Derbyshire County Council is warning motorists about changes to traffic flows while work connected to improving a footpath opposite a Chesterfield leisure park continues.
From today, vehicles will be unable to turn right off the A61 into the town's Alma Leisure Park.
Instead they will need to continue to the north then loop back via Horns Bridge roundabout before turning left into the park's entrance.
This work to widen the footpath and realign the forecourt outside the St John Ambulance Station on Derby Road is expected to continue until Friday, March 2.
A council spokesman said: "The improvements will be done outside of peak commuter times between 9.30am and 3.30pm when northbound traffic will be reduced to a single lane.
"Outside of these times, traffic will be restored to two lanes both north and southbound, although the no right turn will remain.
"Traffic travelling south and turning left out of the leisure park will remain unaffected.
"This latest round of work is part of wider improvements for pedestrians and cyclists on this stretch of the A61 and is aimed at easing congestion and improving safety."