Lower Thames Crossing Facts

Core cost - £12 billion (likely)

The LTC would cost £9 billion according to National Highways' submission to the DCO examination [1], making the scheme more expensive per mile than the cancelled HS2 project. However this figure is likely to be a huge underestimate as it dates from 2020 when the outline business case was produced. The Infrastructure and Projects Authority (IPA) in their Analysis of the National Infrastructure and Construction Pipeline 2023 [2] reported that construction materials costs had increased by 40% since 2020.

In March 2025, the government approved the M3 J9 scheme with a cost of £290m [3]. Yet National Highways had told the public examination that the cost would be £215m and accounted for risk and inflation [4]. This represents a rise in costs of 35% in just two years, showing National Highways either deliberately hid the true costs of the scheme or was incompetent. (There were no legal challenges).

If this increase is applied to the LTC's even older figures (dating from 2020), then the scheme’s core cost rises to over £12bn. TAN believes this is a truer reflection of the likely costs.

Sources

[1] Funding Statement, 2.1.1, National Highways, October 2022

[2] Analysis of the National Infrastructure and Construction Pipeline 2023, Infrastructure and Projects Authority, February 2024

[3] Government press release, 13 March 2025, announcing approval of £290m, M3 J9 expansion scheme.

[4] National Highways’ funding statement submitted to the M3 J9 Examination, dated November 2022 states: “The Scheme has a most-likely estimate of £215 million, including allowances for risk and inflation at the date of application. This estimate includes all costs to deliver the Scheme from Options stages through to the opening for traffic.”

Costs likely to increase by £4bn as scheme incomplete

The overall cost of the LTC is likely to increase by an additional £4bn as necessary supporting road upgrades have been removed, or not included, to reduce the scheme’s cost and artificially inflate the already low Benefit Cost Ratio (BCR). These include:

Tilbury Link Road [5]
A229 Blue Bell Hill scheme [6]
A13 Orsett Cock and Manorway junctions
East facing slips on A13 to Lakeside
Wider local road network upgrades to cope with the extra traffic

In addition, Kent County Council is calling for the entire A2/M2 to be widened to cope with the LTC [7]. Similarly, it is likely that the M25 north east quadrant would need widening.

Taking all these things together, the scheme’s total cost = £12bn + £4bn = £16bn

Sources

[5] https://www.thamescrossingactiongroup.com/tilbury-link-road/

[6] https://www.thamescrossingactiongroup.com/blue-bell-hill-improvements-consultation-response/

[7] Kent County Council letter, dated 13 March, 2025, submitted to post examination consultation on funding for the LTC (see page 2).

Low value for money

The Benefit Cost Ratio (BCR) is just 0.48, meaning that for every £1 spent only 48p is returned to the economy. The adjusted BCR, inflated by including ‘wider economic benefits’, agglomeration etc (with little supporting evidence), is just 1.22 [8]. This puts the LTC in the DfT’s Low value for money category [9]. It is a myth that the LTC is vital for the UK economy. The project would be a drain on the economy and would swallow up limited funds for transport, meaning better value and more sustainable projects cannot go ahead.

Sources

[8] Combined Modelling and Appraisal Report,Table 7.17, National Highways, October 2022

[9] DfT’s Value for Money Framework, Box 5.1, Department for Transport, 2015

LTC would not relieve congestion long term

Using traffic modelling data provided by National Highways, Thurrock Council have reached the conclusion that the LTC would take as little as 4% of traffic away from the Dartford Crossing [10]. They also concluded that the Dartford Crossing would be back to today’s level of traffic within 5 years of the LTC opening, if it goes ahead [11]. Instead the LTC would massively increase traffic on the roads in Thurrock and Gravesham, with inadequate infrastructure to allow traffic to migrate between the crossings if any incidents occur [12].

Sources

[10] https://www.thamescrossingactiongroup.com/ltc-not-fit-for-purpose/

[11] https://www.echo-news.co.uk/news/24069270.lower-thames-crossing-will-relieve-congestion-five-years/

[12] https://www.thamescrossingactiongroup.com/incidents-ltc-dartford-crossing/

Carbon emissions

The total carbon emissions caused by the LTC are 6.6 million tonnes over the project’s lifetime [13]. The construction emissions amount to 1.763 million tonnes [14], and the operational emissions from the extra traffic total 4,833,762 tonnes [15].

Sources

[13] Environmental Statement - Climate Chapter 15, 5.6.19, National Highways, October 2022

[14] Environmental Statement - Climate Chapter 15, 15.6.2, National Highways, October 2022

[15] Environmental Statement - Climate Chapter 15, Table 15.16, National Highways, October 2022

Lack of consideration of non-road alternatives

National Highways’ evidence to the examination reported that the last - and only - time non-road alternatives were considered was sixteen years ago, in 2009 [16]. A rail link was briefly considered then, but immediately dismissed. Since then only various road options have been considered despite the dramatically changed climate, and the need to increase opportunities and boost the economy.

That's we commissioned Jonathan Roberts to look at high capacity alternatives to a road-based lower Thames Crossing. His report, the Roberts Report [17], looked at the success of Transport for London in generating cross-river traffic and local population densities to show it would be possible to generate significant passenger journeys in the Dartford area with a new heavy rail link. He also explored the impact of modest infrastructure improvements to enhance rail freight opportunities.

This formed the basis of our report: Essex-Kent Superlinks [18], that sets out how for £2-2.5bn (a fraction of the cost of the LTC) you could:

generate 50 - 100 million passenger journeys annually with a new cross-river rail link at Dartford
remove 550,000 - 1,100,000 HGVs off our roads every year
create safer roads with less traffic and HGVs, reducing the pressures on emergency services and the NHS
increase opportunities for 220,000 households that won't benefit from the LTC

The measures set out in this report would better deliver on Labour's missions on boosting the economy, safer streets, increasing opportunities and decarbonisation. Additional measures should also be explored, including the proposed Thames Gateway Tramlink by KenEx and restoring or creating new ferry services and better bus links.

Sources

[16] Statement of Reasons, 5.13.4, National Highways, October 2022

[17] High capacity alternatives to a road-based lower Thames Crossing, Jonathan Roberts Consulting (the Roberts Report), 26 February, 2025

[18] Essex-Kent Superlinks, Transport Action Network, February 2025

**LTC would increase collisions**

The DCO planning application showed that National Highways calculate that the LTC would actually increase collisions, causing 26 more fatalities, 182 serious injuries, and 2,464 slight injuries - over the 60 year appraisal period [19]. It is the only major road scheme to make safety worse.

It is also worth noting that National Highways' modelling did not consider induced demand for lorries, so these figures are likely to be an underestimate.

Sources

[19] Combined Modelling and Appraisal Report, Table 7.7, National Highways, October 2022

**LTC would worsen air quality**

National Highways' Appraisal Summary Table Report states there would be an increase in air pollution: 89,786 tonnes of NO2 over the 60 year appraisal period, and 64,450 tonnes of PM2.5 [20].

Sources

[20] Appraisal Summary Table Report, page 7, National Highways, October 2022

Biodiversity and landscape impacts

The LTC would directly harm some of our most important habitats and landscapes such as the Thames Estuary Marshes Special Protection Area (SPA) and Ramsar site. It would also cross the Kent Downs National Landscape (formally Area of Outstanding Natural Beauty, or AONB). It would also destroy 5.35ha of irreplaceable ancient woodland, including the newly designated The Wilderness ancient woodland, and the Woodland Trust owned Shorne and Ashenbank Woods SSSI.

LTC DCO planning application

Much has been made about the length of the DCO planning application for the LTC, with it being used as an excuse to push planning reforms that would cut environmental protections and democratic participation. Some have claimed the planning application totalled 2,383 documents and 359,000 pages. This myth originated from a roads lobby group called Britain Remade, but has been repeated - unchecked - by mainstream media, including in the Times, FT, and politicians.

The planning application (DCO application) was actually 554 documents (not 2,383 claimed) [21]. Britain Remade had misleadingly included all the evidence submitted to the 6-month long examination, including many duplications and rebuttals of evidence. They did not count the documents in the actual planning application itself.

TAN has fact checked the number of pages in the DCO planning application, and has discovered that Britain Remade exaggerated the page total sixfold. The DCO planning application is actually 63,330 pages long, not the 359,000 claimed. You can see our figures here, and more detail on our LTC Myths and Facts page.

However it is not surprising the planning application for this project is large. It is the longest, most ambitious and costly road scheme ever proposed. It is 23 kilometres long and impacts on internationally important habits, national landscapes, and ancient woodland. It increases deaths and injuries, air pollution and carbon emissions. It would cost the country around £16 billion all told, while having an extremely weak business case.

Sources

[21] The full DCO planning application documents can be viewed here on the Planning Inspectorate website

Throwing good money after bad

Claims have also been made that £800 million has been spent on the LTC planning application. Unfortunately this, once again, is false. In fact, freedom of information requests [22] have revealed that this £800m cost included other significant expenditure, not just the two planning applications. The biggest costs so far are for technical surveys and investigations - £307.4m (+VAT which brings the total to £368.88m). These costs are non-recoverable and known as "sunk costs", so will not be added to the final bill for the LTC, skewing its poor BCR. These huge costs are unsurprising for the UK’s longest road tunnel, going deep under the Thames plus 13km of new motorway standard road. The £800m spent to date also includes land and property purchase costs (£97.9 million + VAT) as many have been intimidated out of their homes despite the project’s uncertainty. The planning applications cost £245.3m (+ VAT), up to February 2023, and the many consultations are a tiny part of the costs so far (£27m, or just under 4% of the money spent).

Sources

[22] Freedom of Information response from National Highways, 27 March 2024

The LTC is a Smart Motorway by stealth

The LTC is being designed to Smart Motorway standards (3 lanes, no hard shoulder). National Highways deny it is a Smart Motorway, but it is in all but name having the same technology, the same refuges, 3 lanes wide, with no hard shoulder [23].

Source

[23] https://www.thamescrossingactiongroup.com/ltc-smart-motorway/