Spy cameras will be trained on motorway footbridges outside Leeds after the latest in a series of incidents of missiles being thrown at cars.
Police said a motorist narrowly avoided being hit after a rock was dropped onto the M621 on Thursday night.
It was the sixth reported incident in as many weeks.
Highways Agency CCTV cameras will now be directed specifically at the walk-ways during off-peak periods. Officers will also be carrying out extra patrols in the area in a bid to deter yobs.
Sgt Sam Greaves, of Holbeck Neighbourhood Policing Team (NPT), said: “There have been a number of incidents over the last couple of weeks where items including bricks and bottles have been thrown from motorway bridges across the south Leeds area. There have been a number of vehicles damaged but so far no-one has been seriously injured. But it could only be a matter of time.”
As reported in the YEP last week, a 25-year-old man was lucky to avoid serious injury after a rock smashed through the window of his car as he drove on the M621 on October 12. He suffered only slight injuries to his chest and managed to bring the car to a safe stop.
That followed other incidents, including one in which a woman and her daughter escaped unharmed when a brick was thrown through the windscreen of their car.
Thursday’s incident happened when an object was thrown from one of the bridges between junctions four and seven, but missed its intended target.
“I can’t emphasise enough how dangerous this is,” Sgt Greaves added.
“It’s happening worryingly often and it needs to stop before someone is badly injured or worse.”
People can report anyone acting suspiciously via 101.