The northbound traffic on the Low Level Bridge will be reduced to one lane starting on Wednesday to allow crews to make emergency structural repairs.
A plate that covers one of the bridge joints is loose, a problem the city discovered during a routine inspection.
"It's one of those things where regular inspection pays off where we found something before it became a big problem," said city roadway maintenance director Bob Dunford.
"So it's going to take us a few days to re-anchor that joint cover plate."
Concrete will be poured over the repairs on Friday morning and take three days to cure.
The bridge is expected to be back to normal by Tuesday morning. In the meantime, drivers are advised to use the James MacDonald Bridge, Dawson Bridge or Walterdale Bridge to avoid traffic tie-ups.