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Highways England digs deep to prepare improvement to vital East Anglia junction



Preparatory work starts for the A47 – A11 Thickthorn Interchange upgrade.


Plans to improve a vital East Anglia junction have taken a step forward with the recent start of preparatory works to help inform the upgrade, which is due to start in 2023.


Highways England is improving the A47 in six places between Peterborough and Great Yarmouth as part of a £450 million-plus investment, including the Thickthorn Interchange with the A11 at Norwich.


Ground investigation work has started, with five holes being gradually drilled up to 120 feet deep to help the project team understand the existing rock and soil types, and therefore inform their work to improve the junction.


Once complete by 2024, the upgraded junction will improve journey times by between four and five minutes for the 53,000 drivers who use the roundabout daily, while also making the junction safer by reducing the number of accidents there.


Highways England programme lead for the A47 Chris Griffin said:


"The Thickthorn Interchange connects the A11 to the A47, enabling the growing economic activity around Norwich. The current junction can act as a bottleneck who use the roundabout daily, causing queues and slowing journeys. Our improvements to enlarge the roundabout and provide dedicated free-flow links will reduce delays at the junction, ensuring smoother and safer journeys."


The work will see a 17-foot long drill being used to gain a better understanding of the ground conditions, which is vital before work can start on the upgrade. Noisy work will only take place during the day, with Cantley Lane South currently closed from the A47 to the railway bridge until Friday 9 July with a clearly signed diversion route in place. One lane is currently closed on the A11 approaching Thickthorn from 8pm to 5.30am on weekdays (opening on Saturday 26 June). Further survey work will continue until October, although no further closures are planned.


The teams will be drilling around 30 foot a day, looking at what lays beneath the road surface. Up to a metre down into the ground of the area is man-made, with the project team needing to understand what types of soil, rock, and groundwater are in the area so they can build the roundabout upgrade swiftly and efficiently.


Highways England announced its preferred option for upgrading the Thickthorn junction in August 2017. Since then, plans have been refined based on feedback from the consultation, with the latest designs shared with road users a year ago.


Latest changes see the previously proposed A47 westbound to A11 southbound free-flow link road replaced with a dedicated free-flow left turn lane at the roundabout, reducing the environmental impact of the proposed scheme whilst still improving journey times. Traffic lights will be installed on the B1172 arm of the Thickthorn roundabout, while a fourth lane will be added to the southern half of the roundabout. The B1172 will also have a reduced speed limit of 40mph between the junction and Hethersett, improving safety. Existing junctions to and from Cantley Lane South to the A11 and A47 will be closed, and replaced with better, safer access via a bridge over the A11 to the B1172.


A footbridge for pedestrians, cyclists and horses has moved closer to its original position, reducing the journey time and providing a safe dedicated crossing of the A47 for those users. The option selected will see a new, free-flowing link road created for drivers heading from the northbound A11 to the eastbound A47. The link road will allow drivers to avoid using the roundabout, which itself will be freed up for drivers making other turns at the junction.


The Thickthorn upgrade is one of six projects that Highways England is doing to improve the A47. Three sections of the 115-mile stretch of the A47 between Peterborough and Great Yarmouth will be upgraded to dual carriageway. Norfolk sections will be upgraded between Blofield and North Burlingham and from North Tuddenham to Easton, while in Peterborough the A47 between Wansford and Sutton will also be dualled. There will be further junction improvements at the A141 roundabout in Guyhirn, and at Great Yarmouth junctions.


For more information about this work, please visit our A47 Thickthorn junction web page.

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