Four cars sustained blown tyres after large rocks had been placed on Southern Expressway at Lonsdale last Friday evening.
Just after 11.30 pm on Friday, March 6, motorists travelling north on the Southern Expressway suddenly encountered large rocks placed across both lanes, near O'Sullivan Beach Road.
Four vehicles hit the rocks which caused blown tyres. Fortunately there were no injuries.
A search of the area shortly after the incident including the use of PolAir (police helicopter) failed to locate any possible suspects.
Southern District Police are investigating the incident and believe the large rocks had been intentionally placed on the roadway.
The following night two teenage boys were arrested after they allegedly damaged a car parked on the Southern Expressway.
Just before 9:00 pm on Saturday, March 7, police were patrolling the Southern Expressway area at Morphett Vale, when they saw two boys approach a Holden Commodore that was parked on the side of the expressway.
The car had been damaged the night before and was sitting in the emergency lane with a flat tyre. The two boys approached the Commodore and started throwing rocks at the car windows. The nearby patrols quickly converged on the area and arrested the two boys.
Both 15-year-old boys from Morphett Vale were charged with property damage and illegal interference with a motor vehicle. Both boys have been remanded in custody and will appear in the Adelaide Youth Court on Tuesday.
Police investigations are continuing following the incident the previous night after large rocks were placed on the northern carriageway of the Southern Expressway.
Anyone with information on the incidents are asked to contact Crime Stoppers on 1800 333 000.
It is not known if the two incidents are linked.