One man is in custody following a dramatic police chase on the Don Valley Parkway during rush hour Friday.

Toronto police spotted the man, suspected of being impaired, weaving in heavy traffic on the north-south highway.

When they tried to pull the 52-year-old driver over he veered across the road and attempted to exit at the Don Mills ramp. The vehicle slammed into a guard rail before flipping over.

No injuries were reported, but traffic was diverted in the area for a short time while police investigated.