A collision between a semi-trailer and a 4WD caused traffic chaos on the F3 yesterday.

Shortly after 1pm the 4WD that was towing a caravan collided with a B-double semi trailer near the Doyalson turnoff.

The caravan was completely crushed in the crash, its contents strewn across the side of the freeway.

Local area commander Chief Inspector Tony Long of Tuggerah Lakes Police said witnesses are being interviewed to determine the cause of the crash.

The incident caused traffic delays with the northbound lanes of the freeway partially closed for up to two hours.

Witnesses said the 64-year-old truck driver was visibly shaken by the incident.

Anyone with information relating to the crash is asked to call Tuggerah Lakes Police Station on 02 4333 2999.

Pictures: Phil Hearne