OC Transpo still can't say what's causing the leaks plaguing LRT stations

The corrosion found behind ceiling tiles over the last week was only the latest issue with the aging St-Laurent tunnel, but inspectors could not have found the problem while repairing fallen concrete in January — because they never looked for it. 

OC Transpo still can't say what's causing the leaks plaguing LRT stations
inside of a station with the top of a train visible

The corrosion found behind ceiling tiles over the last week was only the latest issue with the aging St-Laurent tunnel, but inspectors could not have found the problem while repairing fallen concrete in January — because they never looked for it.