Sydney trains have been crippled by delays after a maintenance vehicle derailed between Wynyard and Circular Quay.

The delays affect the T2 Inner West and Leppington, T3 Bankstown and T8 Airport and South lines – in other words, the city circle.

A limited number of replacement buses are running between Wynyard and Circular Quay. Commuters are also being told to consider taking the light rail within the CBD.

Sydney Trains has advised passengers to allow extra time when commuting through the city. Some passengers have complained of a delays of over an hour.

Sydney Trains has confirmed that no workers were injured in the incident.

Commuters took to Twitter to vent about Shitney Trains:

Image: Twitter / @TrainsInfo | AAP / Steven Saphore