The design of a multi-million pound revamp of a roundabout on the edge of Norwich has been altered to ensure two burial mounds dating back thousands of years are not damaged.

Proposals for changes at Thickthorn Interchange, where the A47 and A11 meet on the edge of Norwich, were lodged at the end of March.

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

But, at a public hearing into the application by National Highways on Wednesday (November 17), a planning inspector asked how the scheme would ensure two Bronze Age barrows, known as tumuli, were not affected.

Those barrows, in Cantley Wood, are a scheduled monument. One is a fern-covered bowl barrow, measuring 30 metres in diameter and just over two metres high, while the other is a tree covered barrow, 25 metres in diameter and two metres high.

They are a nationally important site, as evidence of Bronze Age funerary practice is extremely rare and the barrows are undisturbed.

Planning inspector Matthew Shrigley, at the virtual hearing, queried how the project could affect the mounds.

Officers from National Highways said the archaeological significance of the barrows would be preserved, with no physical impact to either monument.

They said the scheme was altered to place the road as far as possible from the mounds.

Paul Bennett, from National Highways said, once the scheme is complete, a new interpretation board could be included at the site of the barrows.

The changes at the junction would also see a segregated left-hand turn added to those travelling eastbound on the A47, a new footbridge and a fourth lane on the southern part of the junction.

Norfolk County Council raised issues about the classification of mooted new link from Cantley Lane South to the B1172, via a bridge over the A11.

The county council fears making it a B-road would encourage more traffic to use it.

David Cumming, the county council's strategic transport team manager, said: "Cantley Lane is a minor country lane and we have had concerns expressed to us by local residents and the parish council that traffic could be driven on to Cantley Lane and the new link road.

"We don't expect that to be a significant impact of the scheme, but if it was classified as a new B road, that would indicate to motorists and satnav systems that it is part of a more major road network.

"We feel that classifying it as a B road would, in itself, start to attract traffic to it. We feel a lower classification is a better designation of that road."

National Highways officers told the inspector discussions with the council over designation would continue.

The inspector also heard how the county council was concerned that the 'arm' of the scheme leading from Norwich to the A11 would be the "worst performing" section of the scheme.

Ben Williams, from National Highways, said that, between April 2012 and March 2017, there had been 39 crashes at the junction, three serious and 36 involved slight injuries.

The crashes resulted in 54 casualties and involved 72 vehicles.

He said: "Improving the junction would improve the current levels of congestion, reduce the number of accidents and allow for economic growth in the area."

The scheme will see the complete removal of 17 individual trees and 11 groups of trees. Two of those removed would be veteran trees, which form rich habitats for insects.

The Woodland Trust has objected to their removal, but National Highways officers say the logs from the veteran trees would be placed nearby and there would also be replanting.

The Planning Inspectorate will consider whether to grant permission, with the public hearings - and written submissions - part of that process.

Following the hearings, Mr Shrigley will make a recommendation to transport secretary Grant Shapps, who gets the final say on whether the scheme should get a development consent order.

If it gets the go-ahead, work would start in 2023 and be finished in 2024.

Similar hearings have recently been held over the dualling of sections of the A47 between North Tuddenham and Easton and from Blofield to North Burlingham.

Another hearing is scheduled for Thursday. Tuesday's hearing ended after 15 minutes because nobody turned up to speak at it.

What is a barrow?

Round barrows, according to Historic England, are funerary monuments dating from the Late Neolithic period to the Late Bronze Age.

Most examples belong to the period 2400 to 1500 BC.

The earthen mounds, also known as tumuli, are sometimes surrounded by ditches and covered single or multiple burials.

More than 10,000 surviving examples have been recorded across Britain, including some 2,000 in Norfolk, but many more have been destroyed.

Often occupying prominent locations, Historic England says they are a major historic element in the modern landscape.

They vary considerably in form, and provide important information on the different beliefs and social organisations among early prehistoric communities.

Among the most famous barrows in England are the Anglo Saxon ones at Sutton Hoo, in Suffolk.

Dating from the 6th or 7th Centuries AD, they are much later than those in Cantley Wood.