The fates of three multi-million pound revamp schemes on the A47 in Norfolk now rest with a High Court judge.

Lawyers in a crucial court case, which will determine whether dualling of two sections of the road - plus the revamp of a major junction near Norwich - can go ahead made their final representations on Thursday (May 11).

Plans for the revamp of the Thickthorn roundabout, on the edge of Norwich, and dualling the A47 between Blofield and North Burlingham and Easton to North Tuddenham are at the heart of a legal battle at the Royal Courts of Justice in London.

Eastern Daily Press: The Thickthorn roundaboutThe Thickthorn roundabout (Image: Mike Page)

Lawyers representing climate activist Andrew Boswell, who brought the case to the High Court because of concerns over their environmental impact, told a judge government decisions to allow those schemes to happen were unlawful.

But government lawyers insist the decisions - made by two transport secretaries - were lawful.

High Court judge Mrs Justice Thornton, who has been hearing the case, has reserved judgement.

But if she decides an unlawful decision was made, she could block the schemes from happening or send them back to the drawing board.

And that could have ramifications for road schemes across the county, including the Norwich Western Link.

If Mrs Justice Thornton, who is married to former Labour Party leader Ed Miliband, rejects Dr Boswell's argument, then National Highways can start work on the long-delayed A47 schemes.

Eastern Daily Press: Mrs Justice ThorntonMrs Justice Thornton (Image: Courts and Tribunals Judiciary)

Barrister David Wolfe, KC, acting for former city and county councillor Dr Boswell, told the court hearing - known as a judicial review - that the cumulative carbon impact of all the A47 projects had not been lawfully considered.

He said figures Dr Boswell submitted calculating the cumulative impact of all three schemes had not been taken into account.

Eastern Daily Press: Dr Andrew Boswell at the High Court in LondonDr Andrew Boswell at the High Court in London (Image: Dan Grimmer)

He told the court the government had a statutory duty to consider the cumulative carbon impact of the schemes and to help meet the government's target to reach net zero by 2050.

But he said the secretaries of state had "misdirected" themselves in how they applied the information about what carbon each scheme would produce in terms of construction and traffic and the cumulative impact of that.

Dr Wolfe, who successfully overturned the government's decision to permit a road tunnel near Stonehenge two years ago, said that was "a legal error", which he argues should render the decisions to grant permission unlawful.

But barrister James Strachan, KC, representing the government, said: "There is no basis for Dr Wolfe to characterise it as an error of law. It was not."

He said the cumulative impact of the Norfolk schemes had been considered, identifying their percentage impact on the national carbon budget.

At Thursday's hearing, Mr Strachan said: "It boils down to the way that the cumulative carbon assessments have been assessed was not the way the applicant would do it. So what?"

He said the transport secretary had used "careful consideration" and "evaluative judgement" over what the impact of all projects would be on a national, not local, scale.

Lawyers for National Highways - the government company responsible for major A-roads - also defended the assessment approach which was taken. 

Eastern Daily Press: The A47 between Easton and North TuddenhamThe A47 between Easton and North Tuddenham (Image: National Highways)

The challenge has meant National Highways has not been able to begin construction at the three locations.

Mrs Justice Thornton's verdict on whether the decisions were lawful or not is likely to be some weeks or months away.

The plans for Thickthorn include a new slip road off the A11 northbound, which will take motorists beneath both roads before re-joining traffic on the A47 heading towards Great Yarmouth - eliminating the need to use the roundabout.

Just over 1.6 miles of the road between Blofield and North Burlingham - considered a crash blackspot by police - are due to be dualled.

And five-and-a-half miles of the road between Easton and North Tuddenham are also due to be dualled.