Traffic chaos after Sydney truck smash

Drivers on the M4 Motorway have endured a disastrous day of delays including a nine kilometre traffic jam.

Traffic chaos after Sydney truck smash

Traffic chaos after Sydney truck smash

Just before noon, all lanes were blocked at Merrylands after an accident involving three semi-trailers and a car left a truck driver trapped.

Suffering severe injuries, a truck driver was treated by paramedics on the M4 at Merrylands.

His legs and pelvis were crushed when his truck slammed into the back of another rig.

A doctor on his way to work was first on the scene.

It took more than 30 minutes to free the man, while the drivers of two other trucks, and a car, all walked away.

Witnesses say the blue Mercedes was clipped by one semi-trailer, another slowed, and the third slammed into the back.

The impact on the cabin was hard, the truck driver was very lucky, but the impact on the M4 was even bigger.

The jam stretched nearly 10 kilometres, all the way back to Homebush Bay Drive.