Along the A27 Chichester bypass from Fishbourne Roundabout, past the Stockbridge Roundabout, Whyke Roundabout, Bognor Roundabout and Portfield Roundabout, traffic is queuing with severe delays being reported.
One motorist has described the traffic as gridlocked as hundreds flock to the coast ahead of a balmy weekend.
The AA is reporting delays of about half an hour with average speeds of five mph.
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