A pregnant woman has escaped injury after a slab of concrete was thrown at her car from an overpass on the Southern Expressway.
She was driving home with her partner just after 1am on Sunday when they were struck on the bonnet.
It happened near Honeypot Road.
It was the second incident of its kind that morning.
Another car was hit on the roof near the Majors Road overpass around 12.15am.
The State Government's considering putting CCTV up along the route and increasing rewards for people who dob in a vandal.