The incident, which occurred on White Lane, Gleadless, became inaccessible and forced tram services to be diverted.
Stagecoach Supertram said its blue route services are unable to run between Gleadless Townend and Birley Lane due to the non-tram crash.
Trams are now turning at Birley Lane towards Halfway and Herdings towards Malin Bridge.
Tickets will be accepted on First and Stagecoach buses from Manor Top onwards Halfway.
The police have been contacted for more information.