SA driver falls asleep travelling at 110km/h

Startling footage has emerged of the moment a South Australian man drove his car into a guard rail at 110km/h after falling asleep behind the wheel.

The video captured by the car's dash-mounted camera shows the moment the vehicle suddenly begins drifting out of its lane on the Northern Expressway north of Adelaide.

Seconds later the car's occupants are left screaming when the vehicle ploughs into the left-hand guard rail, before slowly rolling to a stop.

The 110km/h impact cracks the windscreen and leaves smoke billowing from the bonnet.

Astonishingly no one was injured.

The video has been shared on social media to serve as a reminder of the dangers of driving while tired.