Boy charged after allegedly throwing seat from moving train onto Sydney road

A 14-year-old boy has been charged after allegedly throwing part of a seat from a moving train onto a busy Sydney road.

Police launched an investigation after a video was posted on Facebook depicting a boy tossing a seat through the open doors of a train onto Mona Vale Road, as the locomotive crossed the overpass. 

The incident happened yesterday on the North Shore Line, police allege. 

The NSW Police Force has condemned the dangerous behaviour. 

"I can't understate how stupid this behaviour is," Superintendent Jason Joyce said. 

The boy was arrested at the Ryde Police Station earlier today and has since been charged with a range of offences, including two counts of entering the crew compartment of a train without permission, protruding part of a body from an open door or window of a train, throwing an time from a public vehicle or train, and throwing rocks and other objects at vehicles and vessels. 

He has been granted conditional bail. 

Officers from the Police Transport Command are in the process of identifying other young people featured in the video.