Ontario's police watchdog says a provincial officer is not to blame for a collision that left a 35-year-old man with several fractures last fall in Niagara region.

The Special Investigations Unit says the officer was attending to a disabled vehicle on the shoulder of the Queen Elizabeth Way near St. Catharines on Oct. 20 when the vehicle's driver ran into traffic.

The SIU says the man was struck by a transport truck carrying 18,000 kilograms of freight and was later diagnosed with fractures to his head, face, pelvis and foot.

The agency says that based on witness accounts and other evidence, it is clear the officer "did nothing to contribute to the man's rash decision, aside from being present at the time and trying to help him out."

As a result, it says there are no grounds to lay criminal charges.

The SIU is an arm's-length agency that investigates reports involving police where there has been death, serious injury or allegations of sexual assault.