The delays are scheduled to affect travel from ten days from early Friday morning.
They come after a problem with the steering mechanism of one of Zurich’s Cobra trams was identified while it was in the depot.
In a statement, the Zurich VBZ transport authority said in the worst-case scenario, the problem could lead to the trams derailing.
Now, as a safety precaution, all of the city’s 88 Cobra trams will now checked.
During the inspection process, the Cobra trams will also be forced to drive more slowly than usual. Their maximum speed will be reduced from 60kph to 42kph. At crossings and switch points, the maximum speed will be 12kph.
The VBZ said it was aware this would lead to longer journey times, delays and missed connections.
Tram lines 2, 3, 4, 5, 6, 13 and 17 will be directly affected by the reduced speeds as theses lines are serviced by Cobras.
Lines 7, 10, 11, 12 and 14 will see fewer low-floor trams running than usual.
Tram lines 8, 9, 10, 12 and 15 will not be affected.
The full impact of the inspection works is not yet known.