Traffic on the A30 between Camborne and Redruth has come to a standstill during rush hour on Wednesday.
The congestion built up on the eastbound side of the dual carriageway near the junction for Pool at Tolvaddon.
The delays have been caused at first by a broken down vehicle, which was partially blocking one of the lanes.
Police were called to the scene and one lane of the A30 was closed. Witnesses stuck in traffic said the road the congestion was so bad that queuing traffic came to a stop at times.
Then shortly before 8.30am, four cars collided at the entrance to lane closure area for the broken down car. This extra incident has created even more problems.
Updates on this incident will appear below.
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