The Durham Street Bridge in Walkerton will be fully closed overnight tonight.
The bridge will close at 10 pm tonight, and is expected to reopen at 4 am Tuesday morning.
Drivers and pedestrians are asked to use alternate routes, and to be patient as the contractor works to complete crucial repairs to the bridge.
The closure is needed to shift the alternating lanes from the south side of the bridge to the north side.
Once the closure ends, the bridge will return to alternating traffic with a single lane closure using temporary traffic lights.