A man has been taken to hospital after a truck carrying asphalt crashed and tipped over on a Melbourne freeway, sparking serious delays and disruptions.

The tip-truck collided with two cars on the busy Western Ring Road at Keilor Park about 10.40am on Tuesday, causing minor injuries to one male driver.

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Images from the scene showed the truck's rear trailer was overturned and the front of one car was smashed in.

The Ring Road was closed in both directions between Airport Drive and the Calder Freeway for more than five hours and delays built as motorists were forced to divert.

Emergency crews rushed to the scene to clear the gravel and help those involved in the crash.

The male truck driver, 54, from Thomastown, is helping police with inquiries.

Emergency crews rushed to the scene to clear debris and help those involved. Credit: VicTraffic

The exact cause of the crash is still under investigation and Victoria Police ask witnesses or drivers with dash cam footage to come forward.

Greensborough-bound lanes of the Ring Road were reopened after several hours but two Altona-bound lanes remained closed after 3pm, meaning delays stretched into peak hour.

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