Lowood Bridge, north of Tweedbank, is to be closed for five days the week after next, although it will be open from late afternoon and overnight.
The 250-year-old bridge, between Galashiels and Melrose on the B6374 road, will be shut from Monday, July 17, to Friday, July 21, from 9am to 4pm daily.
Those closures are needed to allow investigatory work to be carried out ahead of repairs and strengthening works scheduled to be carried out on the grade-B listed crossing later in the summer or early in the autumn.
Diversions will be in place, with the alternative route being via the A6091, the A7 through Galashiels and the B6374.
The upcoming £640,000 revamp of the bridge is due to be completed next financial year.
It is part of a programme of bridge repairs also including improvements to Clackmae Bridge near Earlston, Bowanhill Bridge near Teviothead and Bowden Church Bridge, midway between Midlem and Newtown.
Scottish Borders Council’s executive member for roads and infrastructure, selkirkshire councillor Gordon Edgar, said: “The council has made an effort to minimise the impact of this essential closure of Lowood Bridge by restricting it to the daytime and scheduling it to take place during school holidays when roads are quieter.
“The investment in Lowood Bridge, alongside a number of other bridges in the Borders, will ensure these vital structures can continue to be used for years to come.”
Lowood Bridge is currently subject to a 26-tonne precautionary weight limit.