You know that something’s wrong when buses start thrashing up and down the Gaustrasse, shuttling passengers along the route normally served by trams.
Probably “leaves on the track”.
No, wait, that was in England…..
Must have been the “wrong sort of snow”
No, that was England, too….
Mainz Daily Photo 
On occasion, this happens with our commuter train service. Buses are brought in on a parallel route.