Drivers are being warned to expect delays from Monday, when work starts to strengthen a bridge on a busy Warwickshire road.
The improvements to the Cain Bridge on the A435 near Alcester will take place over the next three weeks.
To keep traffic delays to a minimum, the work will be carried out only on weekdays between 0930 and 1530 BST, the Highways Agency said.
Motorists are being advised to use a different route, wherever possible.
Temporary traffic signals will help to control the flow of traffic in both directions.
Anna Gioka, assistant structures sponsor for the Highways Agency, said: "The parapet repairs at Cain, where the A435 passes over the River Arrow, are vital to ensure the safety of vehicles travelling over the bridge on this busy road.
"Limiting traffic signals to off-peak hours will minimise disruption to all road users.
"Motorists are advised to allow extra time or vary their journeys if possible."