Closures at the A11 Fiveways roundabout, to allow for major reconstruction work, will be starting tonight.
The roundabout, which links Newmarket to Mildenhall, Thetford, Brandon, Norwich and many villages, will be closed in sections over three weekends to complete the dualling of the carriageway between the M11 and Norwich.
The first phase starts tonight at 10pm with the northbound closure of the A11 and exit/entrance of the A1101 to Mildenhall. The road will reopen at 6am on Monday.
Between 10pm on Friday, October 11, and 6am on Monday, October 14, there will be northbound closure of the A11 and the exit/entrance of the A1065 Brandon Road.
Southbound closure of the A11 and exit/entrance of the A1101 to Bury St Edmunds will take place from 8pm on Friday, October 18, and 5am on Monday, October 21.
A fourth weekend of October 25 to October 27 will be used, if required.
Highways Agency project manager Geoff Chatfield said: “Work to construct the A11 dualling and improvement scheme is progressing well and as planned. The redesign of the Fiveways roundabout, which includes adding more capacity for road users, is an essential part of the project and will ensure that the roundabout continues to operate well after the dual carriageway opens.
“We have to close sections of the roundabout to give the road workers space to operate in. By doing it over three weekends we avoid the need to close the roundabout entirely, and means we can get the work completed as quickly and as safely as possible.”
He added: “We are committed to keeping disruption to road users to a minimum, so we have carefully planned the work to take place at weekends only, when traffic flows are lower, and outside of the busy school holiday periods.”
Motorists travelling on the A11 between Newmarket and Norwich will be diverted away from the Thetford area, along the A14 and the A140 back to Norwich.
The Highways Agency said diversion routes will be clearly signed.
A list of diversions can be viewed online at www.highways.gov.uk/allfiveways-to-thetford.