A wooden fence post fell off the back of a truck and went through the windscreen of a vehicle the driver was passing.
It was inches away from hurting the driver and police are calling for information from the public saying the insecure load "almost resulted in tragic consequences".
The incident happened about 8.45am last Tuesday on State Highway 1 between Balclutha and Milton.
A vehicle travelling north towards Milton, described as a white truck with a wooden flat deck passed, another vehicle.
"The post went through his windscreen and was inches away from causing him a very serious injury," said South Otago Section Supervisor Sergeant Martin Bull.
Police asked anyone with information to call police on (03) 418 4839 or anonymously via Crimestoppers on 0800 555 111.