A rock thrown at a mobile speed camera vehicle near Nowra smashed the windscreen and narrowly missed the operator.
The Roads and Maritime Services’ mobile speed camera vehicle was stopped on the side of The Wool Road at Worrowing Heights, about 1.30pm on Sunday when a piece of concrete was thrown at the vehicle by a motorcyclist.
The concrete smashed through the windscreen and struck the headrest of the front passenger seat. The driver - a 65-year-old man - was shaken but uninjured.
A piece of concrete 14cm x 8cm was seized and has been taken for forensic examination.
Police have been told only that the motorcyclist was wearing coloured clothing, a dark helmet and tan gloves.
The motorcycle was being ridden east along the southern footpath at the time.
Police are urging anyone with information about these incidents to call Crime Stoppers on 1800 333 000.