A TEENAGER has been arrested by transit guards after he was filmed clinging to the back windscreen of a moving train on the Joondalup line.

The incident happened at around 4.30pm today, with motorists on the Mitchell Freeway filming the incident.

The teenager allegedly boarded the train at Leederville and stayed on the back of the train until Glendalough Station. He was arrested at the Stirling Station a short time later.

Trains on the Joondalup line can reach speeds of up to 90km/h.

The Public Transport Authority is investigating the incident.