Three cars have been involved in a collision this afternoon, traffic sources report.
Sussex Police have been approached for comment.
The road is partially blocked following the collision which took place earlier this afternoon, traffic is said to be queuing.
AA traffic news said: "Partially blocked and queuing traffic due to accident, three cars involved on A27 Chichester By Pass Westbound from B2145 Whyke Road (Whyke Roundabout) to A286 Stockbridge Road (Stockbridge Roundabout)."
It is not known if anyone has been injured in the collision.