Building the crossing

* the start of the year depends on consent

We will carry out most of the work between 8am and 6pm on weekdays (excluding bank holidays), and between 8am and 4pm on Saturdays. These are standard hours for construction projects up and down the country, although crews may work for up to an hour before and after to prepare and close the site. From time to time we may also have to do some maintenance work on Sundays. We will work closely with highways teams from the local authorities in each affected area to identify the best working times for each site, so these times may vary.

As with any project of this scale, we will have to do some of the work at night. For example, where possible we will work on existing roads overnight to reduce disruption to drivers going about their daily journeys. Tunnel construction will be a 24-hour operation throughout.

Most of the construction work will take place during the day

Have your say

To comment on our construction plans, answer question 11 on the response form.

Next we will prepare individual sites for construction. We expect to tackle the most complex sites, including the tunnel, M25, A13 and A2 junctions, first.

Find out more

To find out more about construction, see Approach to Design, Construction and Operation.

Tunnelling work could begin from either the northern or southern entrance. Based on the information we currently have, we expect to begin near the northern entrance. Two machines will excavate the tunnel, which will then be lined with precast concrete segments.

On average, a tunnel boring machine excavates at a rate of between 50 and 125 metres a week, depending on the model.

This is very similar to the tunnel boring machine we plan to use

This project is an enormous undertaking using the most sophisticated tunnelling equipment in the world. It will mean underground construction and activity will take place 24 hours a day, seven days a week to complete the tunnel as soon as possible. It is standard practice during 24- hour operations to put in place special measures such as noise barriers to keep potential impacts to a minimum.

During construction, we will make sure we keep residents, businesses and road users informed of planned works in advance and share information on progress.

Machines will excavate the tunnel, which will then be lined with precast concrete segments

A significant number of HGV journeys will be needed to transport material to and from the sites. An estimate of the average number of HGV journeys per month for each of the five construction areas is shown on pages 110-113, with each HGV journey making one trip to the sites and another away from the sites. The maps also show the areas where construction traffic may travel. The exact routes will be agreed at a future stage of the project.

We will carefully plan which roads construction traffic will use to reach our sites

We will carefully plan which roads construction traffic will use to reach our sites. Where there are no roads to the construction site, we will build access roads connecting to the existing network. We will work with the local highways authorities to identify routes that minimise the impact on local roads and communities.

We will build new roads, junctions, bridges and underpasses at the same time as the tunnelling work Juxtapose images

Roads to the construction sites
The crossing is split into four construction areas labelled A-D. The following maps show the roads that construction vehicles are likely to use the each of the sites. The exact routes will be carefully planned closer to the time.

(Click on an arrow below the map to view all the maps)

Areas A and B South

Area B North

Area C

Area D

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Some local routes will be affected by construction, with some roads temporarily closed and others having temporary diversions, traffic lights and/or lane restrictions. We will provide advance warning so people can look at alternative routes or travel arrangements.

The predicted impacts on specific roads are classified as follows:

• High: road may close, with possible diversion and/or lane restrictions.
• Medium: road remains open, with temporary diversion, traffic lights and/or lane restrictions.
• Low: road remains open, with temporary diversion, traffic lights and/ or lane restrictions.

Our construction sites will be operated to the highest standards in the industry

Each construction site will have temporary buildings and storage areas, and will include offices, space for equipment and materials, parking and staff facilities. Some sites will include specialist zones, such as the tunnel construction area at the north entrance site. The five main sites are shown on this map, and there will also be several smaller sites.

(Click on the map to reveal the construction sites)

We will make sure we protect species and habitats

We are already carrying out extensive surveys, monitoring and investigations, which are helping us to understand how the crossing might affect air quality, noise and the landscape. This information is helping us to find ways to reduce these impacts. Once all that information has been fully assessed, we will publish the findings in our Environmental Statement, as part of our DCO application.

We will produce a draft Code of Construction Practice (CoCP), which we will submit with our DCO application. It will describe how we will reduce the disruption to local communities and the environment during construction and our approach to limiting noise and vibration.

Surveys will help us understand how the crossing might affect air quality, noise and the landscape

As we develop the CoCP we will work closely with specialists in the local authorities to make sure that it best reflects the needs of their local communities

We will excavate a significant amount of material, which will be processed and reused onsite where possible. Material that cannot be reused, such as hazardous waste and contaminated soil, will be safely disposed of in line with regulations. If practical, we will transport some material that cannot be reused by river rather than by road. We are currently looking at how this might be possible. If we use the river, we may need to build a new temporary jetty or use an existing one.

To reduce construction traffic using the roads, we are considering alternatives, such as river transport, to move materials and waste to and from work sites

As with any road project, we will make sure we protect species and habitats in the area. These include great crested newt breeding ponds, reptile hibernation areas and bat breeding roosts. We will only remove vegetation during the bird breeding seasons (typically early March to late August) if absolutely necessary, and this will be overseen by an appropriately qualified ecologist.

Gas pipelines and other utilities

National Grid is the owner and operator of the transmission networks and it is they who will carry out this work.

Here are the proposed locations for overhead lines and pylons diversions, shown on the map below.

(Click on the map to reveal the locations)

There are other pylons and high voltage overhead lines, owned and operated by UK Power Networks, which will need to be diverted. The designs for these are being developed but the works involved will not be as large scale.

Have your say

To comment on changes to utilities and pylons, answer question 12 in the response form.

Gas pipelines and other utilites

National Grid has carried out onsite inspections and surveys to mark the precise routes where it needs to divert two existing gas pipelines. These are at the A2 and Claylane Wood. It has identified some preferred options.

Designs for the diversion of other pipelines carrying gas and water, and also electricity and telecoms cables, are being developed. We are working closely with the various energy, water and telecoms companies to agree how these works will be carried out.

Find out more

To find out more about utilities, pylons and gas pipelines see the Approach to Design, Construction and Operation

Private finance gives us far more certainty in terms of cost and timeframes, and makes it more affordable as payment can be deferred until the crossing is open, and spread out over 25-30 years. However, given the scale of spend and the capacity of the private finance market, this option is not considered to be an efficient way to pay for the tunnel.

As with any transport project of this kind, its value for money is assessed on how much benefit it would provide, against its cost. This is called a Benefit Cost Ratio (BCR), and it assesses how much benefit a project would provide per unit of cost. A BCR of more than 1 shows that a project delivers more value than its cost. For example, a BCR of 1.5 shows that for every pound spent a project will bring £1.50 in benefits.

The Department for Transport uses six value for money categories ranging from Very High to Very Poor. The Lower Thames Crossing is currently showing Medium value for money with an estimated BCR between 1.5 and 2, which means that every pound spent is expected to bring between £1.50 and £2 in benefits.

We are working hard to make sure that every penny is spent wisely. The government holds us to account to make sure the public money we spend will provide genuine benefits. The most significant financial benefits for road users and businesses will be journey time savings and better connections.

The most significant financial benefits for road users and businesses will be journey time savings and better connections