STARTLING new vision has emerged of the moment a truck slammed into the Hay Street overpass on Mitchell Freeway.

The dashcam footage shows the frightening aftermath for the drivers following behind on Tuesday morning.

The impact on the bridge saw debris rain down on nearby cars, and it was lucky no one was injured.

Liam Croy was driving directly behind and estimated the truck was travelling at 80km/h when it made contact.

Camera Icon Debris flies as the truck hits the overpass. Credit: PerthNow, Martin Soo.

“A split second before the truck reached the bridge I thought, ‘he's in trouble, he's not going to clear that’,” he said.

“I'm glad that the truck squeezed under the bridge and didn't just stop dead still because I might of went straight into the back of the truck.”

Mr Croy’s car was left with two dents, while other vehicles were damaged when hit by the chunks of concrete.

After an inspection, Main Roads says the overpass is structurally sound and it will ask the truck driver, who's believed to be from Victoria, to pay for the clean up and repairs.