A concrete retainer wall collapsed onto Sydney train tracks after the city has been inundated by a week of wet weather.
The wall collapsed at about 6pm on Sunday in a landslide that blocked the tracks at Harris Park Railway Station.
Residents reported hearing a loud boom at the time of the landslide and wall collapse but no commuters were on the platform at the time and there were no trains at the station. No-one was injured.
Clean-up crews say it will take a week to clear the tracks, meaning train delays are expected for at least the coming work week.
Investigators say it is unusual the support wall would have collapsed in the wet weather conditions and are intended to quality review other parts of the retainer wall.
This video explains how the wet weather may have caused the landslide that collapsed the wall.