Lower Thames Crossing: Digging Up the Truth

When publicly funded infrastructure projects grow to a multi-billion-pound scale, transparency should grow with them. Instead, the £11 billion Lower Thames Crossing (LTC) has become a textbook example of government secrecy. For years, campaigners and local communities have been asking a simple, fundamental question: is this massive, destructive £11 billion Smart Motorway actually worth it?

The answer should be found within the LTC’s business case, a vital document detailing the project’s financial viability, costs, and projected value for money. When the National Audit Office let slip in a letter to Transport Action Network (TAN) that an Outline Business Case (OBC) had been produced when the decision had been taken to seek private finance, we requested the Department for Transport (DfT) publish the document under the Environmental Information Regulations 2004 (EIRs). What followed was a frustrating journey of official evasion and a blatant cover-up eventually exposed by the government’s own records.

The Request: Demanding the Business Case

Without the business case, the public is blind to the economic justifications of a project subsidised by at least £3.1 billion of public funds—assets that will eventually be privatised alongside the Dartford Crossings. The DfT refused to publish the OBC, relying on an exemption under Regulation 12(4)(d) of the EIRs, claiming the information was still “draft”, also that revealing it would “adversely affect the confidentiality of commercial information.” Meanwhile, TAN’s appeal of this refusal has been met with months of silence with DfT breaking statutory deadlines.

The Smoking Gun: A Paper Trail of Lies

“We cannot show you the business case because it is incomplete.” This was the DfT’s simple excuse. It sounded plausible, but it was completely untrue. The breakthrough came from the National Infrastructure and Service Transformation Authority (NISTA), a new government body overseeing major projects.

When NISTA published its 2026 annual report, the truth spilled out. Tucked away in official records was the revelation that the Lower Thames Crossing’s Outline Business Case had already been formally approved in October 2025.

This single date shatters the DfT’s entire defense. The business case was not an unfinished “draft”; it was a finalised, signed-off document approved at the highest levels back in October 2025. The DfT lied to protect itself from scrutiny, hiding a document while claiming it did not exist in a disclosable format.

£3.1 Billion and Counting: The True Cost of Secrecy

This lack of institutional honesty is deeply alarming, especially when we look at the immense scale of public funds involved.

To date, at least £3.1 billion of public money has already been committed or spent on the Lower Thames Crossing which will be privatised along with the Dartford Crossings in 2028. We also recently exposed how the DfT has been secretly allocating more money towards this controversial project. It is astonishing when you stop to think about it. Billions of pounds of taxpayers’ money has been locked into a project, which will be gifted to the private sector along with the Dartford Crossings, with the loss of billions of pounds in future toll revenues. Yet there is absolutely no transparency regarding this transference of national assets into private hands, nor the staggering financial risks involved.

National Highways estimates the total cost of the LTC will exceed £11 billion. It will involve building the largest bored road tunnels in the UK and 12 miles of Smart Motorway. In an era of tightly constrained public finances, committing over £3.1 billion without allowing independent economic scrutiny is a massive democratic failure.

Transport Action Network has already persuaded the National Audit Office to investigate the LTC. Although this investigation is very welcome, we still don’t have a date for when this will start. In the meantime, the OBC should be published immediately.

Why the Cover-Up Matters

Why the cover-up from the DfT? Likely because the numbers don’t add up. Independent economists warn that mega-road projects suffer from optimism bias and understated costs. If the business case showed a strong return, the government would be shouting it from the rooftops. Their effort to hide the data suggests the LTC’s value for money is incredibly weak.

The Fight for Transparency Continues

Democracy functions on the fundamental principle that the public has a right to see the evidence underlying monumental spending decisions

TAN refuses to accept this state-sponsored gaslighting. We are challenging the DfT’s unlawful non-disclosure and will escalate to the Information Commissioner’s Office if necessary. The government cannot spend £3.1 billion of our money on a climate-wrecking Smart Motorway while hiding the paperwork. It is time for the DfT to end the deception and release the Lower Thames Crossing’s Outline Business Case immediately. Public funds should serve the public good, and we have a right to know how our money is spent.