Campaigners against the Silvertown Tunnel have sent a letter to Sadiq Khan threatening to seek a judicial review of the project if it is approved.
The No to Silvertown Tunnel coalition sent a letter to the mayor last week, saying that modelling from Transport for London (TfL) on the project is “insufficient to make a well-informed decision”.
Judicial reviews involve the courts scrutinising decisions made by a public body.
Campaigners claim that the modelling for the road tunnel – which would run across the Thames from Greenwich to the Royal Docks – shows that congestion would decrease at the tunnel mouth, but increase in surrounding areas.
They say this would increase air pollution.
The letter, seen by City A.M., said: “We very much hope that rather than taking the severe risk of wasting public money moving forward with a scheme that will be very expensive to cancel once the constructors start work, you will instead ask TfL to provide the full analysis that they should have done years ago, and review the scheme on the basis of complete and up-to-date information.”
A spokesperson for the mayor said the tunnel was essential for East London.
They said: “Extensive modelling on the impacts on traffic, air quality and carbon emissions has been undertaken and has been subject to thorough examination in public, as well as rigorous peer review.”
The project is expected to get final approval from TfL within a matter of weeks, after a drawn out battle with anti-tunnel campaigners.
A TfL spokesperson said: “A response to the letter will be issued in due course.
“The Silvertown tunnel scheme was subject to significant scrutiny as part of the development process, including a six-month public enquiry.”