Cars stopped on Sydney motorway hit from behind by speeding truck

A truck speeding down a Sydney motorway has slammed into a row of cars the driver didn't realise were stopped in heavy traffic.

The crash on the M5 Motorway at Casula yesterday morning was captured by a dashcam of a female motorist only a few metres behind the truck carrying heavy machinery.

The footage — shared online by Dash Cam Owners Australia — suggests the truck driver had not noticed until it was too late that the traffic ahead was at a standstill.

As its brakes are slammed on, smoke billows from the tyres as the truck starts to skid sideways.

But the last-minute attempt to dodge the stopped cars fails and a long line of wreckage is left behind.

"A number of vehicles then crashed into the rear of the truck," the Dash Cam Owners Australia group wrote on Facebook.

"All motorists are believed to have suffered minor injuries."