A tradie's tool triggered a big police scare on Wednesday when it was mistaken for a deadly weapon.

A 43-year-old man had been driving through the Burnley Tunnel at 4.45pm when someone called police, thinking they saw him with a sharpened blade.

Officers caught up to the driver within minutes of the call and made him pull over near the Warrigal Road exit of the Monash Freeway, police said.

He was arrested on the side of the road while police searched his car and then made the unexpected discovery.

"A screwdriver was located in his car and is believed to have been mistaken for a knife in the initial report," said police spokesman Luke Zammit.

The police operation had blocked one lane of freeway traffic and caused major peak-hour delays, but traffic was flowing again in under an hour.

The man, from Emerald, was breath-tested and returned a positive result, police said.

There's no word on charges at this time.