The bridge at Michaelstone-y-Fedw will be closed for essential maintenance next week.
Caerphilly county borough council manages the structure, which crosses the border between the Caerphilly and Newport local authority areas.
The bridge will close on Tuesday 2 March for 4 working days and the contractor, Edwards Diving Services Ltd, will post signs warning the travelling public in advance.
Motorists are urged to avoid the area and use alternative routes during the closure.
