Major road re-opened after NSW truck crash

A major road on Sydney's northern beaches has re-opened after a heavy truck overturned.

Diversions have been lifted and all northbound lanes have reopened on Pittwater Road in Dee Why following the accident which involved a truck and two cars just after 6am on Monday.

The heavy vehicle, which was carrying a container full of tiles, came down a hill and swung left before flipping on its side, witness Pat Daley said.

The truck driver escaped without injury and was taken to hospital for mandatory testing.