Mindless thugs threw a sandbag off a motorway bridge over the M62 - smashing a HGV's windscreen.
The shocking incident happened on the eastbound carriageway at Tingley on Friday night.
The filled sandbag was thrown over the Thorpe Lane bridge.
The driver suffered minor injuries from the impact but managed to move his vehicle to the hard shoulder.
Police have warned that the attack could have resulted in a fatality.