A £450,000 project to replace expansion joints on a motorway bridge in Perthshire will begin next month.
The Earn Bridge carries the M90 over the River Earn east of Bridge of Earn between Perth and Edinburgh.
Roads bosses say the expansion joints are essential for safety, with some sections of the bridge moving by up to 10cm during changes in temperature between the summer and winter months.
The first phase of the work begins on the southbound carriageway on August 5 and will last for two weeks.
Contractors have scheduled a break in the programme to accommodate local events such as the Solheim Cup at Gleneagles and the Blair Horse Trials, which are expected to draw huge crowds to Perth and Kinross.
The works will then restart northbound on September 30 for a further fortnight.
The M90 will remain open throughout, but a contraflow will be put in place.
Bear Scotland said road users should prepare for delays and plan ahead.
The firm said: “Traffic modelling software has indicated that the project will increase the average journey time through the works by around 15 minutes at peak times during the day.
“However, as we approach the busy summer periods, these times may be extended depending on traffic flows in the area.”
Andy Thompson, Bear Scotland’s north east representative, said: “This £450,000 bridge improvement project will allow our teams to carry out the replacement of expansion joints on the M90 Earn Bridge, ensuring the bridge continues to operate safely.
“We’ve designed the project across two phases to ensure that there is minimal impact to road users attending the Solheim Cup at Gleneagles or other major events in the area, with the project arranged so all traffic management will be removed from the road mid-August to the end of September.
“The traffic management is essential for ensuring the safety of our work force as well as motorists, and our teams will do all they can to carry out the work as quickly and safely as possible. We advise road users to abide by all traffic or speed restrictions put in place during the work for their safety, and to use both lanes when queuing to help reduce congestion.
“We thank road users for their patience during these essential works and encourage them to plan their journeys in advance by checking the Traffic Scotland website before they travel and allowing some extra time to reach their destination.”