Drivers using the A11 to get in and out of Norfolk will face diversions when the Fiveways roundabout at Mildenhall is closed.
Highways England is making improvements to the A11, including road signs, traffic lights, traffic sensing loops and changes to make it safer.
The work, which is under way, means lane closures are in place on the Fiveways roundabout at Mildenhall between 8pm and 6am on weeknights until Thursday, November 15.
But drivers have been warned there will be a total closure of the roundabout and its approaches on Friday, November 16, between 8pm and 6am.
Highways England says a clearly signed northbound diversion for the A11 will be in place via the A14 and A134 before re-joining the A11 at Thetford.
And the southbound diversion for the A11 will be in place via the Elveden Road, A134 and A14 before re-joining the A11 at junction 38.
Meanwhile, work to clear vegetation and stabilise the westbound slope on the A47 at Guyhirn has begun. That work will take about nine weeks, but no diversion is needed.
However, a 40mph speed restriction is in place.
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