The problems facing the building of the Lower Thames Crossing are accelerating after it was revealed the tunnel will create five million tonnes of environmentally damaging carbon dioxide.

The 14-miles route - due to link east of Gravesend with Essex in a bid to relieve congestion at the Dartford Crossing - has already seen costs soar by more than 50% to a staggering £8.2bn, from its original estimate of £5.3bn. That makes it more expensive, mile-per-mile, than the HS2 project.

Just days earlier, Highways England had pulled a planning application for the project in order to address "specific points" raised by the Planning Inspectorate.

But now its environmental impact is hitting the headlines too.

According to a report from the BBC, the tunnel will create 2m tonnes of CO2 during the building phases, with traffic expected to generate a further 3.2m tonnes over 60 years.

And that, campaigners say, makes a mockery of the government's much trumpeted green agenda.

Speaking to the BBC, Chris Todd, from green group Transport Action Network, said: “If the government is serious about tackling climate change, it can't keep ignoring the emissions roads are causing.

“We welcome greater ambition from the PM on the international stage, but it’s very easy to make announcements without taking action – and right now transport policy is making a mockery of his promises.”

A spokesman for the Thames Crossing Action Group, which opposes the project, said: "Thames Crossing Action Group are pleased that Highways England have finally had to provide this important information.

"We and others have been trying to obtain this, and various other important info/details, and HE have constantly been withholding such info.

"Their lack of ability to provide adequate info to the Planning Inspectorate for their LTC DCO application is the reason they had to withdraw the application, rather than the Planning Inspectorate refusing it, which was due to happen.

"There is so much important info that people need and deserve to review, and should have been shared during the consultation period to allow meaningful responses to be made.

"How are people supposed to have been able to comment on the environmental impact and mitigation of LTC, as we were asked to do in the consultation, when info like this had until now been withheld?

"From our experience of dealing with HE we also have to wonder if these figures are a true representation of what should be expected if the LTC goes ahead, or if as we suspect it would be worse than they are predicting.

"We don't believe HE will be taking certain aspects which will be a direct result of LTC into account when predicting these figures.

"Things like the carbon emissions associated with the Blue Bell Hill improvements – if they go ahead – and the Tilbury Link Road and Rest and Service Area – both of which have been 'removed' from the LTC to be progressed as separate stand-alone projects despite the fact they are needed due to LTC as [they] were previously part of the LTC project. False economy both on environmental impact and also economic impact.

"We would also remind those questioning whether this will be balanced out by traffic not sitting at the Dartford Crossing, that not only are these figures huge amounts of carbon, but also that the Dartford Crossing is still going to be over capacity even if LTC goes ahead. LTC is not going to solve those problems.

"At a time when many are quite rightly very concerned about negative impacts on the environment, and our lives and health; and when the

government are saying they are serious about tackling environmental issues, with COP26 (26th UN Climate Change Conference of the Parties) being hosted in the UK, it is time for actions to back the announcements, and that means putting the brakes on with regard to the proposed Lower Thames Crossing, and other environmentally harmful projects.

"It would be bad enough to consider the huge negative and destructive impact the LTC will have, if it solved the problems we all suffer with due to the Dartford Crossing, but the fact is that the LTC is not fit for purpose and will not solve those problems. We deserve better."

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