Teen daredevil risks life train surfing across Sydney Harbour Bridge

SHOCKING footage has emerged of a teen hanging precariously to the back of a train while speeding across the Sydney Harbour Bridge.

SHOCKING footage has emerged of a teen hanging precariously to the back of a train while speeding across the Sydney Harbour Bridge.

The footage, obtained by Nine News, shows an unnamed 17-year-old boy riding on the back of a Tangara as it makes its way at speed as Sydney Harbour flashes below.

With his feet on a tiny platform and just a small lock and handle to hold on to, the teen is one strong jolt away from death.

Supplied Channel 9 video stills of "train surfing" on the Sydney Harbour Bridge.

Filmed during the recent school holidays, the stunt is part of an underground movement that authorities are calling ‘urban exploring’.

Young men film themselves doing dangerous — often deadly — stunts and share them on Facebook, Twitter and other social media platforms.

It’s often a fairly elaborate setup with multiple cameras being used — on the platforms, in the train and on the offender.

Nine reporter Natalia Cooper said authorities are concerned incidents like this will become a trend and eventually lead to a fatality on the rail network.

Supplied Channel 9 video stills of "train surfing" on the Sydney Harbour Bridge.

The concern is that when scenes like this are shared among friends, one-upmanship comes into play and the risks become even greater.

“While authorities are confident it’s not yet a trend, they are concerned and they are preparing to come down hard on anyone who tries this,” Ms Cooper said.

Fines for this type of activity are in the vicinity of $200 and don’t provide a particularly strong deterrent to those taking part.

In contrast, someone who runs onto the field during an event at Stadium Australia is fined $5,500 and must front court.

Channel 9 video still of "train surfing" on the Sydney Harbour Bridge"

The incident above was one of two similar events filmed within three days of each other between the same two stations — Wynyard on one side of the harbour and Milson’s Point on the other.

Police are yet to fine anyone in relation to either incident.

More incredible footage tonight on Nine News at 6pm.