There are calls for an investigation after the third fire on a Sydney tram in a week caused headaches for the morning commute.

The small fire on the tram’s roof forced services to be suspended for several hours on Thursday as the private operator assessed the risk to its fleet.

A tram network holds a city together, conferring a conceptual cohesion that is itself welcoming, which makes the mid-century rush to rip them out across cities worldwide all the more baffling.

Sydney light rail commuters have had their travel plans thrown into chaos after a tram caught on fire in the city’s inner suburbs.