultation to reduce the impact on nearby properties
  2. These are extensions of the south entrance site, which will be used to mitigate works associated with the ground preparation tunnel

Have your say
To comment on our updated proposals for building the Lower Thames Crossing, please answer question 5a and 5b in the response form.

Continue to the next section: Section 8: Utilities

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